Common Nitro RC Car and Truck Terms
If you're new to the world of nitro RC car and truck racing there are a few basic terms that you will hear over and over. If you want to go on the track and look like you've been racing for years instead of some green newbie, learn these terms and learn to talk the talk!
first term you'll need to know the full meaning of is "nitro". It refers to any fuel powered vehicle or the fuel itself which is gas mixed with the fuel additive nitromethane. The mixture of the nitro can be anywhere from 10% to 40% added to the gasoline, but normally is in the 20% range.
Another common term you'll hear a lot is "glow engine". This is the engine of your nitro RC car or truck. The engines have a glow plug (definition coming) and they work in the same fashion as a spark plug. The filament inside the plug glows when it gets hot.
Which brings us to the next common RC car and truck term "glow plug". The glow plug heats the fuel mixture in your nitro RC car or truck and when it gets hot it begins to glow. The glow plug is heated with a battery powered glow started or glow plug warmer. Once the engine is running however, good old fashioned combustion takes over to keep the engine of your RC car or truck running.
The fourth definition you need to know is "glow starter". This is a battery powered device that you can attach to your RC car's glow plug to heat it up to get your vehicle going. If you are running your RC car or truck outside in colder weather, this is a very handy gadget to have around.
Now that you know the basics of the RC car and truck lingo. You can get out on the track not sound quite so new to the fun sport of RC car and truck racing!
RC Nitro Car Basics
Now that you know the basic nitro RC car terms, you should also know the very basics about your RC car or truck itself.
You will need to prep your RC car or truck before a race. Prepping a nitro RC vehicle isn't too far away from the necessary preparations you need to make to race an electric RC car. However there are a few extras that need to be done:
Check your engine fuel settings. If this is your first race, even if your Nitro RC car said RTR (ready to run) the engine will probably still require a little breaking in. Read your manufacturer's manual to get the proper fuel settings and until you know your RC car, use those settings as the safe middle ground for running your RC vehicle. Generally, breaking in an RC nitro engine involves running your car through roughly 3 to 5 full tanks of fuel and while not hitting top speeds, using various different speeds to make sure all the gears are working. Don't overheat your RC car during break-in and take a break between runs.
When you're done running your RC car for the day. drain the fuel tank or you run the risk of contamination to your fuel through condensation. Also make it a point to clean and oil your air filter. Adding the after-run oil to keep your RC vehicle lubricated so it will be ready to roll for the next race.
And those are just some of the basics for owning a Nitro RC car or truck. Use these tips to keep your RC vehicle running in tip top shape!
Clutch Tuning Getting Power to the Ground
by Ed Bridges
Every nitro RC vehicle has some sort of clutch that engages and disengages to provide power to a transmission or differential. Having this clutch working properly can mean the difference between a strong bottom end and a soft bottom end. When the clutch is engaging too early, it causes a low-end bog. The first thing most people do when this happens is to lean out the fuel/air mixture. If done to the extreme, this can shorten the lifespan of any nitro engine, as it is allowing more air and less fuel to enter the engine. The engine will run excessively hot and won't have enough oil to maintain the lubrication. I see newcomers, and even some experienced tuners, making this common mistake. If you're constantly trying to tune the engine to get bottom end, there's a good chance the clutch isn't working properly. If your nitro truck or car doesn't seem to have the bottom end it once had, or if you just want more low end power, follow the steps below to tune your clutch for maximum grunt and to get you off the line before the next guy.
If your engine is tuned correctly, the clutch shoes shouldn't be engaging while idling. When removing the clutch bell, pay close attention to the order in which any shims or washers were installed so that it can be reassembled the same way.
The car idle. If it begins to move forward then your clutch is engaging too early. Check the engagement time by slowly increasing the engine rpm from idle and noticing when the car starts to move forward. I like to get 1/8 throttle before the clutch shoes engage. This will vary, depending on servo and radio setup. In general, you want to be able to idle up enough that the engine has a noticeable rpm increase. If the car moves the instant you begin to increase throttle then it's engaging early. This can be beneficial on loose tracks where having too much bottom end will cause the wheels to break free when accelerating. However, most of us weekend racers and backyard bashers want axle-breaking bottom end power. Remove the engine from the car and remove the clutch bell. Pay close attention to how the clutch comes apart: how
As the flywheel spins, the clutch shoes are forced outward to engage the clutch belt.many shims are used and where they go. There are several types of clutch systems out there. Most common on small blocks is the 2-shoe design. And the most popular for trucks and buggies seems to be a 3-shoe setup. No matter what setup you run they all work the same way centrifugal force. Remember the Gravitron at the fair? The thing that looked like a big UFO? You went inside and stood against the wall, and when it started to spin the walls rose off the ground, taking you up with them. Then, as it was spinning, you could climb around the walls like Spiderman. Well, it was centrifugal force that kept you against the wall. Did you happen to notice that as it sped up some people could lift their feet sooner than others? That represents how weight affects centrifugal force. It's the same with our flywheels: The faster the flywheel spins, the more centrifugal force that's applied to the clutch shoes. It forces them out to make contact with the clutch bell. The weight of the clutch shoes and the spring tension determine when they engage and disengage.CLUTCH SHOES
A light clutch shoe will allow the clutch to engage at a higher rpm. A heavier shoe will engage earlier. You can lighten the clutch shoes by doing one of two things. You can drill holes in the side of the shoes, but do this in the same spot on each shoe. Start small, and drill another hole if needed. Or you can drill out the first hole bigger, or a combination of both. The second option is to trim the shoes on the trailing edge. Do this with a fresh blade on your hobby knife. This will give you a smooth and easy cut. Try to remove equal amounts on all the shoes.
Removing weight from clutch shoes will allow them to engage at a higher RRPM. You can do this either by drilling a whole in each shoe or by sutting material from the trailing end with a sharp hobby knife.CLUTCH SPRINGS
For 3- and 4-shoe clutch systems, the springs are rated from soft to hard: .9, 1.0 or even 1.1. Some just say soft, medium, or hard. On single spring clutches, the length of the spring affects the tension. A short spring will have more tension to hold the shoes back. A thicker or heavier spring will do the same. Both types will make the clutch engage at a higher rpm, similar to running a light clutch shoe. A stiff spring will also allow the clutch to disengage faster when letting off the throttle. This will let you roll through the turns without the engine wanting to pull you.
Clutch springs, including the types shown here, will wear out over time and have the potential to break. Periodic replacement is necessary.I personally like to run 1.1 springs with stock shoes on my 3- shoe flywheel and then drill the shoes for fine tuning. Just remember that the springs do wear out and lose their tension and the shoes will become glazed, which could cause slippage. I like to change my springs every two gallons of fuel and check and replace the shoes as needed. You can remove the glaze from the shoes by lightly going over them with fine sandpaper. If your clutch bell is glazed inside with clutch shoe material, you can remove that the same way. Finding the right combination of clutch shoes and clutch springs can be time consuming, but in the end, it's well worth the effort.
Experiment with different clutch shoes and spring combinations to find the Clutch shoes will accumulate a buildup over time. You can renew the surface with fine sandpaper. The same is true for the inside of the clutch belt. combo that best suits your driving style. Before you know it, you'll be able to buy new shoes and know exactly where to cut or drill for the performance you want. I stick with one type of spring and tune the shoes according to different track conditions.
CHOOSING A CLUTCH BELL
You can also get better acceleration by changing the clutch bell. If you are running a 14-tooth bell, you can drop to a 13 for better acceleration, but you will lose top end speed. If you're looking for more top end speed, you can increase the clutch bell size to a 15-tooth. This will give you more top end speed; however, bottom end acceleration will suffer. Something to keep in mind is the inside diameter of the clutch bell affects when the clutch engages. OFNA clutch bells have a larger inside diameter than most on the market, and they will let the clutch engage later if used on a smaller flywheel design. No matter what size clutch bell you use, the clutch shoes and springs have to be working properly to get Switching to a larger clutch bell like the one on the left will improve top end and hinder acceleration slightly. A smaller clutch bell, shown on the right, will improve low end and hinder a top end. the clutch to work right.
After the springs and shoes have been mounted to the flywheel, it's time to reinstall your clutch bell. Reinstall it in reverse order. Did you remember where the shims went? If you are using a different bell then you may have to shim more. With the clutch bell on and tight it should spin freely. If it doesn't then it needs to be shimmed so you have minimal endplay. Endplay refers to how much the clutch bell will slide back and forth on the crank. A little play is all right, but too much will cause your clutch bell bearings to fail early. OFNA makes a clutch shim kit that has every shim you could ever use. After you get it shimmed, reinstall the engine and go rip up some dirt, grass or asphalt.
One of the most popular subjects in RC is speed. Experienced hobbyists love to point how the only two questions the uninitiated have when they see an RC running are: how fast and how much? Going fast isn't just on the mind of newbs. Truth be told, we're all interested in going faster. Racers quickly point out that it's not how fast your car is that matters, what matters is how fast you get around the track. I know I'm guilty as charged, but if racers actually believed what they say, they wouldn't be buying latest motors, speed controls and batteries every time something hot hit the shelves. Bashers, in contrast, readily admit they have a need for speed. The bottom line is that we're all a little obsessed with speed, and more specifically, going faster. Check out these five top ways for going for faster with your electric ride.
Changing to a larger pinion will make your car faster. Most people learn that pretty quick and odds are you already knew that. A larger pinion will also make your electronics run hotter specifically your motor and speed control. You'll also lose run time and acceleration. Pinions aren't the only gears that can be changed on most RC cars. It's often easy to swap out a spur gear. You'll need to go smaller for more speed and it's worth noting that the results will be far less noticeable per tooth count change. You can probably expect to gain 2mph from a single tooth pinion increase in most applications.
Increase Motor Timing
Increasing motor timing will increase rpm which in turn will result in more speed. Timing increases on brushless motors tend to yield more subtle results compared to brushed motors, but you will see positive results in both cases. You'll have to watch your motor temperature and make sure it stays below 160 degrees F.
Changing tire size is like changing gearing. Taller tires cover more ground per revolution, so your car will be faster at the same motor rpm as it was with shorter tires. Off-road, the results will subtle unless you go to a really huge tire. When racing on-road, specifically with foam tires, this is an important part of race tuning. A half inch increase (pretty significant) tire diameter will yield approximately an increase of about 4 or 5mph.
Higher Kv or Lower Turn Motor
This is the old fashion way to get more speed add horsepower. Most brushless motors have Kv rating and the higher the Kv rating, the more rpm a motor will put out per volt. If the Kv rating isn't listed, a turn rating will often be used. With brushed and brushless motors, a lower turn rating equals more rpm. Always check the limits of your speed control before installing a "hotter" motor. Increasing your motor's Kv rating 2,200Kv can yield an increase of 20mph if your are using the same brand and model motor and have batteries that can supply the needed juice.
If you're only going 25mph, aerodynamics aren't going to play too noticeable of a role. If you're going 50mph, aerodynamics will certainly start becoming influential on top speed. In addition to mounting a low profile, sleek body shell, mount it as low as possible and keep the wheel wells as small as possible. Open up the rear of the body to let trapped air to escape.
Higher Voltage Battery
Want to see some serious speed gains? Go from a 2S (2-cell) LiPo to a 3S (3-cell) LiPo. This jump from 7.4 volts to 11.1 volts can increase speed by as much as 25mph! Make sure your speed control can handle the extra voltage or the only thing you'll be fast is going to the hobby shop for a new speed control. You'll also want to make sure your chassis can accommodate the the larger pack.
Better Grip Tires
All the extra power won't do you much good if you can put the power to the ground and put it to use. Invest in some high-quality aftermarket tires in a soft compound and you'll be going faster. by Matthew Higgins ( Taken from RC Car action)
How Do You Know If Your Fuel is Bad?
If you picked up your fuel jug to go fill your RC car and noticed droplets of water inside, stop. Those droplets of water inside a fuel jug will contaminate the fuel. It is best to safely dispose of that fuel and invest in an airtight fuel jug and there are other ways to fight the moisture problem.One of the first ways you can tell you are using fuel that has been water contaminated is your car will have degraded performance or may not start at all.
Your RC cars fuel is made up mainly of methanol (alcohol). Methanol is hygroscopic meaning that it attracts moisture. This can cause your fuel to be contaminated with water, which will cause poor engine performance. Additionally, the UV (ultraviolet) rays in sunlight will eventually break down the nitro-methane if the fuel jug is stored in sunlight for long periods of time.
Use a metal can first off out in the field. When you store your fuel at home, squeeze all the air out of the fuel container and an even better idea is to store your fuel in smaller containers that you have removed as much air as you can before sealing. When you're racing your RC car outside, especially in warmer weather, you can all but expect condensation to happen in your fuel bottle. When you're racing, just bring the fuel you'll need for the day and leave the rest safely stored at home, this will keep your fuel supply uncontaminated by moisture and always ready to run.
About Your Nitro RC Car Fuel
If you're an RC car enthusiast, you probably have read a lot of magazine articles and websites regarding car fuels.
The main argue points among most people is what type of oil is needed for car fuel and how much should be used? First of all, skip the advice you got on using airplane fuel. Car engines work completely different from airplane engines. The workings are different and airplane fuel can be up to 20% oil, an RC car typically needs only 8-12%.
If you use fuel with a higher oil content, contrary to popular belief, it will not improve your engine life. Too much oil will actually degrade the performance of your car's engine and in some cases can lead to overheating of the engine. Keep your RC car engine running crisp at roughly 8% but no more than 12% added oil to your fuel.
The story that airplane fuel will run in your RC car better and give your engine better protection, is just that: a story. Use the fuel made for your RC car's engine and you will get a much longer life out of your RC car without the fear of damaging the internal workings of your car's engine.
Also, keep your RC car fuel tightly sealed and away from moisture as water will seriously degrade your car's fuel. If you have old fuel in your garage, toss it safely and invest in fresh fuel for your RC car, your engine is worth it!
Do you Know How to Carpet Race?
If you love to race you RC car and you live in a place where winter makes outdoor track racing impossible, you might enjoy carpet racing.
Indoor carpet racing is a great way to still be able to race your RC car or truck and not have it exposed to the elements. Mostly popular in the mid-west part of the country during the winter months, carpet racing is also gaining popularity in places where the winters are mild but the summers are blazing as an escape from the extreme heat.
Driving on carpet tracks requires different techniques for controlling your RC car as opposed to pavement or standard track racing. When you begin carpet racing with your RC car, first of all - get in all the practice you can. Do several practice laps and learn where you need to begin turning your car at each corner to avoid crashing or rolling. Your RC car will maintain a pretty good grip on the carpet track so you can push the limit and make sharper turns on a carpet track than you can on a pavement track.
Start off a little slow and then go a little faster with each successive lap. Make a note in your mind where each turning point is and then you can go out on the track and look like you've been carpet racing for years.
Use the creep method for taking on corners. Maintaining your speed around corners is easy if you let off your throttle slightly and then the resulting slight braking action will cause a weight shift to the front of the car. This lets the RC car hug the track when going around a corner and with practice you will be able to take corners faster than ever before.
When carpet racing your RC car, the inside line is prime position. Most carpet races have stagger starts that greatly reduces the chances of the first lap pile ups that you have no doubt experienced. Most of those pile ups happen on the outside lines, go for the inside and you can normally escape the damage if someone else causes a pile up.
Carpet racing is a blast with your RC car, ask your local hobby shop if there's a carpet racing track near you!
Shorter camber links, more camber gain. Lower roll center, allows car to transfer more weight side to side, raise upper camber link on tower. Less anti squat. Allows more weight transfer to the rear for more traction on power. Lighter diff fluids, allows tires to move more independently and hopefully pick up traction.
High Bite Tracks
Longer camber links. Less camber gain, chassis more flat. Higher roll center, allow less chassis roll, lower upper camber link on tower. Move shocks out on the arm, stabilizes and mellows out the car. Heavier diff fluids, won't diff out as easy, could be faster though corners and on acceleration. Stiffer springs, less chassis movement.
Track with Big Jumps Flat Landings
More pack, use smaller hole pistons or less holes to get desired pack so car doesn't bottom out so bad. Thicker shock oils to get to pack up more. Shocks out on the arms, stiffens shocks and less leverage from outside of arm.
Very Rough Track
Less Pack. Use bigger hole pistons or more holes, must make sure why car is bouncing, is it due to packing up or is it due to bottoming out. If due to packing up, use less pack, if bottoming out then perhaps need a little more pack. Lighter center diff fluid, helps to give up energy when hitting bumps and makes car more front wheel drive. Less toe while this may make the car looser it can help go through bumps in the corners without catching as bad. More droop. This is dependent on type of ruts but generally more droop can help absorb the ruts better.
Quicker shock rebound, perhaps using stiffer springs or a tapered piston to allow quicker rebound may help. On a rough track it is hard to say exactly which type of shock package will work. There are two basic ways you can go. You can go with smaller pistons with lighter oil and stiffer springs so you have really quick rebound to try to work through all the bumps. Or you can go with bigger hole pistons with thicker oil and softer springs to try to make the car soak up all the rough. You'll have to try both to see which works best.
The History of IFMAR
by Ted Longshaw
No History of IFMAR would be complete without a brief reference to what actually led to the calling of the meeting in Geneva, where it was agreed that a World R/C Association should be formed.
Ted Longshaw took part in the first l/8th scale R/C car meeting to be held in England on Easter Monday 1971 and thereafter was involved with the formation of the BRCA in the U.K., along the way getting very enthusiastic about this exciting new hobby. This led to him taking part the next year in the ROAR Open National Championship at the Briggs Cunningham Museum in California.
Subsequently competing in the same Championships in '74 and '75, he tried to persuade some of the U.S. racers to come over to Europe, without success. He therefore suggested that he try to get some Europeans together to come and race in California in 1977, if such a race could be arranged. John Thorpe agreed that ROAR could use his raceway and Ted set about organizing the trip, through his position as President of EFRA.
The first so called 1/8th World Championship therefore took place as arranged but, in truth, apart from the 20+ Europeans, the rest of the world was represented by ex-pats living in the U.S. It was suggested and agreed by everyone there that the next W.C. should be in Europe in 1979 and it was left to EFRA to arrange everything.
Meanwhile, Monaco wanted to hold a W.C. in 1978. As it had been agreed at the Thorpe Raceway that the next W.C. would be held in 1979, Monaco compromised with EFRA and agreed to hold a so-called World Cup. Several ROAR members came over and took part and went back to the U.S. with memories, not of the racing, but more of the liberated views of European women whilst sunning themselves at the poolside next to the track. (The pool you all have seen on the T.V. during the full-size Monaco G.P.). Cameras normally used to capture pictures of the latest modifications to cars, were all suddenly fitted with telephoto lens and pointed in a different direction.
EFRA, meanwhile, decided that the application from the Geneva club in Switzerland to host the World Championship had the most merit and it was decided to hold the race there. Splendid pictures exist of the final of this event and, even now, there is no doubt that there were more spectators there than at any other R/C car race before or since!
Ted Longshaw called a meeting of all interested persons on the Monday morning immediately following the race with the idea of creating a world-controlling body that would not only establish uniform construction rules but would also ensure that there was only one World Championship that counted. (There were numerous clubs and organizations starting to advertise that their next race was to be a W.C. and, had this been allowed to continue, the whole prestige of a World Champion title would have been completely devalued.)
At the meeting, which was attended by many well-known names, such as Gene Husting (Associated), Ken McDowell (Parma), Keith Plested (PB Racing), Pieter Bervoets (Serpent), etc. - around 30 people in all, it was agreed that such an organization should be set up. South Africa's Wennie Bester suggested the name International Federation of Model Auto Racing and it was agreed. (It was a compromise to leave out any reference to R/C, as at that time, there was a possibility that the existing round the pole cable racers might want to join.)
It was agreed that W.C.'s should be held every two years and rotate alternately between the three blocs, i.e. it only came to your bloc once every six years. As there was effectively only one class then, it was thought that this would allow enthusiasts worldwide to meet every two years. I don't think that even the most optimistic manufacturer there thought that one day it would be as big as it is now and involve the worldwide travelling that is now necessary.
Ted Lonsgshaw was proposed as President/Secretary by Gene Husting and IFMAR was born and on its way.
To aid administration, it was suggested that it was made up of three equal voting parts, roughly speaking, Europeans, Americans and the Far East. Each would administer its own area and for W.C.'s would receive an equal allocation of 40 places. (There was only one class racing then, i.e. 1/8th I.C. circuit.)
Getting the Far East part of the equation to work proved quite a task and the original setting up of FEMCA is another full story in itself. Suffice it to say that it now works very well, with eleven member countries, all under the guidance of John and Marian Grant who really are quite indispensable.
Originally, the only time everyone actually got together to hold a meeting was at the 1/8th W.C. Everyone was kept informed of what was going on by a regular monthly newsleltter sent out by the President/Secretary/Treasurer who, at that time, was a one-man committee.
WHAT HAPPENED ALONG THE WAY FROM INAUGURATION IN 1979 UNTIL 1996.
1/8th World Championship in Geneva, (strictly speaking not yet really an IFMAR event, for IFMAR was not yet born), was won by Phil Booth from England driving a PB Racing car. Phil is now Development/Design Engineer with Schumacher and is responsible for many of the new ideas seen on these cars. He still retains his driving skills and recently was part of the Schumacher team taking part in the annual PARIS 24 hour race.
First attempt at forming FEMCA in Hong Kong. Monaco "World Cup" won by Phil Greeno from England, also driving a PB.
A 1/8th I.C. IFMAR World Championship was held in Indianapolis which was won by probably the only driver from the original 1977 race still capable to-day of making the A main at a World Championship, Arturo Carbonell. Art is now part of the Serpent organization in the U.S.A.
First 1/l2th W. C. It had been decided to run this electric race in alternate years to the 1/8th I.C. Associated Electrics won and started their domination of Electric R/C racing W.C. titles.
The 1/8th Circuit W.C., back in EFRA this year, was held at the Carnoux track, a superb purpose-built facility, now, unfortunately, no more. The race remains memorable now, more for the disputed result, (there was no electronic timing in those days) and the resultant Court case, than for the superb presentation of the whole event, which is a pity. IFMAR though learned something, especially the President, who ended up being sued in the French courts for approximately 250,000 pounds damages. This lesson resulted in the first version of the World Championship Contract, now refined several times, between the promoter and IFMAR.
This dispute also has another interesting story in that it reinforced the determination of a young University scholar in Holland to perfect a way of automatically timing and counting the laps on R/C cars. He used the project as part of his studies to obtain his degree in Electronics. He is now responsible for the timing equipment used at almost every major motorized race you see on T.V. There may be advertisements showing various clock and watchmakers, but the signals that feed their equipment all come from the same source that originally started out trying to stop arguments at R/C car races about how many laps each car had achieved. This most successful of businessmen is Pieter Bervoets' brother, Fons.
The first 1/10th Off-road W.C. Electric racing was now getting very big in the U.S.A. and this first event was held at the very heart of the most active area in the world at that time, Del-Mar, California. Associated Electrics were instrumental in helping this along and one began to hear more and more a name that is now a legend in R/C car racing and motor building in particular, Mike Reedy. Mike was asked to head up the Electric Section of IFMAR and served as Vice-President until last year. He played a big part in forming the rules that now govern all Electric racing, whatever scale, and is still part of the ROAR Executive.
FEMCA, at the third attempt, was now up and running successfully and hosted its first W.C. event, the 1/8th track event in Tokyo. Mike Reedy, in his position as Vice-President of IFMAR, acted as Race Director and says he lost count of the number of approval dockets he signed during the race. Suffice it to say that it was a well-run race enjoyed by everyone who was lucky to be there.
World Championships continued, alternating each year. Bi-Annual General Meetings came and went, more countries joined. At the 1987 1/8th Race in Holland, EFRA pushed for a fourth non-voting to be formed, comprising countries outside the geographical areas of the existing blocs. In 1986, the first 1/8th I.C. Off-road W.C. was held in France and in 1992, at Ranch Pit Shop, California, the first 1/10th Electric Circuit W.C. was organized. There are now five different IFMAR W.C.'s (soon to be six with 1/10th I.C.) and Ted's original ideas, some of them incorporated in the first paragraphs of the Constitution, have been realized. The first clause, even today, is that IFMAR exists to promote international friendship. The other prime reason stated at the formation that there should only ever be one recognized World Champion of any particular class, has also been achieved. Without IFMAR, R/C car racing could have ended up like boxing with a myriad of titles, none of them recognized by everyone. As it is today, an IFMAR World Championship is truly just that. In 1995, at the Bi-AGM held at the 1/8th W.C. in Phuket, Thailand, Ted stepped down, was appointed Hon. Life President and handed over to the new President, John Grant and Marian Grant was appointed Secretary/Treasurer.
IFMAR today is a professional organization, using volunteers who give their time but do receive something towards their expenses. It has its own legal advisor and the Hon. Life President is also available, if needed, at any time. A total of 42 countries worldwide are members through their various blocs.
Ted Longshaw at the 2010 Offroad World Championships in Pattaya, Thailand, with the Track Coordinator
Ten Tips to Get That Engine Running
Mar 11, 2011No Commentsby Kevin Hetmanski
Nitro engines aren't a plug and play deal like brushless power and because of that, time needs to be spent tuning and trouble shooting them in order to enjoy your time with them. These engines are very simple machines and don't require much to run. If it's getting air, fuel and spark, the engine will fire. But things don't always go smoothly and there will be times where you have to figure out what the engine is asking for in order for it to run correctly. These 10 tips are here to help you end the frustration and start up the enjoyment.
Engine won't start
Check to make sure that your glow starter is fully charged. You can quickly check by taking a new glow plug and plugging it into the end of the starter. If it glows, then it's charged and the problem is somewhere else. If it doesn't glow, then need to charge it or replace the battery and you should be good to go. If the glow starter isn't your problem then you might have a bad glow plug. Remove the glow plug from the engine and test it by plugging it into the glow starter. If all else fails, check to make sure you have fuel in the tank. Yes, that's something that people over look.
Engine starts but stalls right away
OK, so you fire up your engine and it's running fine then the second you pull the glow starter off the heat sink head, the engine dies. This could be a sign of a glow starter that isn't fully charged or a glow plug that is one the edge of going bad. Start by putting your glow starter on charge or replacing the battery and try it again. If the problem still happens, replace your glow plug.
Engine runs on starter box but stops when vehicle hits the ground or when you tap the brake
This is happening because there is something hanging up on the clutch and not allowing it to disengage from the drivetrain. So the second you stop the drivetrain in any way, the engine will die. The same thing happens when you hit the flywheel to shut the engine down. Remove the engine from the chassis and spin the clutch bell to see if there's any drag or if it's locked all together. If there's drag on the clutch bell, then you may have a clutch shoe or clutch spring hanging up. If the clutch bell is locked up all together, you have a bad clutch bell bearing. Replace both bearings even if only one clutch bearing is bad because chances are that the other one is on the same path.
Engine stalls when you hit the throttle
This is a sign that your high-speed needle is set to lean and the engine is starving for fuel. Simply richen the high speed needle a quarter turn and make fine adjustments from there to get it set properly.
Engine looses power when you hit full throttle
This is a sign that your high-speed needle is set too rich. A sign is that the vehicle isn't as fast as it was when the engine had a proper tune and you'll see lots of smoke coming out of the pipe. Lean the high speed needle until your engine is running properly and at the correct temperature.
Engine struggles to move vehicle
Two things can be going on here. Your low-speed needle is set to rich or two lean. If you get on the throttle and your engine wants to die the second you touch it, your low speed needle is set to lean. If your engine is slow to react and stalls, then your low-speed needle is too rich. To check the condition of the tune on the low-speed needle, I like to do the pinch test. Drive the vehicle around if possible to clear it out and bring it over to you and immediately pinch the fuel line. You want the engine to run for a second or two before stalling out. If the engine dies right away, the low-speed is set to lean. If it takes longer, then your low-speed is set too rich. If you can't get the vehicle to run enough to clear the carburetor out, perform the pinch test to get a general idea of where you're at.
Engine runs too hot
An overheating engine can be caused by lack of air flow or a carb that is set to lean. Take a look at the body on your vehicle and make sure that there are venting holes in the windshield and behind the cab. Richen up the high-speed needle on the carb. A dirty engine can reduce the cooling capabilities of the engine and cause it to overheat. A tooth brush and some nitro cleaner will do a great job at removing any grime.
Fuel not reaching engine
If you are trying to fire up your engine and you see that the fuel isn't flowing to the carburetor, you have a clog in the fuel system. You can check the fuel tank by removing the pressure and fuel line from the pipe and engine. Once they are removed, you can blow into the pressure line and look to see if any fuel comes out the other. The fuel should flow with no effort. If it takes a lot of pressure to make the fuel come out or it doesn't come out at all, the fuel tank is clogged and needs to be replaced.
Engine runs erratically at idle
It can be frustrating when you can get the engine to idle consistently and that's because of an air leak in the engine or fuel tank. Check the tank for leaks by plugging the exhaust and fuel lines and submerging it in water. While under water, check for air bubbles. Another area where you can find an air leak is in the fuel lines. If you see bubbles flowing inside the fuel line or suspect that is where your air leak is coming from, replace the line. It's not expensive and needs to be done from time to time anyway. You can also take the engine apart and seal the back plate, carb, and high-speed needle assembly with O2 safe sealant.
Engine won't turn over
Two things can keep an engine from turning over, too much fuel in the combustion chamber or a seized piston and or crankshaft. If your engine was turning over the suddenly locks up, chances are that you have a hydra lock condition where there's too much fuel in the combustion chamber. All you have to do to fix it is remove the glow plug and turn the engine over to blow out the excess fuel. If that's not the problem, then you'll be replacing parts or an entire engine if you have a seized condition.
What is the ideal engine temperature?There are a lot of theories out there on what the best operating temperature for your engine. Some look for an engine temp of 230 some may recommend a higher temp. Before running any nitro engine, take a look at the owner's manual to see if there's a recommendation there. Ever engine is different and a temp that will work for one engine might not be ideal for another.
How to Read your Rc Glow Plug.
Do you have your Nitro Engine Tuned Correctly?
What exactly is our glow plug telling us.So you are wondering if you have rc nitro engine tuned correctly.You check your temperature on a regular basis, but you are still not sure.You can examine your glow plug to get a very good idea. Examining the glow plug is a peek inside the combustion chamber.But let's get the big picture and take the head button off, while leaving the glow plug installed in the head.What we are going to see by looking at the head button and the glow plug is the entire combustion process.This is going to show use just what is left after the burn process.By looking at the entire combustion chamber we can analyze what was happening during the burn.Let us explore a few different tuning examples below.
Pictured above is an example of a Rich Setting.
This is what your glow plug and head would look like after break-in.
The head and glow plug will be very wet with oil. Every thing still looks new.
No discoloring of the head, plug body or plug coil. If this is the look just after break-in that is great.
But, if this is post break-in then you are going to need to start leaning the engine out, to reach correct combustion.
If you run in a too rich state for a long period of time, oil will build up in the crank case and cause the front bearing seal to leak.
Running too Lean:
The previous example is of a Too Lean or Detonation Condition.
Upon examining your head and glow plug you find or feel little or no oil residue.
The glow plug body is blued. The coil wire has broken away from the plug body.
You see that the combustion chamber is silver to slightly tan. Plus the head and glow plug are extremely pitted.
Your nitro engine is running too lean.
The pitting is caused by detonation.
Detonation is when the fuel air mixture pre-ignites in many different areas of the combustion chamber at one time.
The top of the piston will show the same kind of damage. If you see this kind damage you need to richen up your engine.
You may need to also shim your head. Increasing your head clearance will lower compression and lessen the possibility of detonation.
Running Borderline Lean:
In the above example you can see why it is important to look at the head and glow plug together.
This example shows a Borderline Lean with a Good Glow Plug.
By just looking at the glow plug you would think that your nitro engine tuning was correct.But, looking at the head you see that there is some pitting occurring.
With seeing this damage you know that your rc nitro engine is tuned too lean and you need richen your carberator setting some.
If you are a serious racer, this is how your glow plug and head should look.
Above is an example of a Perfectly Tuned Race Engine.
As you can see on this head and glow plug there is an even coloring across the combustion chamber and glow plug.
If you do a lot of racing this is the coloring you are looking for, that light brown to deep golden color.
This shows you that you are getting the most out of your engine. Your nitro engine tuning is producing maximum power and you have the perfect tune on your engine.
The only thing that you will need to do is keep your eye on is atmospheric conditions, temperature and humidity.
As these conditions change, so is the tune on your engine. So, always be aware of the weather conditions to help with your nitro engine tuning.
Running it safe:
The previous example is of a nitro engine that has a Safe Every Day Tune.
If your head and glow plug look likes this example and you are a novice racer or a basher, this is great.
You have done a great job of tuning your nitro engine.
The combustion chamber shows a little color, gold to tan.
Plus, the chamber and plug are still quite wet with oil residue.
The glow plug also shows some color on the body of the plug, grey to tan.
The coil wire will be shiny, silver and still have a new look to it.
The only place the coil wire should show some color is where it contacts the outer body of the plug.
At this point the coil wire should be slightly black.
This head and glow plug show an engine that is running great, a little on the rich side.
This type of tune on your nitro engine is very good to get the maximium life out of your engine.
Plus, this tune would be great for bashing and even for most of us weekend racers.
Taking the Mystery out of the Glow Plug
In this example we see a glow plug that has been run at a Lean Setting and has got very Hot.
On inspection we see that the outer body has turned black.
The coil wire has a white dusty appearance.
Plus, the coil wire has small breaks in the electrode wire.
All of this is due to the very extreme heat of running lean.
This glow plug is near failure, the coil wire is close to breaking free of the body.
If the tip of the coil wire was to break off it could travel down into the engine causing severe damage to piston, bearings and head button.
But, most times when the coil wire does break off it will just go out an exhaust port causing no damage.
This will not always happen, if the coils wire stays inside the engine it will destory many internal components.
I hope this has given you a little insight about nitro engine tuning. The glow plug what makes our nitro engines run.
Besides just looking at our glow plugs, it is important to remove the head button and look inside our engines on a regular basis.
Doing so is going to give us the whole picture of what is going on, not just a little peek the glow plug gives.
Yes, checking our glow plugs often is very important and gives a good look at what is going on inside our engines.
But, just remember that this is not the big picture.
Take a few minutes to clean your engine thoroughly, remove the head button and take a close look at what is going on inside.
The "right" glow plug for your engine is the one that gives you the best performance. And you can choose the right plug for any situation, just by following the guidelines below.
1. Engine Type - Know what type of engine you have. Is it a standard - or a turbo?
Standard engines (engines with a 1-piece head) are most common. Standard plugs are easily available, inexpensive and fit almost all standard engines. Standard plugs are installed with a washer, which creates a compression seal with the head.
Many new engines are turbo engines, which feature a special 2-piece turbo head. The biggest benefit of turbo plugs is superior performance. Unlike standard plugs, turbo plugs (identified by a "P" in the description) feature a tapered "seat" that matches perfectly with the head that will creates a superior compression seal and with it, maximum efficiency and power. Turbo plugs are the choice for racers who want and need top performance.
Caution : You should never install a turbo plug in a standard engine or vice versa. Doing so may cause serious (and expensive!) damage.
2. Displacement - What size is your engine? Is it .12? .15? .21?
Size matters to glow plugs. Big engines have more mass and retain heat better. Smaller, lighter engines don't, and need the help a hotter plug can offer. Therefore, the smaller the engine, the hotter the plug.
3. Fuel Nitromethane Content - What's the nitro percentage in your fuel?
High-nitro fuels produce more power than low-nitro fuels, but also produce more heat. Hence, the higher the nitro content, the colder the plug.
Smart modelers tend to keep a variety of glow plugs on hand. Simply because the "right" plug for your engine can change with the temperature. To achieve top performance, your choice of plug needs to change, too. Also, the hotter the day, use a colder plug.
5. Other Considerations - A few other things you should know.
Hot plugs promote better idling and acceleration. If your engine runs rough or accelerates sluggishly, a hotter plug will help.
Cold plugs produce more power and may improve performance if your engine runs hot. The downside is rougher idling and more difficulty in tuning.
Where you run also plays a part. If the track/course has a lot of twists and turns, a hot plug is fine. If the track/course has long straights where you'll reach maximum rpm, a colder plug is best.
Fuel-air mix not only affects how your engine performs; it can also have an impact on how long your plug lasts. If you run rich, it means that you're using more fuel than necessary for top performance. Modelers are often advised to run rich during engine break-in, because it helps cool the engine. However, running too rich can also cause an engine to "bog down" or quit entirely. In addition, it also means that the glow element is being exposed to more contaminants than necessary, which shortens plug life.
Running lean means that you're using less fuel. "Leaning down" an engine has a positive effect on performance. However, care is needed here, because over-leaning an engine can harm it, by raising operating temperatures, "burn up" a plug before its time.
Choosing the right glow plug not only improves performance, but can also extend the life of your engine and the glow plug itself. Here are a few more tips for you.
- Buy quality plugs. You're protecting your investment.
- Store plugs where it's dry. Moisture can ruin them.
- Use the right glow plug. Follow the guidelines above.
- Follow proper break-in procedures.
- Tune your engine carefully. Running too lean will make your engine "blow" plugs more often. Proper tuning helps extend plug life.
- Never touch
Airtight is Right
In order for an engine to idle, transition and tune consistently it must be airtight- airtight meaning that no air can enter the engine except through the carburetor intake. Surprisingly, even brand new out-of-the-box high-end engines can have air leaks and until these leaks are found and eliminated, the engine won't run consistently and cannot be precisely tuned. The good news is, several years ago I figured out an easy way to check for and fix air leaks. You'll need the following:
• A small glass of soapy water
• A small brush
• About a foot of fuel tubing
Step 1: Be sure that the high-speed needle is open at least two turns out and the throttle is at fully open.
Step 2: Install one end of the fuel tubing on the carburetor nipple. You're going to be blowing into the other end of the tubing to pressurize the engine crankcase.
Step 3: Place your thumb over the carburetor intake to prevent air from escaping, then blow into the fuel tubing while brushing soapy water around the base of the carburetor, on both sides of the pinch bolt, around the fuel fittings, at the high and low speed needle valves, around the front bearing and even around the back plate.
If any bubbling occurs you've got an air leak. But don't be alarmed. Fixing the leak is easy and your engine will run remarkably better and more consistently when you've eliminated these leaks.
Brushing soapy water around all possible air leak points while pressurizing the case will easily identify air leaks.
The most common air leaks seem to occur around the pinch bolt. Applying a dab of RTV (or silicon) over both exposed sides of the pinch bolt will fix this type of leak. RTV is also great for sealing any leaks around the base of the carburetor. Simply remove the carburetor and run a small amount of RTV around the base of the carb where the leak occurred. Reinstall the carburetor and allow the RTV to ooze out between the crankcase and the carb body. For leaks around the high-speed needle valve fittings, usually retightening the high-speed needle assembly will take care of these. Leaks directly at the high speed or low speed needle usually means there's a damaged O-ring that must be replaced. Many racers don't realize that the front bearing can leak air. That's why nearly every high-end engine uses a rubber sealed front ball bearing to not only keep out dirt, but also air. If your front bearing leaks air, it's time for a bearing replacement.
This simple leak check can easily be done even when the engine is installed in a car. After you've done this test on several engines you'll be surprised of two things: first, how often unwanted air leaks occur and second, how much better your engine runs, idles and tunes when it's airtight. To run right it must be airtight!
Airtight Fuel system
The Fuel system must also be airtight. If the fuel tank, tank lid, fuel lines or filter has a leak then the same kind of tuning issues as described above will occur. While you can check the fuel system by using the same method of brushing soapy water onto the suspected offending area while blowing into the tank, I generally find it better to simply remove the tank from the car and submerse it in a sink of water while blowing into the vent line and plugging the fuel line. If bubbles are present you've got a leak.
An engine at full throttle produces about 6 to 8 psi in the vent line and conversely in the tank. By blowing really hard you're also able to produce about 6 to 8 psi for a couple of seconds. If you're able to blow hard enough to cause the tank lid to open slightly and leak, it's time to replace the tank lid spring or bend more preload in the spring. The entire system (fuel tank, fuel filters, fuel lines, tank fittings, etc.) must be airtight to achieve consistent repeatable performance. I always that my fuel system is airtight when it's new but also recheck it every time I rebuild a car after a race. It easy insurance plus soapy water is a good way to thoroughly clean the tank. Just be sure it's totally dry before using it by flushing out any water left in the tank with fuel before installing it in you car.
Tuning in a Pinch
The pinch test.
Many racers find it difficult to properly tune the low speed needle. We've developed a method that makes it easy, even for beginners, to adjust the low speed needle to within 5% of peak performance and it's done right on the bench. We call it the pinch test and here's how it works.
Step 1: Start your engine and warm it up for about 30 seconds by revving the engine from idle to mid-throttle while holding the wheels off the ground.
Step 2: Allow the engine to idle for 10 seconds. If the low speed needle tuning is so far off that it won't idle, simply bump the idle position higher until the engine will reliably run at a higher idle.
Step 3: With the engine at idle, pinch and hold the fuel line near the carburetor, cutting off the fuel flow and carefully listen to the engine rpm.
If the low speed needle is set correctly, the engine should increase rpm only slightly and then die.
If the engine increases several hundred rpm before dying, then the low speed needle is too rich and needs to be turned in.
If the rpm doesn't increase at all and the engine simply dies, the low speed needle is set too lean and should be richened or turned out.
After doing this a few times you'll get the hang of it, and tuning the low speed needle will become easy. The only way to get that last 5% performance on the low speed tune is through careful track testing. By evaluating the engine as it accelerates from a dead stop or out of slow corners during actual race conditions is the only way to get those last few percent of power from your engine. Variables like the clutch setting, gearing, traction, atmospheric conditions and even the car's weight will have an effect on this last 5% of tuning performance, and the optimum setting can only be reached by careful on-track tuning.
Fine Tuning in a Punch
On high traction tracks instant throttle response and acceleration are the keys to being competitive. To get that last 5% of performance thru tuning, many top drivers and engine tuners use the punch test. Here's how it works.
With the high speed needle properly set and the low speed needle set per the pinch test above, run several laps at race pace to bring the engine up to temperature. Now stop the car at the beginning of the main straight and allow it to idle while you count to 15. At the count of 15, hit the throttle instantly full punch while carefully listening to the engine and note the rate of acceleration. If you did a good job with the pinch test above and the high-speed needle is properly set as described below, the car should rocket off the line with a powerful, crisp consistent engine sound. The trick here is to tune the low speed needle for even greater acceleration and an even crisper throttle response. Do this punch test several times until your very familiar with the acceleration rate (it helps to judge the amount of wheel spin) and the sound of the engine as it accelerates to full throttle. Now lean the low speed needle 1 hour (or 1/12th of a turn) and do the punch test again. Is the engine's acceleration rate and the crisp consistent sound better than in the previous test? Remember judging the wheel spin (the amount the wheels slip during heavy acceleration) is a good way to compare. If it's better or there's no change, lean the low speed needle 1 hour more and try the punch test again. At some point the engine will lean bog (hesitate) off the line during acceleration indicating that you've gone too far.
When you finally find this point through repeated punch tests then leaning the low speed needle one hour each time, richen the low speed needle 2 hours. This will be your engines peak setting giving maximum acceleration and throttle response for the specific conditions of the day. Just remember if you change anything, like gear ratios, clutch settings, exhaust systems, fuel, glow plugs and even changing atmospheric conditions like temperature and barometric will cause this optimum setting to change. Repeat the punch test often and especially just before a heat race to ensure maximum performance during the existing conditions.
The Dreaded Full Tank Lean Bog
If you've done much gas racing, you've probably encountered the dreaded lean bog that occurs right after a pit stop with a full tank of fuel. Right after the tank is filled, for about the next 3 or 4 laps the engine sags (lean bogs) when accelerating off of tight right-hand corners. On most tracks this happens when accelerating onto the straight. Seemingly, the lean bog magically goes away after a few laps but sure enough, after the next pit stop, it frustratingly returns-slowing lap times for several laps once again.
The key to eliminating full tank lean bogs is pressure tube position or adding a pressure reservoir as shown.
To solve this frustrating issue, it's important to understand what's causing it.
Here's the scoop. As the throttle is released entering a turn, the pressure in the tank is now greater that the reduced pressure in the pipe. When the tank is full, some of the fuel sloshes up into the pressure line. The centrifugal forces encountered in a right hand turn further pulls the fuel into the pressure line, causing reduced pressure in the tank. When the throttle is cracked open to accelerate, the engine goes lean because of this reduced tank pressure and hence the dreaded lean bog occurs. The reason it only lasts for a couple of laps is first, as the fuel level goes down in the tank it's less likely to slosh as much into the pressure line and second, as the fuel level goes down there is a larger open space in the tank that's pressurized, maintaining adequate pressure long enough to prevent the low pressure lean bog problem. (If your exhaust system is mounted on the left side, as with some of the latest monster trucks, then this phenomenon will occur in left hand turns.)
Keep the fuel out of the pressure line! That's sometimes easier said than done. We've had the most success by rerouting the pressure line so that as it come off the pressure nipple, the tubing goes to the right side of the fuel tank, then makes a loop on the right side of the tank. This prevents the centrifugal force of a right hand turn from filling the pressure tube. We've also had good success by adding one of the big reservoirs (they look like a big aluminum fuel filter and are available from Mugen or OFNA) in the pressure line. Many manufacturers, like Mugen and Serpent, recognize this problem and are making special pressure pickups and tank lids with large open volumes in the lid itself. You may have noted that many top drivers' cars have several loops of fuel tubing wrapped in their cars and wondered what was the purpose. Now you know. The key to fixing this issue is to experiment with pressure tube routing and, if necessary, installing a pressure reservoir in the pressure line.
Compressed CO2 sprayed directly onto the carburetor is a great way to prevent vapor lock during long main flame-outs.
If you've ever had your engine flame out after a reasonably long run and then found it nearly impossible to re-start, you may have experienced vapor lock. Vapor lock occurs most often in .12- and .15-size engines, especially when they're enclosed in a body with a 1/10-scale gas sedan or stadium truck. Vapor lock normally occurs after the engine is shut off. Heat from the head and combustion chamber transfers through the crankcase, heating the carburetor to the point that the fuel that reaches the carburetor through the fuel line boils off. This makes it impossible to start the engine because it's starved for fuel. The only way to get the engine to run is to cool the carburetor below the fuel's boiling point. If you're sport driving, you can simply wait 5 minutes for the carb to cool on it's own and then restart. If you're in the middle of an important long main, here are some creative ways racers have (including at the world championship level) cooled their carburetors preventing vapor lock:
1. A bottle of compressed CO2 (or air like those that can be purchased to operate airbrushes) with a nozzle attached, allowing cold CO2 to be directed over the carburetor even when the body is in place. We've seen several top-level race teams use this CO2 method anytime the engine flames out to prevent the possibility of a vapor lock.
2. By pulling the air filter and simply dumping fuel from the fuel bottle over the carburetor, usually bringing the temperature back to a tolerable level within a minute. Just be sure to avoid getting fuel on the brakes, radio equipment or tires or you could be in for a bad race day!
Nitro Engine Tuning
MAXIMIZE YOUR ENGINE'S POWER POTENTIAL
So now you can get your engine started on a regular basis, but you're still struggling with the fine-tuning that will score you a win at the racetrack (or bragging rights at the parking lot). Properly tuning a nitro engine can make that difference without jeopardizing its health. It takes time to learn how to really tune your engine, however. There's a certain "feel" to how your car drives and a certain sound you'll come to know when your engine has been ideally tuned. Other cues that you feel and hear tell you what to adjust when your engine isn't running properly. When it's time to tune your engine, there's no substitute for plain old experience. Reading about engine tuning is helpful, but you need to experiment with your engine to improve your tuning skills. The good news is that the following tips will help you avoid some of the pitfalls of fine-tuning and achieve tuning proficiency more quickly.
BASE-LINE MIXTURE SETTINGS
Engine manufacturers often include base-line settings for the mixture needles, so it's wise to start with these. If this information is not provided, then you must arrive at needle settings that will get the engine started. A universal starting point is usually about 1 turn open (counterclockwise) on the low-speed needle and somewhere in the 2- to 3-turn range on the high-speed needle. This varies among engines, but it gets you started running, and then you can make the necessary corrections. After the initial startup, follow the proper break-in procedure, then worry about performance tuning!
The proper sequence for adjusting the mixture needles is hotly debated. When you start to fine-tune the engine, it's generally best to start with the high-speed needle, then set the low-speed. First, however, get your engine running, and keep it running before you worry about race tuning.
During break-in, the engine typically idles a long time, so it's best to adjust the low-speed setting first so the engine runs slightly rich (loading up every 30 seconds or so). It requires an occasional "blip" of the throttle to clear out any raw fuel that has accumulated in the engine. Once break-in is finished, then get the high-speed needle in the ballpark.
Place the car on the ground and accelerate smoothly to give the engine a chance to build some heat. With the high-speed needle in the proper range, the engine should be able to rev relatively well up to full speed once it has been running for a few minutes on the track or parking lot.
A word of caution first: there's a fine line between the perfect tune and a blown or damaged engine. Nitro-engine fuel also contains engine lubricant, so as you get close to dialing in the mixture to where there is just enough fuel to burn and deliver maximum power, you also are close to having just enough oil to keep the engine lubricated. Anyone with experience in tuning 2-stroke engines can tell you that they run best right before they seize or blow up. Our engines are a little tougher and more capable of taking some abuse than bigger 2-strokes, but there's no sense in pushing the mixture settings so lean that you risk damage to the engine. I can't say this too often: get the engine up to full running temperature by running the car exactly as you would on the track or parking lot. The high-speed needle setting depends on the type of driving you do. I'll start with a racing setup.
Racers will tune the high-speed setting to get from point A to point B as quickly as possible. (Performance also depends on a proper low-speed needle setting, but for now, let's concentrate on the high-speed setting.) The best place to race tune your engine is on the track where you run. I prefer to set the high-speed mixture so the car can leg out the track's longest straight section in the shortest time. Estimate the time by "feel" and gut instinct, or use a stopwatch for more accuracy. The high-speed mixture should be set to maximize engine performance for that particular track configuration. A short, tight track may require a main mixture setting just a shade on the lean side to provide maximum power out of the corners. You needn't be concerned about high-rpm performance because the track is too small for the engine to ever reach peak rpm. A long, high-speed track may require a slightly rich main-needle setting. If an engine constantly revs at the upper limits of the rpm range, the fuel mixture should be richened to ensure proper lubrication across the entire rpm range. This slightly rich setting might reduce bottom-end acceleration to a degree, but longer tracks require a slightly richer mixture setting to let the engine rev to its limits without running dry of fuel and oil.
Why is it important to tune the engine to the track? A mixture needle can only provide optimum performance within a relatively narrow rpm range. Anywhere below this hypothetical rpm range, the engine runs slightly rich; anywhere above, it gets progressively leaner. Until we have fuel injection that constantly optimizes fuel mixture throughout the rpm range, there needs to be a degree of compromise with the mixture settings. So, ideally, set the mixture to provide the most power in an rpm range that is best suited to the track on which you run.
Running in parking lots, particularly larger ones with a lot of breathing room, requires unique mixture settings. It's a common mistake to establish mixture settings for maximum punch as though the car will be run within the confines of a tight racetrack and then to go out and run at wide-open throttle (WOT) in a huge parking lot for 5 minutes. This type of running is incredibly unhealthy for an engine to begin with, and compounding the problem with an excessively lean main-needle setting is a recipe for disaster. If you still insist on torturing your engine, the high-speed mixture setting needs to be as much as 1/4 turn richer than typical to provide optimum fuel for the upper rpm range. The engine will be a little softer when accelerating from a standstill, but it's the only way to ensure there is an adequate supply of fuel and oil when running at the upper end of the rpm range. The inherent danger is that this type of running taxes the connecting rod and other engine components to their limits, but having the proper mixture setting will at least delay the inevitable.
The high-speed needle is dialed in, so now let's properly set the low-speed needle. It's important to set it last because it simply regulates the fuel that flows from the main needle at low throttle settings. Lean out the main needle, and you automatically lean the low-speed needle as well. For this reason, it's wise to finish with the low-speed setting.
Again, it's imperative for the engine to be at full operating temperature. There are many methods of testing the low-speed needle setting; one is to pinch the fuel line. When you pinch the fuel line, the engine rpm increase slightly. Keep pinching it, and the engine will eventually stall. If the engine rpm increase dramatically, it indicates that the low-speed setting may be too rich. Or, if the low-speed setting is already too lean, the engine rpm may not increase much at all, and the engine will stall rather quickly. It's a somewhat crude method and doesn't tell you what to expect from the engine on the track, but it will get you into the ballpark.
Another common way is the "see-how-long-it-will-idle" method. The low-speed needle adjustment affects how long the engine will idle. A too lean fuel mixture causes the engine to race and possibly stall, limiting the duration of a steady idle. A too rich low-speed-mixture setting causes the engine idle to steadily drop and eventually stall. The ideal setting allows the engine to hold a smooth, steady idle for 10 to 20 seconds (max), and then the engine rpm decrease steadily because the crankcase loads up with fuel. Why? There are no awards given for the longest-idling engine. If the engine is able to idle steadily for a longer time, then it may start to lean out and heat up during a race and make it difficult to drive the car and keep the engine running. The only flaw in this method is that it doesn't tell you whether you have an artificially rich mixture to compensate for an idle speed that's too high.
A common mistake is to set the idle-speed screw to keep the carburetor open too far. The low-speed needle must then be artificially rich to bring the idle down to a reasonable rpm. The symptoms are similar to a too rich low-speed-mixture setting; there's just a delay in the loss of engine rpm. How do you avoid this? This is also something that becomes easier with experience, but just continue to reduce the idle speed and lean the mixture until you know you can't go any further. Bottom line: adjust the idle-speed screw to suit the fuel-mixture setting, not the other way around.
The simplest and most foolproof method to properly set the low-speed mixture is, again, to do it on the track. Set the low-speed needle so your car gets the strongest launch after sitting still for about 10 seconds. The engine should be able to pull strongly off the line without hesitation. A noticeable hesitation might be the result of either a rich or a lean low-speed mixture; knowing the difference takes experience, but look for signs that help point you in the right direction. How an engine decelerates can tell you as much as how it accelerates. If the engine spools down and rpm drops uncharacteristically low, it indicates that the low-speed-mixture setting is too rich. Or, if the engine takes too long to reach a steady idle and seems to want to keep revving, that tells you the low-speed-mixture setting is too lean. It can also indicate a lean high-speed-mixture setting, but that setting should have been addressed by properly setting the high-speed mixture first.
It will take a little time to get it right. If you make small adjustments and are patient, you really can't do anything wrong. An adjustment you make in the wrong direction is reflected in engine performance; to correct the problem, simply go the other way.
Changing to a higher percentage of nitro fuel sounds like an easy method of developing more horsepower, but it isn't always that simple. Without getting into all the particulars of nitro fuel, I'll just say that there is a point where you can have too much nitro. Adding up to 10 percent more nitro than is typical produces more power, but you have to know how to adjust your engine to accommodate the extra nitro. Fuel-mixture settings need to be slightly richer when nitro content is increased. Also, you may have to increase head clearance by adding an extra head shim. The extra fuel introduced into the combustion chamber increases compression by adding non-compressible matter; this also increases cylinder pressure during the combustion process, which may cause detonation. Detonation occurs when the fuel explodes instead of burning, and that can cause internal engine damage. The extra head shim will likely prevent detonation when fuel with higher nitro content is used.
A final note about fuel: fuel with a lower oil content (for manufacturers that actually disclose the amount of oil in their fuels) should be run with a richer mixture setting. This doesn't so much relate to performance as it does to the benefit of the engine. Conversely, fuels with higher oil content have the extra lubrication that allows a leaner mixture setting with less risk of engine damage. Fuels with a lower concentration of lubricant are intended for competition use by experienced engine tuners. These fuels will make marginally more power because the lubricant that's removed is replaced with power-producing nitro and methanol. Evaluate your tuning ability honestly before you run out to buy fuel with a lower oil content.
A glow plug's temperature range is critical to proper performance. Small-block engines generally use warm to hot glow plugs, while big-block engines use plugs in the colder range. If you choose a plug in the wrong temperature range, you could be chasing the tune of your engine till the sun goes down. Changes of the relative temperature of the glow plug can be beneficial, however.
A combination of compression, heat and a catalytic reaction between the platinum in the glow-plug coil and the methanol in the fuel creates combustion in a nitro engine. Altering the heat range of your glow plug can alter the timing of the combustion process. Nitro engines don't have an ignition system that can be used to advance or retard combustion timing, but a hotter plug that causes ignition a little earlier in the combustion process can have the same effect. "Advancing" the ignition timing can increase overall power output, especially at higher rpm. There are limits, however, and installing too hot a plug causes pre-ignition (detonation) and risks damaging your engine.
It's a challenge to figure out a glow plug's temperature range. Manufacturers don't use a consistent and universal standard to rate the temperature ranges of their glow plugs. You will probably know the temperature of a plug relative to others within a given product line, but currently, no rating system allows comparisons among manufacturers. Here again, plain old experience with a variety of glow plugs will help you to know which are best for the effect you want.
"Reading" the glow plug is a tuning technique advanced by Ron Paris. It suggests that looking at the glow plug tells you something about how your engine is running. The element in a glow plug will turn gray in an engine that is close to the optimum fuel mixture. This method requires a new glow plug, as the element will eventually turn gray regardless of the needle settings; the length of time it takes to turn gray is the issue. Plugs that turn gray in just a tank or two of fuel (running at race pace, not diddling around) indicate a fuel mixture close to ideal but also close to trouble. If the plug stays wet and shiny for a few tanks of fuel, you're in the safe zone; a little rich but safe. When the plug wire gets distorted or broken, however, you're in real trouble. It's a sure sign that the mixture is way too lean, or that there is too much compression and the engine is detonating.
Engines are essentially air pumps. The engine takes air in, mixes it with fuel, and then the mixture is compressed and ignited. The additional pressure created by the burning fuel increases by a factor directly related to the amount of compression: increasing compression increases power output. But there are limits to the compression an engine tolerates. Too much causes the fuel mixture to combust too quickly, and that returns us to the same detonation scenario of an excessively hot glow plug.
The amount of compression is determined by the number and thickness of the shims (gaskets) between the cylinder head and the top of the piston sleeve. Well, it's determined by many other factors, but the only one easily changed is the head clearance via head shims. More shims = less compression; less shims = more compression. Removing or replacing shims with thinner ones increases compression. Some engines have only one shim, so it isn't advisable to run without a shim at all. Moderation is the key. Go slowly, and make small, not drastic, changes that will minimize the risk of damage to your engine. First and foremost, be sure the piston won't hit the cylinder head if you remove a shim (or shims).
You can also change compression with glow plugs. Some manufacturers make a longer glow plug that protrudes slightly into the combustion chamber, effectively reducing the area in which the fuel mixture is compressed. This area is already small, and the little extra space occupied by a longer glow plug will raise compression. This is not the most desirable method, but it can be used on engines that have only one thin head shim. It's unlikely that the longer plug will even come into contact with the piston, but just to be safe, check the head clearance before you install a long plug.
It's a simple fact: for optimum performance, you must retune your nitro engine every time you run it. Anyone who assumes that the needles can be left alone once they have been set is sadly mistaken. An overnight change in weather conditions may prevent an engine from running or may put it at risk of some damage if adjustments aren't made to the fuel-mixture settings. Ignoring an engine's tuning needs compromises its ability to make horsepower. In response to certain changes in weather, equipment and other variables, nitro engines must be regularly retuned.
Temperature: Hot weather requires a leaner mixture setting; cold weather requires a richer setting. Most people assume the opposite because they treat the mixture needle like a thermostat. It is wrong to assume that colder weather requires a leaner setting to keep heat in the engine and vice versa. Cold air is denser than hot air. The denser, colder air packs more oxygen into the engine, so going from hot weather to cold needs a commensurate increase of fuel to balance ratio of fuel-burning oxygen and the fuel itself. The opposite is true in hotter weather. Going from cold to hot weather requires a leaner mixture setting.
Humidity: Humidity is the amount of moisture (water vapor) in the air. Moisture in the air takes up volume that would otherwise be occupied by fuel-burning oxygen. Less oxygen means less fuel is required to maintain a proper ratio of air and fuel. High humidity requires a leaner mixture setting than dry conditions.
Barometric pressure: A barometer measures the atmospheric pressure (generally listed in the local newspaper or on the local weather forecast on TV). Higher barometric pressure readings mean more air is getting into the engine, requiring a richer mixture setting to balance the air/fuel ratio.
Altitude: Altitude is an important factor that most of us ignore, yet it affects the engine's performance possibly more than any other element. The general formula for power loss with increases in altitude is 3 percent for every 1,000 feet above sea level. If you race in Colorado at 5,000 feet instead of in California at sea level, you can expect to lose about 15 percent of the engine's potential power output, if the engine is tuned properly.
Air is thinner at higher altitudes, which means there's less fuel-burning oxygen than at sea level. You might sense a common theme here: less air (oxygen) means less fuel to maintain the proper air/fuel ratio. So, running at higher altitudes requires a leaner mixture setting than running at sea level.
This chart indicates the direction in which you should adjust the fuel mixture when faced with changing weather and other conditions. It assumes the engine is currently well tuned. You could face any combination of conditions listed in the chart; knowing which way to go with the mixture adjustments is half the battle.
Higher air temperature
Lower air temperature
Higher barometric pressure
Lower barometric pressure
Higher nitro content
Lower nitro content
Higher oil content
Lower oil content
Hotter glow plug
Colder glow plug
TUNED PIPE AND HEADER
Anyone who has been around 2-strokes knows that the exhaust system plays a major role in engine performance. Pipes and how they affect performance is a complete article in itself. I don't want to get into the science of tuned pipes here, I'll simply suggest that volume (assuming the pipe doesn't stray too far from convention) determines where the pipe will go to make the best power. Smaller pipes with lower overall volume make the best top-end power, while the fatter, longer pipes with greater volume provide the best bottom-end punch. Selecting the proper tuned pipe can have a very noticeable impact on your application.
Headers can be modified by almost any enthusiast. The length of the header is important to squeezing more power out of your engine. Longer headers deliver better bottom-end power, while shorter headers make better top end. Shorten a header by cutting it with a hacksaw or a Dremel tool. Cut it in 1/8-inch increments, and measure the performance to determine whether any improvement has occurred. Continue cutting until performance levels off. If you need to add back on to the length of the header because you've cut too much and performance is suffering, simply increase the gap between the header and pipe, but don't expose more than 1/4 inch of coupler. If the header is too short by greater than 1/4 inch, just get a new one.
I've spent lots of time trying to chase away a nasty bog in the engine as it came off the line or out of a corner, only to find later that the problem was the clutch. Some clutches are built properly at the factory, but in my experience, most engage too early, which hobbles the engine coming out of every corner. Tuning the clutch to engage at the proper rpm puts more power to the ground than most could imagine.
You'll notice that I have not once mentioned a temperature gauge. The worst thing you can do is to tune an engine to run at a specific temperature. Engine temperature is affected by a number of factors, only one of which is fuel mixture. Weather and many other factors play a role in engine temperature, so tuning to run at the same temperature every time shortchanges the engine's potential to make power. Yes, most engines run in the 200- to 300-degree range, so checking that the engine stays within this range is valuable to a certain extent. As a result of different weather conditions and other variables, however, the same engine when tuned for peak power output can vary as much as 50 degrees. A temp gauge is a reference tool that you should use only to build a data bank of tuning information. A temp gauge should not be used as a tuning tool. Don't tune an engine to run at 230 degrees all the time. Prevailing conditions may require a mixture setting that causes the engine to make maximum power while running at 270 degrees. You'll never know that if you always target the same temperature.
Engine tuning is not a black art; it just takes time to learn the particulars so you can maximize your power plant's performance. Take the time to read and learn, and you will avoid the mistakes most of us made in learning the ropes. I thought I had it licked 10 years ago, but I'm still learning. We never really stop learning; sometimes, we just get too smart for our own good. Experiment a little with some of the tips, and you'll find there's more power to be made with less effort than you thought. Some of the modifications involve a bit of risk; just take it slowly, and use your "noodle." It's hard to make a mistake you can't correct.
There has been many technology changes to batteries in the last few years. These changes are a big advantage to us.
Being able to greatly increase our run times and speed using all the different kinds of electric motors and better batteries. The RC car battery packs usually consist of a combination of batteries up to 6 individual cells. You can purchase these packs preassembled or assemble them yourself.
There are many different types of batteries that you can use for example NiCd (Nickel-Cadmium), NiMH (Nickel-Metal-Hydride), Li-ion (Lithium-Ion) or Li-Poly (Lithium-Polymer).
Each one of these batteries has it's own unique characteristics. The NiMH batteries are by far the most widely used battery in RC car battery packs. But, the Li-Po and Li-ion batteries are quickly gaining popularity.
Now for just a brief description of each different type of RC car battery.
1. They contain cadmium, that can make them hard to dispose of.
2. They suffer from memory effects, which over time makes them lose their ability to hold a complete charge.
3. Can be rejuvenated easily with the correct charging system.
4. They are fairly easy to detect peak charge.
1. They have a higher capacity (milliamps) compared to a NiCD battery.
2. They are not as susceptible to memory problems.
3. They do require a more sensitive peak detection method.
4. They are more environmentally friendly, making them easier to dispose of.
5. They are easy to damage if overcharged than NiCd's
6. They are easily damaged when charging unmatched cells.
1. They have roughly twice the capacity of a NiCd battery
2. They are more expensive, because of the exotic material.
3. Almost all contain a tiny controller chip embedded in each battery that adjusts how quickly they discharge and prevents overcharging.
4. They require a different charger.
1. They are extremely light weight.
2. They are capable of providing nearly twice the power as a Li-ion battery.
3. They can easily be shaped differently to fit into many different nooks and crannies.
4. They do require a special charger.
5. They are very dangerous if overcharged. So extreme caution needs to be used while charging. But, the new charging systems addressing this problem.
6. They are more expensive.
I know all this so far is boring, you just want to know what RC car battery is best for you.
What do all those numbers on each cell or pack mean. The numbers are the batteries Milliamp Hour (mAh) rating.
A Milliamp is 1/1000th of a Amp Hour (Ah). So a battery with a 1500 mAh is equal to 1.5 Ah. This is the easiest way to distinguish a batteries strength or capacity.
So, a battery with a larger mAh rating has a larger capacity. Thus, how long the battery will last before recharging is needed.No matter what the mAh rating is the voltage stays the same. A good way to understand voltage, is it is the pressure of the electric current.
A better way to understand this is think of your RC car battery as a gas tank.
Voltage is how much gas is being used and mAh is the size of the gas tank.
So, choosing your RC car battery and RC car battery packs can be a critical decision for you to make.
No matter what type of RC truck or car you have. They all need batteries.
You need to have them for your remote control transmitter, receiver, electric motor, glow plug starter and starting system (roto starter or starter box).
Batteries are a large investment for you to make. So, learning to maintain them is a very important item in enjoying your RC trucks and cars.
A graphic look at a slide valve three needle R/C Nitro Engine Carburetor.
All r/c nitro engine carburetors are of the slide or rotary valve design.
This pictorial is of a slide valve r/c nitro engine carburetor. A large number of slide valve carburetors are of the three needle design.
A high speed, low speed and idle adjustment needle. There is some variance in this, some use only two needles. While others use three needles, just that the manufacturer's use different terminology.
Now let us take a closer look at a r/c nitro engine carburetor. A graphic guide to all the parts that make up a r/c nitro engine carburetor.
Understanding your r/c nitro engine carburetor is very important.
Learning how to adjust your carburetor to critical in getting your r/c nitro engine to perform correctly.
Note: Tuning the needle Clockwise is lean and Anti-clockwise is rich..
Adjusting the Low Speed Needle (LSN) (The one coverd with the rubber boot, the place your serov links) Adjust tilll you are happy with the initial pickup. Too lean will result in mild or no smoke & will accelerate like a rocket. Once adjusted, all future adjustments should be on the HSN only..
Adjusting the high speed needle (HSN) (the Gold color) is the screw that either lean's or richen's your nitro fuel mixture entering the r/c nitro engine.Adjusting this needle controls the temperature your engine is running at. Plus, it affects the overall performance of your r/c nitro engine. Too some degree adjusting your high speed needle can change how your engine idles. It can be an art or science getting your r/c nitro engine carburetor adjusted properly.
Be patient and only do adjustments in small increments. A 1/16th to 1/4th of a turn. Usually start at a 1/16th of a turn and see how that works and keep adding a 1/16th of a turn till I reach the tune that suits me.
So do take your time and keep notes on what adjustments you are making.
One other tuning factor that affects your r/c nitro engine is the carburetor restrictor.
Depending on which r/c nitro engine you have you will more than likely have two or three restrictors included with your engine.
The sizes of these restrictors will be from small, medium to large.
The actual millimeter size will vary depending on the size and manufacture of your r/c nitro engine carburetor.
The restrictor you use will depend on your driving style and how you have your engine tuned.
Just remember that changing the restrictor will require you to re-tune your r/c nitro engine carburetor.