Nitro Kits

Most Common Questions
How fast do they go?
Our Dash will reach about 10-12 mph, the Micro reaches speeds between 10 and 12 mph, our other touring car kits about 25-32 mph. The electric RS4 MT will go between 20 and 25 mph. The various Nitro cars and trucks we produce reach speeds of about 30-40 mph "out of the box" (stock), while various option parts like engines, 2 speeds and aerodynamic bodies will enable them to go to speed up to 60-80 mph.

How much do they cost?
The Dash is our cheapest Ready To Run (RTR) kit, it is about $100 through hobby shops and other retailers (see our Links page). The Dash kit includes everything you need to run it, there is nothing more to buy. The RTR Micro RS4 is about $200 and requires instant glue and 12 AA batteries. Our other electric kits range from $150 to $200 in price, however you will need additional items like the radio, batteries, etc. See the individual kit pages for what else you will need.

How can I make my 15FE into an ABC engine?
ABC means an engine has a chrome-plated sleeve, a much harder material than the nickel that coats the 15FE sleeve. Click this link for our Nitro Star 15SS engine exploded view and parts list sheet. The parts list at the bottom of the page shows you which parts you need, while the exploded view in the top half of the page show you how the parts fit together.

Can you convert (car A) into (car B)?
Many of our kits share common parts and can be "converted" into other types of kits (truck, rally, touring car) with varying degrees of difficulty. We have no official lists of parts to do these conversions, however, use the Search function of our R/C Forum to find instructions for various conversions compiled by our loyal customers.

Why does the Nitro Star 12R engine feel like it loses compression so quickly?

The new coating and the use of an oil ring in these engines means that they feel as though they have low compression when there is no fuel in the engine. When a compression gauge is put on these engines, it will only register 40-50 psi. However, when oil is added to the engine so that the oil ring is filled the compression will jump up to 65+ psi. We are having a number of these engine sent in (about 3-4 per week) where the customer is reporting that the engine has no compression. When we test them, we find that the compression is well within tolerances and that when the engine is ran, it shows no sign of having a worn piston and sleeve. In addition, the coating on the sleeve has a silicon coating that makes it more slippery than chrome, so it doesn't feel like it has as much "pop" even though the compression is still good.

Can I order parts or kits from you direct?
We encourage all hobbyists to order and purchase their items from their local hobby shops whenever possible. If this is not possible, visit our Links page for online and mail order retailers you can order from. Our Buy HPI site has some parts available, however the prices are at "full retail".

Why are prices listed in your catalog if I can't buy direct?
We encourage all hobbyists to order and purchase their items from their local hobby shops whenever possible. Our Buy HPI site is meant for hobbyists who wish to obtain HPI gear that would be too expensive under normal distribution channels, discontinued products and a few "package" deals for engine parts, etc. We are not trying to take the place of your local shop.

What is the next car kit/body/part you will release?
Sorry, we prefer not to release information like that! Sometimes we will give out prerelease information on our R/C Forum, if you pay attention there you might find out some "secret" info.

Can you sponsor me?
At this time, we have a very small team of racers from Europe, Japan and the USA. All of our drivers have won or placed very well in various National championship series, IFMAR World Championship events or work for HPI or our distributors. Instead of spending lots of money on a large team of drivers, we prefer to have full-time employees to help thousands of our dedicated customers, have a more helpful web site, maintain the R/C Forum, offer parts and services on our Buy HPI site and run a series of fun races for HPI customers. You are still free to email or mail your racing resume to us for consideration.

When will more Nitro Star Pro parts and engines be available?
Novarossi makes the Nitro Star Pro engines for HPI, as well as other OEM engines for several other companies. HPI is not the only company who must wait on parts from Novarossi, and if Novarossi is unable to keep up with the demand on their engine production, all of their OEM customers (like HPI) suffer. We try as hard as possible to get engines and parts in our stock to ship ot our distributors, however if you are unable to find replacement parts or engines for your Nitro Star Pro, try engines from Serpent/Mega, Rex, Mugen, RB Concept and other companies that source from Novarossi.

I've ordered ____ part but it hasn't arrived!
There are rare times when HPI parts can be difficult to find, even if you've placed an order. In the past couple of years HPI parts have been easier to find than ever. If you order from your local hobby shop, you will usually get the part you need within 4 days. If it takes longer, your shop's distributor is looking for the part and it will probably arrive within a short time. Sometimes our suppliers cannot keep up with our demands, in which case we will be out of stock and parts supply will be very limited. This happens very infrequently, however.

General Questions

How fast do they go?
Our Dash will reach about 10-12 mph, the Micro reaches speeds between 10 and 12 mph, our other touring car kits about 25-32 mph. The electric RS4 MT will go between 20 and 25 mph. The various Nitro cars and trucks we produce reach speeds of about 30-40 mph "out of the box" (stock), while various option parts like engines, 2 speeds and aerodynamic bodies will enable them to go to speed up to 60-80 mph.

How much do they cost?
The Dash is our cheapest Ready To Run (RTR) kit, it is about $100 through hobby shops and other retailers (see our Links page). The Dash kit includes everything you need to run it, there is nothing more to buy. The RTR Micro RS4 is about $200 and requires instant glue and 12 AA batteries. Our other electric kits range from $150 to $200 in price, however you will need additional items like the radio, batteries, etc. See the individual kit pages for what else you will need.

Can you sponsor me?
At this time, we have a very small team of racers from Europe, Japan and the USA. All of our drivers have won or placed very well in various National championship series, IFMAR World Championship events or work for HPI or our distributors. Instead of spending lots of money on a large team of drivers, we prefer to have full-time employees to help thousands of our dedicated customers, have a more helpful web site, maintain the R/C Forum, offer parts and services on our Buy HPI site and run a series of fun races for HPI customers. You are still free to email or mail your racing resume to us for consideration.

Can I order parts or kits from you direct?
We encourage all hobbyists to order and purchase their items from their local hobby shops whenever possible. If this is not possible, visit our Links page for online and mail order retailers you can order from. Our Buy HPI site has some parts available, however the prices are at "full retail".

Can you convert (car A) into (car B)?
Many of our kits share common parts and can be "converted" into other types of kits (truck, rally, touring car) with varying degrees of difficulty. We have no official lists of parts to do these conversions, however, use the Search function of our R/C Forum to find instructions for various conversions compiled by our loyal customers.

What are the gear ratios of your kits?
RS4 Mini -- 2.13
RS4 Rally -- 2.13
RS4 Pro -- 2.13
RS4 Pro 2 -- 2.13
RS4 Pro 3 -- 2.25
RS4 Sport -- 2.13
RS4 Sport 2 -- 2.13

Nitro RS4 Mini -- 2.16
Nitro RS4 -- 2.16
RTR Nitro RS4 -- 2.16
Nitro RS4 Racer -- 2.16
Nitro RS4 Racer 2 -- 2.16
Nitro RS4 2 -- 2.16
Super Nitro RS4-- 2.16

RS4 MT -- 2.6

Nitro Rush -- 2.61

Nitro RS4 MT -- 2.92
Nitro RS4 MT Racer -- 2.92
RTR Nitro RS4 MT -- 2.92

What is the next car kit/body/part you will release?
Sorry, we prefer not to release information like that! Sometimes we will give out prerelease information on our R/C Forum, if you pay attention there you might find out some "secret" info.

How long can you run one of these cars?
Any Nitro-powered car or truck will run between 5 and 8 minutes on a full tank of fuel. However, unlike electric cars, you can just refill the fuel tank (the engine can be running or stopped), and keep running the car! If you have enough fuel and the radio and receiver batteries last, you can literally run any Nitro car or truck for hours!

What's the fastest Nitro car you have?
The fastest Nitro car we manufacture is the Proceed 1/8 scale racing car. It comes with a two speed transmission that (with optional gears) allows it reach speeds up to 70 mph. However, this is a highly specialized car that is meant for racing on specially groomed tracks, and finding enough room to actually reach 70 mph is rare. This is NOT a kit recommended for anyone new to the hobby or completely dedicated to R/C racing. 

How fast do your other Nitro kits go?
All of our other Nitro kits reach speeds of 25 to 35 mph after the engine is fully "broken-in". This means that after about 10-15 tanks of fuel have been run through the engine, the internal parts of the engine have been conditioned properly and the car can reach its potential top speeds much easier than during the first several tanks of fuel.

Where can I learn more about R/C car engines?
We highly suggest that anyone interested in learning all they can about Nitro engines (technically, model 2-stroke nitromethane engines) visit the tech articles at www.caraction.com. You can use many of these tips to help you find out more!

What do I need to make one of these Nitro kits run?
Some of our kits are available Ready To Run (these are noted by the "RTR" designation). These kits are preassembled and require a minimum of time to prepare for running. Most of our RTR kits include a radio system already installed, and all you need to do is glue the tires on, install several AA batteries (12 are needed) and in most cases paint and cut out the body. Hobby CA glue or instant-cure "Super" glue, glow plug wrench, a can of polycarbonate spray paint and curved polycarbonate scissors or a hobby knife are the only items needed for these kits. If the kit is not equipped with a radio system, we suggest a budget-level AM radio from a reputable manufacturer. Airtronics/Sanwa, Futaba, Hitec RCD, JR Propo, Multiplex R/C and KO Propo are reputable companies that offer quality radio, receiver and servo products. 

Our other kits are available in kit form. These require that you set aside some space to work on, a set of tools (including large Philips #2 screwdriver, small Philips #1 screwdriver and needle nose pliers), plus the items mentioned above (glow plug wrench, hobby CA glue, can of polycarbonate spray paint, curved polycarbonate scissors and hobby knife). Another helpful tool are side cutters. As with our RTR kits that do not included a radio system, we suggest a budget-level AM radio from a reputable manufacturer. Airtronics/Sanwa, Futaba, Hitec RCD, JR Propo, Multiplex R/C and KO Propo are reputable companies that offer quality radio, receiver and servo products. 

You will also need car model engine fuel (see this page for HPI Power Fuel part numbers) and fuel bottle (HPI part #9067).

You will need to have between 6 hours (for an experienced R/C kit builder) to 15-20 hours (for someone completely new to the R/C hobby) to build the cars, so make sure your workspace will be free of interruptions during this time.

Do the cars have reverse?
Our Nitro cars do not have reverse. The clutch mechanism to make a functional reverse-drive transmission is very complicated and at this time we don't have this feature included in our Nitro car and truck kits. Our electric kits can have reverse, with electric kits it is a matter of simply purchasing a reversing type electronic speed control.

I'm new to hobby, I want to race, what do I get?
Great! Racing is one of the greatest ways to enjoy the R/C car or truck hobby. Since you plan to race, you should equip yourself with quality gear that is available at a reasonable cost. Finding used equipment on the Internet, the local classifieds section or at your local hobby shop is a good way to save a lot of money. Just get some advice from an experienced R/C racer who can tell you what to stay away from. 

These are the pieces of equipment we suggest for an R/C newcomer who plans to race Nitro cars: a quality kit that has spare parts readily available and locally supported (our Nitro RS4 2 or RTR Nitro RS4 are two examples); a digital radio set with servos, preferably FM (Airtronics/Sanwa, Futaba, Hitec RCD, JR Propo, Multiplex R/C and KO Propo are good radio companies); a selection of tools (including large Philips #2 screwdriver, small Philips #1 screwdriver, needle nose pliers, glow plug wrench, hobby CA glue, can of polycarbonate spray paint, curved polycarbonate scissors and hobby knife); car model engine fuel and fuel bottle (HPI part #9067).

The Nitro Star 15FE engine included with the RTR Nitro RS4 3 kit is strong enough to keep up with beginning racers on a typical parking lot track, and as you get used to the speed and maintenance of the engine it can be replaced with a stronger engine like our Nitro Star 15SS.

I'm familiar with the hobby, now I want to race Nitro cars, what do I get?
If you've run cars in the past you may already have a sufficient radio system and the tools. You will still need a good kit that can stand up to race crashes while still allowing you to make the fine adjustments necessary to keep up with the crowd. We suggest our Nitro Racer 2 kit for this! 

Because this kit does not come with an engine, we suggest a high-quality engine with moderate power for your first engine. Our Nitro Star 15SS is ideal for this. Most tracks do not require a 2 speed, but if the track you plan to race on is large enough you can install our #72516 Heavy-Duty 2 Speed Transmission. You will also need tires, inserts and a body. Talk with the racers at the track you will race at to find out what tires they suggest and use. Be sure to talk only to the faster racers! For a body, any of our 200mm bodies will be great, but look closely at the differences between bodies like the Alfa Romeo, Dodge Stratus and others. The shape of the front end is very important, because it will determine how much downforce (and steering) the body will generate at that end.

The recently released Nitro RS4 3 Type SS is also a prime candidate for parking lot club-level racing. It features a highly tuned .12 size engine, our new shaft drive chassis and just as many adjustments as the Nitro Racer 2!

Like the advice we have to give to new racers (above), don't feel you must spend extreme amounts of money to "catch up". When you first start racing it's the slow car that does not hit anything that will finish ahead of the fast car that hits everything.

Why did my friend beat me in a race?
This is a common question we get from newcomers to the R/C hobby, who have added several option parts to their cars but "lose" drag or road course races. The easy answer is that adding option parts to your car does not simply make your car faster. 

If you lost to a friend in a drag race, it's possible that your engine is not performing to its highest potential, bad tire traction, higher gearing on your friend's car, your friend may have a two speed transmission installed, etc. There are many different answers and in this case it's impossible for us to answer a question as general as this.

If you lost to someone on a road course track (a track with left and right turns), the most likely answer is that you need to learn how to control your car better or that your car has not been tuned correctly to go through the corners smoothly. This is one of the biggest challenges of racing, whether it is with full-size cars or R/C cars. Driving smoothly is the key to winning any race. To learn how to tune your car, ask other drivers at your track, team up with a racer who has the same car as you, and check out tech tuning articles on different web sites and magazines. A good starting point for a setup is the stock setup that comes stock with the kit. 

Remember: ANYONE can go fast in a straight line. The fastest drivers learn how to tune their cars so they also go fast in the TURNS. 

How do I make my car faster?
The simple answer is to install a faster engine, a two-speed transmission or a tuned pipe and header set. This is the easy answer if all you want to do is drag race or go fast in a straight line. If you race on a road course track, you will have to learn how to tune the car to handle turns better so you can get more laps during a heat or main event. 

Just remember that a faster car is not always better, however a car that is more controllable is.

How can I lower my lap times?  
This is the ultimate goal of any racer, no matter what type of car, truck, buggy, etc. is being driven. If you are just starting out the best thing to do is use the stock setup out of the box for your kit and practice constantly. Practice is the ONLY way to get bet when you are starting out with the R/C hobby. Experimenting with new setups, tires, shock parts, etc. is the second step. Running your car every day is the fastest way to be fast. 

When you can drive consistently around the track without hitting any walls or corner dots, make a change to the car and see what it does. Keep track of the changes and their effect in a notebook. Use our setup sheets provided to keep track of changes and what happens when you alter the setup. Have a friend time your practice runs with a stopwatch so you can see what changes make real progress in lowering your lap times.  

Where can I find ____ part?
All of our parts can be found at your local hobby shop. We maintain a very good list of local shops in our Dealer List page. If you don't have a shop nearby, you can contact a mail order or Internet retailer from our Links page. You can also buy most HPI spare parts from our website. 

Dealers who wish to be added can email us with their complete contact information. Loyal shop customers are also welcome to let us know about their favorite shop that isn't listed!

Will you make a Nitro conversion kit for your electric kits?
Because of the many differences between our Nitro and electric kits, we have no plans right now to make a conversion kit. It is often cheaper to buy a whole Nitro kit than to convert an electric kit totally over to Nitro.

Why do you use Philips head screws/Aren't Allen head screws better?
HPI kits are sold around the world, and in many countries Allen head screws are difficult to find. We want to introduce as many hobbyists as possible to the radio control hobby, and using a worldwide standard screw is one way we achieve this goal.

What is a starter box? Do I need one?
A starter box is a metal box that has a rubber wheel to turn the flywheel of a model car engine. An engine that has a pullstarter installed does not need a starter box, but the starter box can be used on that engine. Most race-tuned engines do not have a pullstarter installed, so they require a starter box. Starter boxes cost between $60 and $100 USD.

What is a glow plug igniter?
A glow plug igniter is a battery-powered spring-loaded tube that fits over the glow plug of an engine to heat up the glow plug until it is red-hot (usually 2-3 seconds is all it takes). With fuel in the carburetor, the pullstarter is pulled or the starter box engages the flywheel. If the engine is tuned properly, it will start right up. Every R/C engine needs a glow plug igniter to start.

What setup should I use?
The "right" setup is entirely dependent on what you are doing with the car. If you are only running in your parking lot or driveway, a higher ride height than what is specified in the kit manual may be best. This would allow you to drive over pebbles and cracks in the road. If you plan to race your kit, see our Setup and Tuning page for some help, and ask on our Pit Board Forum to get tips from racers around the world!

Just remember that if you are just starting to race, the stock setup from the kit and lots of practice is the best thing you can do!

How should I maintain my car?
You can find many tips on maintenance and cleaning in our Maintenance page, which answers questions for both electric and Nitro car owners. Also, see our Links page for R/C magazine websites around the world. All of the major magazines have up-to-date web sites that have articles on maintenance, setups and more.

What tires should I use?
For playing around with your friends, the stock tires that come with your kit will be fine, but just like real car tires, they won't last forever. Eventually they will wear out and you'll want to upgrade to better tires or cool-looking treaded tires. HPI offers a complete line of racing and "fun" tires for every level of R/C. Just see our Tires page and find the type of kit you have to see our complete line-up of optional tires! You can get the same tires that came in your kit or you can get more race-oriented tires, it's your choice. Just read the recommendations on each tire page to find out what will work best.

Are 26mm tires better than 24mm tires?
For most racers, there won't be a huge noticeable difference in performance between 24mm and 26mm tires. In most electric car applications, racers using 24mm rubber tires will find their car handles better than when using 26mm tires, but some Nitro racers find that they are able to use more of the engine's available power when using 26mm tires. The best thing to do is try both and see what works best for you. Remember that different compounds work better at different times of the day, and tire inserts play a huge role in changing the handling of a car.

How do I use the tweak or droop screws?
From our R/C Glossary: Tweak is a condition at the front or rear of the car where one tire has more load on it than the other. For example, if the right rear tire has more weight on it than the left rear tire, the car is said to be "tweaked". This can make the car behave unpredictably, including spinning out in turns, turning more in one direction than the other, upsetting the steering trim, and many other problems.

To check tweak (you should check between each race): 
A) Hobby Knife Method: Set the car on a flat, level surface. Using a hobby knife, lift one end of the car at the center point. Watch closely which tire lifts off the surface first. If both tires lift off at the same time, that end of the car is not tweaked. If one tire lifts off before the other, adjust the tweak (see below), turn the car around and check the other end. Adjusting the tweak using the "hobby knife method" must be done by adjusting shock length. An easier way to adjust tweak is with a device like the MIP Tweak Station (see below).

B) Tweak Device Method: You can also use a device like the MIP Tweak Station to check the tweak. Devices like this set one end of the car level, and puts the other end of the car on a pivoting surface. This lets the device show the tweak at either end of the car, without being affected by the opposite end. If the bubble is level, the car is not tweaked at that end. If the bubble is not level, that end of the car is tweaked. Adjust the tweak (see below), turn the car around and check the other end. Adjusting the tweak using this type of device requires adjusting the shock preload using threaded shock bodies or ride height clips. NOTE: before using a tweak device, use the adjustable legs to make sure the device is completely level, and set the shock preloads to the same amounts left and right at each end of your car.

To adjust tweak: 
a) Using the Hobby Knife Method above, if a tire lifts off the ground first, you must lengthen the shock shaft that attaches to that tire's suspension arm. This requires removing the whole shock from the car, taking off the spring perch and spring, holding the shaft with a pair of needle nose pliers, and turning the shock shaft end so it makes the shaft longer.

b) Using a "tweak device", if the bubble is to one side of the level, add more preload to the same side (by adding ride height clips or turning the threaded shock collar towards the bottom of the shock) until the bubble is level. 

How do you change ride height?
Most HPI car and truck kits come with optional ride height adjustment clips. These clips are shaped like a "C" and have a small tab that you can hold with your fingers or pair of pliers to remove them. Use these clips to raise the ride height, and remove them to lower the ride height. In general, casual R/C car owners should be able to fit one finger under the front and rear of the car's chassis, or have about 7mm or 1/4" ride height. For racing, the ride height is lowered to 4-5mm. For the best performance the front is a little lower than the rear.

Longer fuel lines are also used by racers who try to tune the tuned pipe pressure to the fuel tank, which controls the fuel pressure to the carburetor. This is definitely not suggested if you have not mastered the use of your engine's low end and high end needle valves! You are otherwise wasting your time. 

What type of receiver battery pack do I need?
Any of our kits will accept a standard 4 AA cell battery pack. This is the type that comes with most radio sets. If you don't have one, the battery holder can be purchased separately for a very low price. These battery holders use 4 commonly available AA batteries.

You can also use the more expensive 4 or 5 cell rechargeable battery packs that are available for between $20 and $90 (US funds). Use the "hump" type packs in all of our current kits, they will fit into the same spot as the 4 AA battery pack.

What type of battery charger do I need for the receiver battery pack?
For the rechargeable battery packs, use the overnight charger that it is equipped with or use an adjustable peak-detecting battery charger that is set at a 0.5 to 1 amp charge rate. NOTE: some batteries that are available for Nitro cars are now nickel metal-hydride, and the proper battery charger must be used for this type of battery. Check your battery charger manual to see if will properly charge nickel metal-hydride (Ni-MH) batteries.

If you use the AA holder for a receiver pack with rechargeable AA batteries, we suggest using a standard household AA battery charger. Remember: DO NOT attempt to charge alkaline (standard) batteries!

Can I remove something from the exhaust to make the car or truck faster?
Our metal "can" style mufflers that sit right behind the engine can have the circular metal baffle inside removed for a slight increase in power. Our plastic tuned pipe and plastic side mufflers do not have any parts that can be removed to increase power. If anything is removed you risk melting the pipe which will require a replacement at your expense. The plastic tuned pipe is ultrasonically welded together, so taking it apart will make it will not perform as well as before.

How can I remove foam tires from wheels?
Reusing foam tire wheels can be done if you don't mind glueing on the new foam donuts. To remove the old foams, cut the foam across the wheel and peel away the foam while using your hobby knife to help cut the foam away from the wheel. Hold the wheel securely in a vise or similar location and use a wire wheel on a drill to remove the leftover foam bits. You can also use a bench grinder with a wire wheel and carefully remove the foam from the tire. Be sure to wear eye protection while doing this!

Engines
My engine isn't old but it's "worn out", why?
Things that cause the engine to wear quickly:

Improper air filtration
Running too lean
Not enough cooling
Cheap fuel

The solutions:

Improper air filtration... keep your air filter clean and oiled, upgrade to a high performance air filter if you run in areas with excessive dust. You'd be amazed at the engines that we see come in with dirt all over the inside of the engine. See the KITS--> "Why you need to care for your engine" link.

Running too lean... adjust the carb as often as needed so that you see a nice trail of smoke at FULL SPEED. The 15FE is pre-set and not adjustable on the bottom end setting, so it will always smoke enough at low to mid speed. Running it too lean on the top end will overheat the engine.

Not enough cooling... cut out your body windows according to our instructions. If you don't have enough airflow over the head you won't be able to keep the engine cool. It is highly recommended that you purchase some sort of temperature gauge, engine temperatures over 250F will cause the engine to wear quickly.

Cheap fuel... don't buy $10/gallon fuel that is blended for airplanes. Car fuel is designed for cars, the oil blend is different than helicopters and airplane fuel. Not all car fuels are the same, some have less oil than others. HPI Power fuel has 14% oil, which is a good balance. Too much oil will bog down the engine at idle and decrease performance, not enough oil will make the engine wear more quickly. Car fuel labeled "Race" usually has a little less oil, it is intended for maximum performance at the expense of engine life. If you are driving off-road you really don't need a "Race" blend. The fuel is what lubricates and cools the engine, don't skimp on quality.

Here are some excellent articles that might help: http://www.rcnitro.com/articles

Here are also links to temperature gauges and a compression gauge, both
highly recommended if you plan on racing nitro engines.

How can I rebuild my engine?
Use our Engine Rebuild Walkthrough to show you exactly how to rebuild your engine with an new piston and sleeve. Rebuilding the engine this way is a cost efficient way to get the performance of a new engine at half or even one-third the cost!

What engine should I get/Is this ____ engine good?
Most model car engines available today are of high-quality manufacture. HPI Nitro Star and Nitro Star Pro engines are made especially for HPI and feature a full HPI warranty. Properly cared for and maintained, any engine will last several years and provide many hours of fun in many different kits. Note that any engine will require periodic piston/sleeve replacements. The life of the piston/sleeve set is determined by the nitro content of the fuel you use, air filter maintenance, and other factors.

For beginners, we suggest our Nitro Star 15 or 15FE. For hobbyists with some skills in tuning and running a Nitro car, we suggest our Nitro Star 15SS or 15SC. Racers and expert-level drivers can't go wrong with our Nitro Star Pro 12R SC and 12R RC engine models. Proceed racers have our Nitro Star Pro 21R SC engine available to fit right in the chassis.

We cannot offer opinions on other manufacturer's engines, but feel free to discuss them on our HPI R/C Forum. 

Can I fit ____ engine in my HPI car or truck?
Most HPI Nitro kits will accept .12 or .15 "small block" engines from any engine company. HPI Nitro kits that include the Nitro Star 15FE engine must be fitted with our #A863 engine mounts to fit an optional engine (use #Z543 and #Z517 screws to attach the engine to the mounts and the mounts to the chassis). 

Note that "large block" engines will not in any HPI "Nitro" brand kits. Large block engines use a .21 engine case but use a smaller piston and sleeve to make a .15 engine. Large block engines include the OS 15RX engine. Large block .15 engines and .21 engines are designed for cars like our Proceed.

How can I fit a different engine in my HPI car or truck kit?
For all kits except the Proceed: If you will be installing either a pullstart or non-pullstart engine in the car, you will need these parts:

1. #A863 (Engine Mount Set)
2. #Z543 (Cap Head Screw M3 x 10mm, to attach the mounts to the engine) 
3. #Z517 (Binder Head Screw M3 x 8mm, to attach the mounts to the chassis) 
4. #A801 (Machined Aluminum Flywheel)
5. #A804 (Collet and washer)

For extra handling performance when installing a non-pullstart engine in the car, you can also use this method:

Purchase #A920 (Heat Sink Engine Mount 15mm) and #A926 (Lightweight Flywheel 32mm for Non-Pullstart). The 32mm flywheel MUST be used with the 15mm engine mounts! These parts allow the engine to sit lower in the chassis for a lower center of gravity (CG), which gives you better handling in the turns. 

Note: You CANNOT use the #A920 mounts or #A926 32mm flywheel with a pullstart engine!

For the Proceed: Use the included engine mounts and screws to fit any .21 engine or "large block" .15 engine in the Proceed.

My engine doesn't work, will you fix it?
HPI will only warranty engines that have factory defects. Engines that are damaged from abuse, neglect or normal use will not be repaired. Also, pullstarters, starter components and glow plugs are not covered under our warranty. North American customers click here for the terms of our engine warranty. Customers in other countries must contact the closest HPI branch to them or their country's distributor.

NOTE: If your engine is not an HPI engine, contact the manufacturer or distributor of the engine, or take the engine to your local hobby shop.

How do I stop the engine?
If the engine is tuned properly (not too rich or too lean), it is perfectly safe to let the fuel run out completely and let the engine die. 

If you want to stop running the car before the fuel runs out, use a rag to stick over the exhaust tip to stop the engine. Make sure it is thick enough or bunched up so you do not burn your hand. Do not use your thumb over the air filter to stop the engine, you may push dirt from the filter into the engine.

NOTE: NEVER use your finger or thumb to stop the flywheel of the engine, this is very dangerous and possibly harmful to your hand!  

When I hit the brakes, why does the engine shut off?
Your idle speed adjustment screw is incorrectly tuned. When you apply full brakes, the carburetor opening must not be completely shut off. To adjust the engine's idle speed, see the engine tuning sheet that came with the engine or your kit. Click here if you have lost this tuning sheet. If adjusting the idle stop screw does not solve the problem, see below.

What should I do with the air filter?
The air filter is a critical component of your engine. We cannot stress enough that for proper care of your engine, the air filter must be in proper working order. 

The air filter in all of our Nitro kits is pre-oiled for your convenience, however it must be cleaned and re-oiled after running 2-3 tanks of fuel. To clean the air filter, take the foam filter element out of the rubber boot and use fresh Nitro fuel to rinse the dirt from the foam element. Use your fingers to work the dirt out of the foam. When all the dirt particles are removed (this may take several rinses), squeeze out any Nitro fuel then apply a small amount of foam element air filter oil, which you can purchase from a motorcycle or automotive shop. Install the foam element in the rubber air filter boot, making sure that the foam is fully seated in the boot with no open spaces around it that air can leak through.

Racers are suggested to use a high-quality, high-flow air filter like the ones available from Motor Saver Air Filters. Motor Saver has many models of air filters available, including models to fit HPI Nitro Star and Nitro Star Pro engines. Motor Saver also offers air filter oil in small bottles.

How much smoke should be coming out?
When the car is idling (engine running, car not moving at all), a small amount of smoke should be coming from the muffler or tuned pipe. At full throttle, there should be a large amount of blue-white smoke coming from the muffler or tuned pipe. If you put your hand about 6 inches (15cm) from the opening of the muffler or pipe for a few seconds while the engine is running at full throttle, you should have a light coating of oil on your hand. 

A good rule of thumb is that you should see a good cloud of smoke come from the car's exhaust as it accelerates out of every corner.

Why does my engine stop when the tank is still half-full?
Your engine is running too "lean". Because not enough fuel is getting through the carburetor, the engine runs too hot and shuts off by itself. The high-speed needle valve must be adjusted so more fuel gets to the engine. See the engine tuning sheet that came with your engine for instructions how to tune the high-speed needle valve so it is a little extra rich. 

Why did my engine die when I gave it some throttle?
Your engine is running too "rich". Too much fuel is getting into the carburetor and not enough air. See the engine tuning sheet that came with your engine for instructions how to tune the high-speed needle valve so it is a little extra rich. 

How does the engine work?
The glow plug igniter heats up the glow plug and when the crankshaft is rotated by the pullstarter or starter box, the fuel gets compressed against the heated glow plug by the piston, which is moving up in the engine sleeve. When the piston is at the top of its stroke, the glow plug has heated the fuel to the point where the fuel explodes, sending the piston to the bottom of its stroke to allow more fuel in, which the piston forces up against the glow plug, and the cycle starts over again.

How do I know if my engine is flooded?
The quickest way to tell if your engine is flooded is if when pulling the starter cord, the engine seems to "lock up" and the car lifts off the ground. If this happens, don't pull on the cord any more! This is often called "hydro lock" and trying to pull the cord will break the pullstarter spring, the pullstart string or damage the engine. 

Another way to tell your engine is flooded is if you know the glow plug is new, the battery in the glow plug igniter is fresh and the engine still won't start after many pulls on the starter cord.

How do I un-flood my engine?
There are two methods of "un-flooding" the engine.

The first requires you to use an 8mm socket to take out the glow plug (don't lose the washer!) and turn the car upside down. Pull the starter cord slowly. If the engine is flooded, you will see several drops of fuel fall out of the engine. After pulling the cord a few more times and seeing no extra fuel come out, replace the glow plug and washer, then re-prime the engine properly and it should start right up.

The second method doesn't require any tools, but if the starter cord is locked up, you must not use this method! Close the needle valve (clockwise) all the way, open it (counterclockwise) a few clicks or 1/8 of a turn, put the glow plug igniter on the glow plug, and pull the starter cord. Closing the needle valve cuts off the fuel flow from the tank, and when the engine starts up it will run for a second or two, then cut off. This burns up the fuel that was in the engine. Now you can set the needle valve where it was previously, and re-prime and start the engine.

How can I put a .21 or large block .15 engine in my car/truck?
Most of our kits will not be able to fit a .21 engine. The Proceed 1/8 scale racing car will fit either a "big block" .15 engine or a .21 engine. The Super Nitro RS4 kit can fit a .21 engine, but requires a modification kit which is sold only (in the US) by a company called Bruckner Hobbies. In Europe and Japan, you will need to find another company that makes a conversion kit.

How can I put a 4-stroke engine in my car/truck?
Only our Super Nitro RS4 can fit a 4-stroke engine, and fitting this type of engine requires a special mounting kit which at this time is only available in Japan from a company called Racy. At this time we are unaware of any other company that makes a conversion kit. We have no plans to release a 4-stoke engine conversion for any of our kits.

How do I remove the flywheel?
There are many methods to removing an engine flywheel. The easiest method that will not damage the engine's piston is the "hydro lock" or "hydraulic" method. With the engine out off the chassis, glow plug install and the exhaust header removed, turn the engine upside-down. Use a non-silicone after run oil to fill the cylinder. Turn the flywheel until the piston compresses the after run oil against the top of the cylinder. Now you can turn the engine upright and use an 8mm wrench to remove the pilot shaft. Remember when attaching the pilot shaft on the crankshaft to use threadlocking compound!

What should the engine temperature be?
The "right" engine temperature will vary widely, depending on the air temperature, fuel used, air flow conditions of the body and several other factors. There is absolutely no way anyone can tell you an ideal engine temperature. It is generally accepted that a proper range of temperatures is between 95 and 120 degrees Celsius (or about 205 and 250 degrees Fahrenheit). Remember that this can and will vary because of driving style, fuel nitro content, altitude, ambient temperature, air pressure and many other factors!

The biggest variable of all in measuring engine temperature is where and how the measurement is taken. Your infrared thermometer may be calibrated completely different than ours, or you may be pointing at a different spot on the head.

The 15FE will run fine at temperatures from 200F up to 250F, as long as you have it set rich enough and use fuel designed for cars. You must have a nice trail of smoke coming from the exhaust when the car is driving at full speed. If the engine is running too hot, it will usually
warn you by having an unstable idle. If you notice the idle fluctuating, richen the needle valve a quarter turn counter-clockwise and check to make sure your body has enough cooling holes to allow good airflow over the heat sink of the engine. Always tune the engine when it is fully warmed up, it leans out as it heats up, so a perfectly tuned cold engine will be too lean once it warms up.

In general, the engine will run fine as long as you see smoke at full speed. The engines are much more likely to be damaged by low quality fuel and/or insufficient filtration than they are by getting too hot. If you use fuel for airplanes it could be damaged at lower temperatures because airplane fuel usually has lower oil content. Always buy fuel made specifically for R/C Cars, not "Airplanes, boats, helicopters and cars".

The engine dies when glow plug igniter is removed!
Your glow plug is bad or damaged. It must be replaced with a similar glow plug. It is always suggested that you keep 2-4 glow plugs available as spares at all times.

What is the clanking sound when the engine is running?
If you hear a clanking noise coming from your engine, it might be a problem with the flywheel and not a problem with the engine itself.

This is a brand new flywheel (#A884) that comes with any kit that comes with the Nitro Star 15FE engine.
If you hear a clanking sound coming from your car or truck, your pilot shaft (#A805) may not be tight enough, causing the flywheel to rock back and forth on the crankshaft. The rocking action can cause the inside of the flywheel to wear out.
This flywheel has been completely "rounded" on the inside mounting part. If your flywheel wears out to this point, you will have no power going to the clutchbell and the flywheel must be replaced.

To fix the problem:

1. Retighten the pilot shaft. Inspect the inside of the flywheel (as shown above). If there is little wear, apply threadlocking compound to the crankshaft and reassemble the pilot shaft/clutchbell assembly. See this page for assembly instructions.

2. Send us the worn flywheel, and we will replace it for free. We are working on changing the design to prevent this problem.

or

3. Upgrade to our machined aluminum flywheel and collet. You can order #A801 (our machined aluminum flywheel) and #A804 (brass collet with black washers, to mount the flywheel) from your local shop or a mail order or online retailer. Total price is $10.50 (US).

Upgrading the flywheel will also allow you to install any aftermarket engine. If you decide to replace the 15FE engine in the future, you will be able to use the #A801 flywheel and #A804 collet combination on any engine you decide to buy. Use both black washers on the Nitro Rush and Nitro MT kits (including the RTR versions), and use one black washer on the Nitro cars. We also suggest that you purchase #A863 (Engine Mount Set), plus Z543 (Cap Head Screw M3 x 10mm, to attach the mounts to the engine) and Z517 (Binder Head Screw M3 x 8mm, to attach the mounts to the chassis). Total cost for the engine mounts and screws is about $6 (US). See this page for assembly instructions.

#A801 Flywheel

#A804 Brass Collet and Washers

The stock #A884 flywheel will only fit the 15FE engine and cannot fit other engines.

How do I know the engine is running properly?
Of primary concern should be the amount of smoke that is seen when the car is exiting a turn. There should be a good amount of smoke with every acceleration. Second, the idle of the engine must be stable. Third, the glow plug wire (when checked after the run) should be shiny and unbroken. Fourth, the performance of the engine should be good throughout the powerband. 

Experienced Nitro racers can listen to the engine of a car as it goes around the track and determine if it is running rich (a deeper exhaust note than normal at low RPM), running lean (at full RPM, a cutting out sound) or normal. However, this is only possible when very few Nitro cars are practicing, because the racer must listen very closely to the exhaust note. 

A more reliable way to tell if you engine is running well is to "read" the glow plug (see below).

How do I read a glow plug?
It is easier to "read" the glow plug to determine if the engine is operating at full efficiency. It is usually possible to take out a new glow plug of an engine and look at it closely to see if the engine is running too rich, near full power, too lean, etc. 

Follow these instructions to read a glow plug:
Using a new glow plug, install it in the engine you want to test. Make sure the wire of the plug is shiny and still new. Run the engine for a full tank of fuel at race speeds.
a) Engine running rich: wire and bottom of plug wet, wire shiny
b) Engine running at almost full efficiency: wire and bottom of plug mostly dry, wire slightly gray
c) Engine running at peak efficiency: wire and bottom of plug dry, wire gray
d) Engine too lean: wire and bottom of plug dry, wire out of shape (not coiled)
e) Engine FAR too lean, possible danger to engine!: wire and bottom of plug dry, wire broken or burned

Some glow plugs turn gray sooner than other plugs, watch out for this if you use plugs from different manufacturers. To test plugs (from your toolbox) you are unsure of, switch glow plugs after running a good plug. If there is no difference in performance, save the plug (put it in a plastic bag or box marked "Used Good Plugs").

Fuel
What kind of fuel should I get?
We recommend a high-quality, brand name fuel made especially for cars. Model fuels for airplanes or helicopters will not work properly and will ruin your engine. HPI Power Fuel is available in both quart and gallon sizes for the hobbyist (in 20% nitro content) or the serious racer (30% nitro content). See our Nitro Option Parts page for part numbers of HPI Power Fuel.

What is after run oil?
After run oil is a special oil that is meant to be used when an engine is to be stored for more than a week and not run. It is suggested for all Nitro car or truck owners. It usually costs between $3 and $5 (US). You can also use Marvel Mystery Oil (US brand oil), 3in1 brand oil (US brand oil), or automatic transmission fluid as a substitute. 

How do I use after run oil?
Take off the air filter and glow plug, and drop about 5 drops of after run oil into each opening. Pull the engine pullstarter a few times, or rotate the flywheel several complete rotations (pull the pullstarter spring or turn the flywheel on a starter box) to cycle the oil throughout the engine's internal parts. We highly recommend using after run oil on any engine that you do not plan to run for more than a week. 

You can also use Marvel Mystery Oil (US brand oil), 3in1 brand oil (US brand oil), or automatic transmission fluid as a substitute. 

NOTE: Do NOT use a lubricant like WD-40 on the internal surfaces of your Nitro car engine! It is not designed for use inside 2-stroke engines. Also, DO NOT use any oil that contains silicones.

Do I need break-in fuel?
We have not found any special properties or advantages of using these break-in fuels. We use and recommend regular fuel to break in engines, using the same nitro content and brand fuel that we will run in the engine when racing.

What if I run different nitro content fuel?
If you plan to change the nitro content of the fuel used in a particular engine, it is highly suggested that you follow the short version of the standard break-in procedure using the new fuel (one or two tanks at a rich setting, with the car on a stand). After this is complete, cautiously run the car at slow to medium speeds for one full tank. Check the glow plug to make sure it's okay. If everything seems fine, run the car normally.

What if I run a different brand of fuel?
If you plan to change the brand of fuel that you use in a particular engine, it is highly suggested that you follow the short version of the standard break-in procedure using the new fuel (one or two tanks at a rich setting, with the car on a stand). After this is complete, cautiously run the car at slow to medium speeds for one full tank. Check the glow plug to make sure it's okay. If everything seems fine, run the car normally.

Pullstarter
The pullstarter string does not go back in!
Gently tug on the string to see if the spring inside the plastic pullstarter housing retracts the string. If it does not, stretch out the string in a straight line and turn the flywheel back and forth a few times. The string should very quickly pull back in the pullstarter housing. If it does not, the pullstarter spring is probably broken and must be replaced. HPI does not warranty pullstarters, however replacement pullstarters can be ordered and purchased from any hobby shop or hobby retailer. The pullstarter for the Nitro Star 15, 15FE, and 15SS engines is part #1668.

Why won't the pullstarter pull all the way out?
The pullstarter should only be pulled out about one foot (30cm) to start the engine. It is able to pull out up to 2 feet, but this extra length is only slack to prevent damage to the pullstarter spring. 

If you cannot pull the string out even one foot (30cm), the engine is probably flooded. Click here for instructions on how you can "un-flood" the engine.

Clutch
My tires start spinning when the engine starts!
Your idle speed is too high and/or your clutch shoes have melted to the inside of the engine's clutchbell (the black metal gear attached to the engine). 

To adjust the engine's idle speed, see the engine tuning sheet that came with the engine or your kit. Click here if you have lost this tuning sheet. If adjusting the idle stop screw does not solve the problem, see below.

When my car comes to a complete stop, the engine dies! 
Your clutch shoes have melted to the inside of the clutch bell. See below.

The wheels on my kit don't turn forward, even when I give it throttle! 
With the engine not running and the brake lever not engaging the brake, push your kit in a straight line. Your kit should roll at least 5 feet before slowing to a stop. If it does not, something is stuck or rubbing (binding) somewhere. Inspect the tires, dogbones, axles, diff areas, everything that rotates for anything that may be slowing the car down.

You should also be able to turn the clutchbell (the gear attached to the engine, just in front of the large circular flywheel) with your fingers. If the flywheel turns when you try to turn the clutchbell, your clutch shoes are probably melted to the inside of the clutchbell.

Remember also that your engine must be tuned properly - If the engine is new and too rich (more than 3 turns open) the engine may be bogging down from too much fuel, try leaning out the engine (lean = rotate the needle valve clockwise) until the engine runs properly. The Nitro Star 15FE should run fine at about 2 1/2 turns. Don't set the needle valve at less than 2 turns unless you have a way to measure the engine temperature. Anything over about 250 degrees F is too hot. Always run the engine a little bit on the rich side, when the engine is properly tuned you should see a nice trail of smoke from the muffler when the car is driving at full throttle.

Why did the clutch shoes melt?
The main reason for the clutch shoes melting to the inside of the clutch bell is the engine's idle speed was too high. If you have to use your foot or a curb to stop the car when it's supposed to idle, your idle speed is too high and the clutch shoes will melt eventually. When you have the brakes applied, the clutch shoes are still expanding and contacting the inside of the clutch bell. This contact (friction) creates heat, and although the clutch shoes are made from a heat-resistant plastic, the clutch shoes eventually melt into one solid mass and prevent the springs from bringing the clutch shoes into their normal position.

To solve this, you must remove the engine from the car chassis, take the clutch bell off the engine, and remove all the melted plastic from the inside of the clutch bell. Replace the clutch shoes and springs with their stock replacement parts (#A827 and #A808) or our Nitro Racing Clutch (#A885), which resists melting. Then correctly adjust the idle stop screw according to your engine tuning sheet. See your kit manual or the engine tuning sheet for the correct installation of the stock clutch shoes. 

At idle, the car (with receiver and transmitter turned on) should have its engine running at low rpm with no movement of the car.

Gears
Why do my spur gears keep stripping?
Stripping a spur gear (a flat spot on the plastic gear that turns the drivetrain of the car) is not caused by the spur gear or pinion gear. A stripped spur gear is caused by the pinion gear not having the correct mesh with the spur gear.

How can I get correct gear mesh?
The easiest way to learn that you have the correct gear mesh is to use a piece of paper and fit it between the spur gear and pinion gear as you tighten the motor mount screws. After the motor is completely tightened, the piece of paper should be impossible to remove except by turning the spur gear to rotate the paper out of place. With the paper gone, turn the spur gear with a finger and feel the amount of movement or "play" there is between the spur gear and pinion gear. There should be very little play, but you should feel a little bit. This is the correct gear mesh. With practice, you will no longer strip any spur gears. 

Make sure the motor mount screws are very tight, a big crash could move the motor towards or away from the spur gear, making the spur gear strip out.

NOTE: Some of our Nitro car and truck kits feature "static" engine mounts, so the engine will not move and the gear mesh is set perfectly with the stock gearing. If you change clutch bells on the engine, we suggest you use these parts so you can adjust the gear mesh properly:

1. #A863 (Engine Mount Set)
2. #Z543 (Cap Head Screw M3 x 10mm, to attach the mounts to the engine) 
3. #Z517 (Binder Head Screw M3 x 8mm, to attach the mounts to the chassis) 

What does a slipper clutch do?
A slipper clutch is a device that fits on or near the spur gear, and helps absorb "drivetrain shock" that occurs when a car lands from a jump. A slipper clutch also helps aid traction in slippery conditions, since it acts as a mechanical way to limit the power that reaches the drivetrain. 

Why do you not recommend 2 speeds for off-road or reverse?
Every 2 speed uses special, very expensive bearings called "one-way bearings". If these one-way bearings have dirt, dust or other materials in them, they can be ruined very quickly. Running any R/C vehicle off-road gets dirt and dust all over it, and a one-way bearing is easy to destroy in a dirt-filled environment.

Jumping and using a reversing Electronic Speed Controller will also make the one-way bearing turn in a direction it was not designed to do, and could damage it.

For these reasons, we will not repair or replace any one-way bearing that is used off-road or in a vehicle that used or uses a reversing ESC.

Option Parts
What options should I add/What is the best option part to get?
This depends on what you are looking to achieve from your car or truck kit. If all you want is top speed, a set of the right spur and pinion gears and a fast, high-horsepower motor will satisfy your urge. If you plan to race your car, a set of the "right" tires (ask at your local track) will help out the most. Sometimes you just have some money to spend and want to make your car look nice. We offer purple aluminum parts for all of our kits, which help make the car much brighter and can strengthen it as well. If you need to tune your car for racing, a set of shock towers with extra mounting holes, a graphite chassis to replace a stock chassis. See your kit's option parts page for a complete list of option parts that will fit your car or truck.

My 2 speed is not shifting!
Unless something is not adjusted properly or broken, the 2 speed should shift into second when the engine is sufficiently warmed up (usually a minute or two of starting the engine). If it does not shift, use a 2mm Allen wrench to adjust the shift point set screw counterclockwise. Turn the set screw 1/4 turn at a time and make a test run to see if the car shifts into second. If it does not, turn the set screw 1/4 turn more and try again. Make sure not to touch the center set screw! The center set screw holds the 2 speed in place on the gear shaft.

How do I put a different tuned pipe on the car?
If your kit has a side muffler or tuned pipe already on it, you simply need to purchase a tuned pipe, take off the old muffler or pipe, slip the new pipe into the silicone tubing from the header pipe and attach the main body of the pipe to the chassis. Most tuned pipes will have a way to attach the pipe to the chassis. If not, contact the manufacturer of the pipe or see your local hobby shop for help. 

If you kit has a rear-exhaust muffler (the Super Nitro RS4, Nitro RS4) you will need to purchase a header in addition to the tuned pipe. Owners of our other kits will not need a header, but a header will increase efficiency and power over the stock header included in the Nitro Rush, Nitro MT, Nitro RS4 2 and other kits.

Do you make a rear exhaust kit?
At this time we do not make a rear exhaust kit for any of our cars, however you can use our #A870 "can" type muffler to simulate a rear exhaust. This replaces the stock side exhaust on our Nitro car kits. The #A870 muffler comes stock on the Super Nitro RS4. With T-connectors and wide silicone tubing you can make a convincing dual rear exhaust!

Why do you not recommend 2 speeds for off-road or reverse?
Every 2 speed uses special, very expensive bearings called "one-way bearings". If these one-way bearings have dirt, dust or other materials in them, they can be ruined very quickly. Running any R/C vehicle off-road gets dirt and dust all over it, and a one-way bearing is easy to destroy in a dirt-filled environment.

Jumping and using a reversing Electronic Speed Controller will also make the one-way bearing turn in a direction it was not designed to do, and could damage it.

For these reasons, we will not repair or replace any one-way bearing that is used off-road or in a vehicle that used or uses a reversing ESC.

Radio
What radio should I get?
Radios are a vital part of the R/C equipment list. You should prepare to spend a good portion of your R/C budget on a radio you are comfortable with. For most newcomers to the hobby, an AM radio is sufficient for having fun and adequately controlling a car or truck kit. Most R/C radio companies offer AM radios. If it's possible, try to find a low-priced FM radio, preferably with a digital or computer controller. JR Racing and Hitec RCD both offer reasonably priced FM radios. As you get more experienced or obtain more car and truck kits, you may want to get a digital radio that can hold settings for several models. Airtronics/Sanwa, Futaba, Hitec RCD, JR Propo, Multiplex R/C and KO Propo are reputable companies that offer quality radio, receiver and servo products. They also make Electronic Speed Controllers!

What are these different bands (27, 40, 75, etc.)?
Every radio and receiver set transmits in a specified range of radio frequencies, generally called a "band". Each country has a set of laws that defines what is legal. For instance, 40 band radios are allowed in some European countries and Japan, but not the United States. 27 band is the most popular to use because it is usable worldwide, however the fewest number of frequencies are available in 27 band (12 in Europe and Japan, but only 6 in the US).

My car is glitching/I can't control my car!
The first thing you should do before starting to run your car is make sure no one is on the same frequency as you are. In the US, frequencies are labeled with a simple number. In other countries, most racers use the last digits after the decimal point to identify the radio frequency they are on. Before running your car you MUST make certain that no one else will be interfering with the radio frequency you are using.

After making sure you are on a clear frequency, check these items, in order: radio antenna fully extended, radio batteries fully charged or fresh, the receiver antenna wire is not touching graphite or metal items, the receiver or transmitter crystal is not broken, the receiver is mounted as high as possible on the chassis, or finally the receiver is mounted so the crystal is as far above the chassis as possible. 

If none of these help, contact the manufacturer or distributor of the radio for support.

Some information on engine tuning and maintenance has been borrowed from the Paris Racing website.