Should I Port my Radio Control Car Nitro Engine?

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Should I Port my Nitro Engine?

Here is a very good question that was sent to us by Rob regarding his 12 size nitro engine. This would usually go in the "Answers From The PRO" section but I thought it was so important that I would put it here. Enjoy!

Comments: I'm 16 years old and just got my new RC10GT. It has a .12CV in it and I know people have ported the exhaust pipes but I want to know how to port my engine. Can you help me do this? It will be for more power at low end.

thanx

Rob,

DO NOT, I repeat, DO NOT port your engine. You will ruin it. O.S. max engines spends hundreds of thousands of dollars a year on research and development to ensure that their engines are providing the most power output while burning the least amount of fuel. O.S. knows more than you or I will ever know because they have tons of money to get this knowledge. I have personally raced with people on the O.S. racing team and not one of them have ever changed anything on their motors to gain power. The O.S. 12CV is an amazing engine, it wins races all of the time (from what I have seen at the major races, the 12CV always dominates the A main).

Now for the solution to your problem. A nitro motor is a closed system. This means that given it's inputs (in this case fuel) it can only provide a certain amount of output (in this case power). If you are looking for more bottom end power you will have to loose something to get it. That something will be top end power or your top speed.

Before we get right into how you can increase your bottom end I want to refresh your memory on air fuel mixtures. A lean mixture (turn valve clockwise) makes your engine run with more power but it will run hotter (less fuel and oil to cool the engine) while a richer mixture (turn valve counter clockwise) makes your engine run with less power but it will run cooler (more oil to cool the engine). To properly set up a nitro engine it must remain below a certain maximum temperature. This maximum temperature is different for each engine and a little experimentation is usually necessary to find it.

With this in mind the only way that you can increase your bottom end power is to lean out the bottom end mixture while you richen up the top end mixture. This will allow the operating temperature of the engine to remain the same while it transfers the power band into the lower end of the throttle. This will increase your acceleration and make the car more snappy while it will reduce the top speed of the car. This is usually a good setting for smaller tracks with tight turns or many doubles or triples that require quick low end power to clear them.

I personally run my nitro engines with a very lean bottom end and a slightly richer top end because I like a car that is very twitchy and hard on the acceleration. You may find the car harder to drive but when you learn to control it, you will be a better and faster driver.

One last point going back to the porting of your engine. As I mentioned earlier, your engine is a closed system. If you port your engine to gain more power (which is possible) you will loose fuel economy. This means that a fuel tank will not last for 10 minutes but maybe for 8 or even less. The point is that the engine manufacturer has provided you with the most power available without compromising on the amount of run time available to you. An engine with more power may go 2 tenths of a second faster per lap but will this cover the extra two or three 10 second pit stops you will have to take to finish the race?

I have been racing 1/8 scale off road nitro for about 5 years now and I have never once felt the need to tamper with my motor. I have also personally seen Chris Moore (an old Kyosho USA and O.S. max team driver) pull a brand new O.S. 21 RZB out of the box and put it into his car to be raced in the A main at the Kyosho World Challenge without anything close to a modification done to it. If you want to make modifications to change engine performance, try experimenting with headers and tuned pipes. Change the lengths of the pipes or even the brands to find out what works best. Try different fuels or glow plugs. Run a high quality air filter and keep it clean. Change you clutch settings to alter when it engages. Play with your radio, try some exponential or other functions available today. My point here is that there are many useful changes you can make to your nitro car to increase performance but opening up your engine and going crazy with the dremel is the absolute worst thing you can do. If you are rich (and most of us aren't) try it and you'll see for yourself.

I hope this helps you.

Let's take off a few tenths per lap,

"PRO"