Anyone here race Nitro RC Cars?

[Jolane]

Just Curious. I thought I would take a small break from working on the Z. This time it comes in the form of RC cars, 1/8 scale buggies to be exact. Having flown RC airplanes for the last 14 years, I thought I would do something different (and I can do this in the street in front of my house).

My question: I have broken in the motor (.21 TOP Engines P5). Now I need to figure out how to properly tune the engine. I know to let the chassis warm up, and change the glow plug (using McCoy), but how do I know if the engine is rich of lean? If it is smoking, is it definitely rich, or is it just the fuel type? There are three adjustments, idle, mid-band, and high-band.

Thanks for any and all help.

Joshua

 

BTW, this engine is in a Mugen MBX5 Prospec with extra hop-ups, has KO Propo Digital servoes for steering and throttle, and is controlled with the JR XS3 Pro radio (Synthesized). Wow this is a fast little car!

[Rival5]

First I'd recommend an IR temp gauge and find what your normal temperature range is for your engine. Over heating can quickly kill the engine. A thin trail of white smoke from the exhaust is what your looking for with a strong high pitch whine at full speed.

 

 

Found this pdf from Team Associated http://www.teamassociated.com/shusting/CatalogHub/engine/AE15_engman.pdf

smaller engine but the tuning should be the same.

I have a Nitro RC10GT and an electric Losi XXXT.

[BillZ260]

Havn't had any experience w/ these, but I am working on an RC rocket boat...so I can tell you once you get the engine tuned, get a rocket w/ the about the same amount of lift that your RC buggy weighs and it will...fly...

[cygnusx1]

I have built two .21 RC allwheeldrive offroad buggys. When it's rich, it fires on every other cycle (lower pitch) get it so that it switches over into the firing on every cycle (higher pitch). Take it for a good hard run and then spit on the head or use a drop of water. The water should boil off the head slowly. It should sizzle off gently in about 3-4 seconds. If it's too lean, the water will sizzle violently. Smoke is also a good indicator as stated above.

[jaime240z]

Woohoo....My other addiction! I love nitro r/c. Unfortunatley I had to sell my nitro buggy recently (no time to play) but I still have plenty of cars in my stable!

 

Definitely invest in a good temp gun. This will be your best friend when tuning a nitro engine. I've always kept my engines in the 230-250 deg range. After break-in, you will want to start leaning out the high end needle first. Do this with the car rolling on a flat straight surface. Make small clockwise turns to lean it out until you're getting good WOT accleration. Don't worry if the low end stutters or dies. It will do this naturally since the low end is still rich. Remeber to make small moves closed on the needles. I would say no more than 1/8 turn at a time. Remember to check the temp regularly. You will want a nice trail of smoke on WOT. This means the engine is still able to be cooled. If no smoke is visible at WOT then you're probably too lean and need to reset you HSN setting.

Once the high end needle is set move on to the low speed needle. Lean it out slowly until your car is snapping off the line without stuttering or dying. It should be obvious when the performance is gets better and better as you lean out the LSN. Once again keep a close eye on engine temps.

Finally you will want to adjust the idle. I always set mine a bit on the high side to keep it closer to the power band off idle. Once everything is set give it a good run on a full tank of fuel, checking temps often to make sure it's not lean.

 

IIRC the P5 also has a mid range needle....? These are usually factory set and you shouldn't need to adjust the MSN.

 

You're going to love the P5. I had the RB WS7II in my hyper7 and it was crazy fast. The P5 was to only other factory (non mod) engine that could hang with the WS7II.

 

If you're not already on there check out the forums on www.rctech.net I've found that sight very usefull.

[stony]

I ran a .21 motor in a 10th scale rorad car. i had a digital temp gage and gun and they were both really close (within 5 degrees.)

 

agree with all above. i tried the water method but still blew a motor. thats when i envested in the gage and gun... never had an issue with it after that. ran like a raped ape. damn those things were fun. mine had a 2 speed ttranny and got up to 50MPH on teh back straight!!!! i wasnt pretty when there were wrecks either

 

Oh yea running with the body on and off made a huge difference in temps so make sure you tune they way your gona run it.

[Guest TegRacer324]

I have a Duratrax Axis. I think that's what it is. Haven't used it in a while. It's a .21 1/8th scale buggy. It's fast as hell I'll tell you that, but it does get kinda boring after a while. The engine in that thing I think it's a Torq sucks ***. The thing has cooked on me twice and they told me it was my fault even though I went through break in and proper tuning each time. I think overall planes are more fun, but the car is definately fun too. The engines run much much hotter though and are more finicky tuning than a plane. What do you have for planes? I got about 8 of those damn things and a heli layin around. I really gotta get back into it. Haven't flown em in a couple years.

[Jolane]

Thanks Everyone for the tips,

I have had a few chances to try to tune the thing again, and was still having problems until yesterday afternoon, when I noticed that fuel was leaking out of the carb banjo/barb fitting. Once I tightened that, it ran a tone better. I hope I did not do any damage though. I do have good compression, and the thing is very fast. I do have an IR temp gauge, but I have read that those can be way off. I am going to pick up a contact probe today for a more accurate measurement.

TegRacer324,

I have a few airplanes left (~5). I have a not flown in over a year. My latest project, before I stopped building, is a 1/4 scale Extra with an O.S 1.60. I have pretty much everything for it, and most of it is built, I just don't have the room (or time) anymore. Thus the reason for a car. It takes less time, and I can play with it for an hour in front of my house if I want. My next R/C toy will be a heli (Thunder Tiger Raptor 50 most likely).

Joshua