I was running my OS Max .12TR turbo head yesterday. I finally got it tuned where it is running great! Good smoke, good throttle response, pinch test goes 4 seconds before it dies. I had leaned the HSN for max speed then richened it a little and the NTC3 was running great.

This engine always runs hot. After a couple of high speed runs I playing around doing some figure eights, spinning the wheels, not getting too much air over the head but not sitting still either.

Because it was running so well I thought I would check the temp and it was at 300. I drove it around a bit and it came back down to 270. But this engine runs like crap until 220 and really doesn't run well until about 240 or more. I tried richening it a bit to run cooler, and it did run cooler, but there was a big decrease in performance, so I had to lean it a little.

It seems I found the sweet spot as any richer and it does not run well. I am running a OS RP6 plug. The temp outside was about 78 so not hot at all. Do you think a RP7 turbo plug would make it run a little cooler, or just keep things as they are because it runs so well as it is?

I doubt the plug would help much if any. Try richening the bottom a bit. This can often help keep temps down.

Also, if you are using a closed cockpit body (like a sedan or something), open up some more cooling holes. Cutting out a side window can drop temps 10 degrees. Cut out a hole in the rear window to give the hot air someplace to go.

If all else fails, try a different fuel.

Actually I was running it with no body on. The sedan body I use does have holes in the windshield and back window, I will open up the sides before I run with the body.

I will try richening the bottom end. As it is it loads up in 10 seconds or so if I don't keep blipping the throttle at idle! This thing likes to run! But I will try that and see if it helps keep the temps down. I am running Byrons 20% now, maybe something else will run cooler.

Too bad the different glow plug won't help, I thought it might be worth a shot. Thanks for the advice!

Check out how the Cooling Head (Heat Sink) is Oriented. You want to be able to see the Glow Plug through the side of the Cooling Fins it the direction, (Front to Rear) that allows the most efficient airflow through the Cooling Head. Most current Race Cars run a "Transverse" Engine installation, the NTC3 is an "Inline" or 90* installation. Your TR maybe already configured correctly for your application, but OS engines, (and other MFG's) usually require the Cooling Head to be rotataed for Max Cooling in the Transverse applications. Anyways, check it out, it's worth a shot. Hope this makes sense.

As far I was told OS is named one number highr than most other brands, so a RP6 is like a R5 and yes, that can be too hot.

You can ask the question if a colder plug will help but trying it for a few buch will give you the right information. A colder plug will shift the ignition and will result in a cooler engien, hom much I do not know, just give it a try.

Good point salvador, I bet the head does need to be rotated.

El Salvador - Wow thanks for the great advice. I have had this engine completely apart and never noticed the way the cooling fins are oriented in the head! It is exactly as you said, I need to remove the head and rotate it 90 degrees so that the air flows from front to back! I'm glad there are guys on the forum a lot smarter than I am! I will try that, I am sure it will result in cooler temps!

Yeah I agree, it's worth a shot and even with rotating the head I think I will try both plugs to see which one gives better results. As it gets hot here in the summer I should go with a little cooler plug anyway. Thanks!

Reading back my post I do think I need to learn how to type or my wireless keyboard needs new batteries.

What are you using to measure the temperature?? I have found that temp guns like Duratrax, Ofna usually are 20-30 degs higher than an exergen at the 270 mark.

It does not behave linearly so I wouldn't suggest using that range to correct your reading.

If you are saying that the engine is 270 without a body, usually you can assume it will go up 20-30 degrees with a body on. Like Roelof said, a colder plug will definitely help, and you should check how many head shims you are using and research the net to see what is the stock shims for 20% nitro.

Good point. I was using the Duratrax one but I also have a large laser thermometer I can test it against. The bigger one is just more of a pain to carry but I know that one is pretty accurate. I only have one shim and I replaced it so I am sure that is OK.

Don't worry about the temperature too much; as long as you sees smoke when WOT/throttle, and the engine never 'coughs' (over-heat) after a few laps on a track, it's perfectly okay.

Use the temp gun only for reference like braking-in new engines to determine the engine is 'hot enough' for proper breaking-in.

RC glow engine is a 'mechanical' thing , break-in 5 same engines with the same nitro contents, plugs and same tunings, all will be in different temperatures.