Yes the ever asked question of "what temp should my engine be?"

now I know the answer is "tune to performance not temp."

However, what is the temp that no matter what is too hot? With my current engine which is a JP Modified Mugen x12, what temperature should I stay below? Looking for more concrete info other than "if it sounds and feels good then it's good." basically after running a few passes at high speed and bringing the car in I get temps around 260F and wanna know if this is safe. I can richen up a bit to drop temps right?

Thanks for any replies.

250 is a nice place to be at, i would say keep it within 10 degrees of 250 and you should be just fine.

I agree with randay. As long as the engine is running well, I try to make sure it's in the 240-260F range. Less than 240 and I would say I'm running too rich. More than 260 and it should begin to sound too lean. 300+ is bad, although the CRF can handle 300+ without blowing up on you or burning plugs in 4-5 minute heats.

BTW ... I am by no means advocating running a CRF at 300+ degrees.

Ok then I will richen it up a little bit and make sure it stays below the 260 mark.

someone does it like this;
use thrumb to stop the engine at idel at flywheel, let it cold down, take out the plug, stamp the plug onto our hand or palm, you will see a ring by the fuel. The more wet it is, then it tells you there is still room to lean.
But make sure you observe the temp and having enough smoke.
just my 2 cents

The hotter the better . If youre tuning for racing you cant rely on smoke out the pipe as a sign.. Different fuels will smoke more or some less, some not at all.

Many things determine the race temp on an engine so its a very broad question to answer.

I rarely temp my engine , i tune for performance till it chokes. I get just over 9 mins tank time in my MTX3. Ive run over 15 litres through it like this hitting temps in excess of 160 deg C the engine still has great pop .. Thats running 7% oil total..

Anyway i hope this helps some

Cheers MM

Mark are you mad??. The guy asked a simple question Ya shore you can run engine like that. But under normal use you would stick around the 240 to 260 deg f and 120 to about 130 deg c for a 12 size engine. A .12 engines normaly runs hotter than a .21 engine i try to keep my 21 engines around 100 to 125 deg normaly about 110 or there abouts. Regards Jeremy.

Usually you want your engine to run around 160-170F more than the ambient temp is.
For example if it's 60F outsite then the safe engine temp is around 220-230.
If it's 90F then 250-260.
But this is all theory since the engines cooling head, the body, the gearing, the track,... all affect the engines temps.

Of course you can't run it for 5 minutes and say it's OK at 250 that it temps now and later on you go and run a 40min final and expect it to stay there...!!

There is also a point where the metals of the engine will start to wear out much faster at a given temp which for each engine this differes.

Tuning by temperature depends on alot of variables. Temp Guns as well. I have seen temp swings of 40 degrees F between guns. Also the method on how someone temps it is another factor. I use an Exergen 501, and try and temp it the same way each time. I make sure the cone is perpendicular to the head entering the cooling head.

If you use a temp gun.........use the same one each time. It will help you gauge a baseline reading on that motor.........and that particular day's ambient temps. For mains, you might want to start the motor a tad rich. Perhaps an hour or two richer on the top end. Many motors will come in 20 to 30 degrees hotter after ten to fifteen minutes of hard running. If your on the threshhold of too lean before a main........you might come in overlean during the main.

I know this topic was about specific temp...........but some motors run great at 240...........some won't even get out of there own way unless at 280(.12's that is). Depends on the motor.

tune the engine by performance ,not all by temperature,

Here in Hawaii, our temps are usually between 80-90F, give or take 5. That's why randay and I would say 240-260F.

Now days, given the different head designs and materials, it's hard to gauge what is accurate anymore - and you have to have a very accurate temp gun.

Our humidity swings quite a bit throughout the day. You have to fuss with the engine quite a bit. We only get 3 minutes of warm-up on the track to figure out how the humidity has changed the tune of our engines and then figure out how much to turn the HSN just before the start of the race. If you know your engines well enough, you can guess-timate what the settings should be on the starter box. If you don't know your engines, guess-timating can be a bad thing.

IMO, temp-ing is good to help tune your engine, but should not be the only means by which you tune your engine. Tune for performance first and then make sure you're not about to blow up your engine by taking the temp. Well, that's how I do it.

It's true you can't tune for performance and worry about temps...it will always be high...at least in most engines and most places.
That's why engine manufacturers keep increasing the size of the cooling head.
For example the new O.S. speed, the new O.S. VG, the RB S3, Radical, SH, ...
You can't have the same cooling head for all over the world.
In very cold climates you might need a head of an on-road engine...and on hot climates you might need an off road head on an on-road engine to keep the temps down.

You have to make sure that you have the right cooling head for the climate you race at.IF you care about your engines...!!!
The best case is to have the temps at a safe level and still be able to tune for performance.

I normaly tune my engines to i have a good paformance and then do a few laps and just check the temp if i feel its to high for the condishions ill ritchen it. you can not tune an engine to temp but i have "ruff" temp ranges i try to stay with in. Regards Jeremy.

That's the way to do it.

I got all that I was wondering if there was a point where I should say "that's too much"