mmasse

I just installed a Supercharger kit on my 993 engine. After doing some research I got the impression that it will be critical to monitor the CHT, in particular because I am not running an intercooler (for the time being). So, I installed a CHT sensor (plug ring type).

I wonder what's the normal operating range for CHT. I would like to get an idea of what should be the temp under normal driving, and also under spirited driving (as in DE events). And, clearly, what would be the STOP IT NOW, level.

So far I have only driven the car a few miles on the road after the installation of the SC and the CHT rteading is between 250-300F.

Thanks for you inputs

axl911

It depends on the cylinder and the weather.

I installed a total of 4 chts on mine. Average is about 330F normal driving at 70F. When it gets to 100F here in Texas summer, the highest cylinder ( #2 btw) will reach 390F.

mmasse

My sensor is also in cyl. number 2

Anyone with information about CHT at the track.

I am looking for what would be the temp I should consider as max for not damaging the engine

Thanks

993/907

Engines in light aircraft are quite similar to Porsche engines...flat opposed 4 or 6 cylinder, air cooled, some are turbocharged.
There are several schools regarding CHT in aircraft....I subscribe to the 380 F max school, even though the manual says 460 F; theory is aluminum will begin to soften around 400 F, cylinder barrels may deform etc, so why risk it.

Gordo

mmasse

Thanks Gordo

2Many Cars

I'm not sure the intercooler (or lack thereof) makes your CHT higher. If anything I think you could argue the denser charge with the intercooler might even make the CHTs a tad higher. Can't imagine it's a big difference either way as far as CHT is concerned but others here may have hard data to prove otherwise.

Sorry if I'm taking this thread a bit OT.

Juha G

I think you need to be more worried about detonation than cylinder head temps when running without an intercooler.

The hotter the intake air temp, the bigger the chance of detonation.
So watch your IATs...

axl911

Mine is a daily street driver, and I don't a notice much increasing in cht when driving normally. Maybe constantly in boost would be different. But by the time you have high enough to melt the head, your engine would have been long gone from detonation, etc.

Juha G

Here's some info about the CHT range: https://rennlist.com/forums/9267104-post132.html

mmasse

Juha,

excuse my ignorance, but what does "IATs" mean?

Thanks

trophy

IAT is Intake Air Temperature, the ECU uses this to adjust its mapping.

mmasse

How can I monitor the IAT? Can i piggyback on the ECU signal and connect a gauge? Or do I need an extra sensor?
Thanks

trophy

You can pull off the sensor or the input into the ECU, for 55pin ECU it is pin 47, can't remember what pin for the 88 pin ecu.

axl911

That prob won't give what you're looking for since it is pre-supercharger.

AIT should be done after the air is supercharged and through the intercooler.