Engine Temp Vs. Performance

chuckr · 11-21-2005, 05:46 AM

I am just wondering about a 3.2 motor and the
running temp. Does a cold engine have an effect
on the performance ? mine tends to always
be on the cold side of the gauge. It takes an
hour at idle just to get the thermostat to open.
My temp gauge never gets above the middle
I have never had my cooling fan come on.
My old SC always ran at middle postiion or
above, I had a front cooler w/fan, that helped
but it still ran at or around the middle of the gauge.
I am new to the 3.2.... is this normal ??
I live in Louisiana and it gets pretty hot in the
summer and it does not get very cold in the
winter. Yesterday it was in the high 60's
My car runs great, idle's fine gets good mileage
I'm just curious about the temp.
Thanks,
Chuck

The Donkey · 11-21-2005, 06:11 AM

I am curious about this as well. I just got my 85 Carrera and when at operating temp it runs at the 1st Bar. When in traffic in 70 degree heat, stop and go traffice I did get a bit worried because it creeped up close to the red zone. I don't remember a fan ever coming on. Is it supposed to?

It takes about 15 minutes to get it up to temp in 60-70 degree weather.

masraum · 11-21-2005, 06:32 AM

The fan on a 3.2L car doesn't come on until 245*F which is the last white mark before the red. If you got to the red and your fan didn't come on then something may be wrong.

Chuckr, sounds like you have an unusually cool running engine. I doubt that there's anything wrong with it, but you should offer up some prayers of thanks to the Porsche gods for this good luck.

masraum · 11-21-2005, 06:36 AM

Oh, and to answer your question, generally lower temps help performance.

chuckr · 11-21-2005, 06:38 AM

another reason I was asking is the oil (Redline 20/50)
I use says it need a certain temp to work

From Redline....
The ultimate high-temperature protection in Red Line engine oils recommended for street use. Good for engines that regularly run very high oil temperatures. Best for engines that run large clearances such as air-cooled engines or large-displacement, all-out racing engines that see occasional street use. Provides 25% more viscosity in bearings than petroleum 20W-50s. Not recommended for use in cold climates where temperatures are at or below 10°F or -12°C. Not recommended for street use in production engines that see sustained oil temperatures below 225°F (those engines should use Red Line 10W-30 or 10W-40).

I do not have the numerical gauge... does my 3.2 run in these temps ?
thanks,
Chuck

The Donkey · 11-21-2005, 06:53 AM

I think that the car was right at the last mark. it did not go into the red, but the last mark is quite close to the red zone. it was when i picked it up and driving back 450 miles. So, i didn't know the car and was panicking quite a bit on the NJ turnpike.

wolf · 11-21-2005, 07:10 AM

85 has got no fan for the frontcooler, came in 86 or 87...

svandamme · svandamme's Garage

Quote:

Originally posted by chuckr
It takes an
hour at idle just to get the thermostat to open.
My temp gauge never gets above the middle

Chuck

idling is not a good way to warm up your engine, you need to drive it as soon as it settles down after starting it up... 30 secs, to a minute then drive it...keep the revs low-ish untill it warms up then gradually drive it harder as it warms up to operating temp...

Quote:

Originally posted by masraum
Oh, and to answer your question, generally lower temps help performance.

i always understood that higher temps are better for performance, yet worse for longevity...

unless you're talking the temp of the air at intake... but that doesn't related to this thread.

EDIT, with hot i mean , for ultimate performance, the engine should be designed to run as hot as possible, within the required lifespan of all the components... eg, F1 engines , only designed to last xx hours, run extremely hot, but churn out immense power.. while , normal streetl cars are designed to run a lot cooler, so they live longer, and as a result they get a lot less power per liter displacement compared to F1 or other race-specific designed platforms... off course other factors do contribute... but i did understand that the rule was , for performance... the hotter the closer to ideal....

dd74 · 11-21-2005, 07:51 AM

Quote:

Originally posted by svandamme
i always understood that higher temps are better for performance, yet worse for longevity...

This is what I've heard as well...

KCPSG · KCPSG's Garage

As Masraum says "thank the Porsche Gods"
I agree, however I do live a bit further south than you the temps aren't that much different. I however did see higher temps than you are reporting, (FYI just above the bottom block is 140* and the next hatch mark is 194*, the next is 248* and just below red is 302*) my thermostat was opening up somewhere around 200* and the fan was coming on around the 248* mark...I ended up installing a lower temp thermo fan switch into the fender oil cooler and now see much,much lower temps.
I also jest recently ( because of another slight gauge problem) ended up disconnecting all of my ground leads and cleaning them and re-connecting them, and found that my temp gauge reads even lower than before....go figure

livi · 11-21-2005, 11:17 AM

Mine never passes the first thin white line and it usually takes at least 20 minutes to reach it.

But then a Carrera is a very cool car !

masraum · 11-21-2005, 11:22 AM

My '88 would get hot in traffic if I had to sit for long periods while idling, but on the move mine usually stayed right around the first thin white mark or just above so it probably ran 200-220.

klaucke · 11-21-2005, 11:35 AM

Speaking thermodynamically, if we could have the motors operate at higher temperatures they could be more efficient. The maximum possible efficiency of an engine is e=1-Tc/Th, where Tc = cold temperature and Th = hot temperature, and e=1 would be 100% efficiency.

However, with our internal combustion engines you have to realize parts are made to run within limits, and that the intake air can be heated and hurt the volumetric efficiency of the motor. And just because you have better efficiency energy wise, does NOT mean that you are making good specific output i.e. HP per liter. So a 2.2S motor may have a very high hp/liter, in reality may be very inefficient in the use of it's fuel.

Engine longevity is directly correllated to the operating temperature, and cooler is better once you reach proper operating temp. Someone even posted a graph of engine life vs. operating temp, and it looked like an asymptote or inverse function. Not to mention better/proper oil pressure while the engine is running cool.