I would think it would be better to run your car at a constant low temp. With my setup(160 stat, manual fan) i stay at 180 all the time. With stock setup, its at about 200 and goes back and forth to the redline.

 

"quote"MrBigXL-- from what i heard, the higher operating temp is purely for emissions. higher temp = more complete combustion

but lower temp = more power (maybe a little)
exactly right! You can honestly say that your car doest run better when its cold? EVERY car i've ever had did, and I've had several(old timer here). Thats why they make "cold air intakes", cold air?? I know my 160 stat and programming was "one" of the best things i did to my ride, I love seeing the temp gage around 170-180 with the air kicking and 90 plus temps outside. Heat can kill a motor, trust me. The motor does need to be at least 160 i would say to play it safe. Why do peeps make manual fan switches? to get the motor cool? hummmmmm...........

 

Umm. Wouldn't more complete combustion = more power.


I think what a lot of people confuse is engine temp, and intake temp. With some cars you may lose power with warmer coolant temps , BUT that is most likely because of timing being retarded by the computer as the engine temperature rises. And maybe because of engine heat radiating to the intake manifold, which would,or could heat up the intake charge. Not because a cooler engine coolant temp makes more power. Cooler INTAKE temps make more power. Not saying you can always do so, BUT if you could control for these things ( timing retard and keeping the intake cool) a warmer engine coolant temp, would probably make more power because of the more complete , efficient combustion. Now I know you can't solve these two things all the time, but I'm just stating this, as it seems that many seem to think that a cooler block makes more power .

A warmer engine temperature would like you said make more complete combustion, which should make more power IF THE OTHER THINGS ARE ACCOUNTED FOR , "which they often are not" When power drops because of the engine temp, it's most likely not because a cooler block/coolant temp makes more power...... It's most likely because of other things.(radiant heat to the intake, timing retard)
Because again, a warmer block temp UP TO A CERTAIN POINT should make more power because of the more complete combustion.

The ideal would seem to be, A nice warm block/coolant temp (TO A POINT), with a COOL intake temperature, and a computer programed to keep the timing from droping at certain engine temps.

Maybe the experts could chime in.

 

I think the biggest thing here is the fact that you can run more timing with a cooler engine(heads) without detonation. Our car has even more of an advantage with its aluminum heads and reverse cooling system. Sounds to me like GM wanted to keep the heads cool for some reason. The reason power programmers suggest you go to a cooler thermostat is because they are messing with the advance. That being said, I am putting my 12:1 383 in this weekend and I am using a 160 stat and water wetter. The way I see it is if I am going to drive my car everyday in phoenix with temps reaching 120, I am going to need all the help I can get to keep her cool and detonation free.

 

To pass smog. No econo box needs to run so hot and they do not.

 

Because sending unburnt fuel out the pipe = smog.

 

Put a Griffin in mine about 3 1/2 years ago. It was about $500-550. Car never overheats. During the hot summers in Mohave Desert (DEATH VALLEY CA 120- 130), my car never came close to overheating. In any case if your car is basically stock, just get a low temp stat, and water wetter and you will be fine, I would also look at changing all the hoses if you have the same ones that came from the factory, hoses will start to "balloon" when they get old (restricting coolent)and you may not see it untill the hose finally breaks. In any case good luck.

 

I originally thought that too,
but then i thought- that thing is on the sniffer for 30 seconds after sitting for 15 -20 min. how is that helping anything?

Also, after some research if found that the wear rates of the metals were THREE TIMES AS HIGH with a 160 stat.

 

that might just be the sillyest thing i've read in a good while.



mycarisfasterthanyours -

running 20* colder coolant probobly isn't going to make or break you. I just hope you have chosen a cam that will bleed off a lot of compression. Arizona uses 91 octane right? no 92/93? or have I mixed it up with some other state?

either way. small cam + 120* + 12:1 compression and you might start to see some issues.

 

What "metals" are we talking about here?

What was silly about rpm280's post?

Ryan

 

This thread is interesting. Anyone else have any input.

Fred?? I would like to hear from him.

 

Rings or block, i want to say rings... but not 100% sure. I read this a while back, maybe a year ago or so.

I dont think our PCM retarts timing in relation to coolant temp

and coolant doesn't run through the LT1 intake

 

I think if you check, you will find that both performance cars and econo-boxes have gone to higher coolant temps over the years. I believe most conventional flow cooling engines come with 195degF t'stats now. The LT1's 180degF stat is an exception, because of the reverse flow cooling.

Why would manufacturers raise the coolant temps:

-reduced emissions. Higher temps reduce emissions of HC's and CO. Unfortunately, higher temps INCREASE the formation of NOx. That's why they recirculate exhaust gasses through the EGR system under moderate load/low rpm conditions that cause high combustion chamber temps. To COOL the combustion (Trey - you're dangerous when you get into some of these tech topics ). The relatively "inert" exhaust gasses displace oxygen, and reduce the amount of fuel that needs to be burned, resulting in cooler combustion temps.

-increased fuel economy. If you burn the HC's instead of dumping them out the exhaust pipe, you get the energy that is released by the combustion. Less fuel to generate the same amount of energy.

-increased thermal efficiency/power. Whoaaaa.... what did he say? YES, increasing the coolant temp means that LESS heat is removed from the combustion chambers. More heat is left in the combustion chambers, causing higher cylinder pressures, and more power to be produced. Wait a minute - contradicts the whole idea that lower coolant temps makes more power..... see below.

The engine is designed, as Trey points out, to operate at the 220degF coolant temps that everyone sees in a stock system. It isn't hurting anything. The risky area is the oil.... too many excursions of the temp over 230-250degF and the oil will start to burn. Here is where synthetics help a lot, because they can stand up to elevated temps better, withyout breaking down - but that's a side issue.

So...... why do we lower the coolant temp on the LT1 and "maybe" make more power.

-You can run more timing. I think this is all the HPP+ does when you select the lower fan on/off temps with the 160degF 'stat. I've seen dyno tests that pretty much prove that the ONLY power the HPP+ can add is due to the 160degF stat. Of course if you don't advance the timing, you won't gain this HP. You will have lost HP due to reduced thermal efficiency.

-although there is no coolant in the intake manifold, it does flow through the throttle body (at least in a stocker) and it does keep heat in the heads, which flows quite well into the aluminum intake manifold, and heats the air flowing through the intake. Appears that there is some gain from the reduced intake air temps that offset the loss in thermal efficiency.

I have never seen any practical evidence of unusual metal "wear" due to the 160degF t'stat. I know I ran one in my bolt-on engine for about 50K miles with no problems... the engine, bearings, cam, pistons, cylinder walls, etc. were like new when I pulled it apart at 65K miles. I still run the same old 160degF t'stat in my stroker, with the coolant set to hold 195degF. That temp was chosen based on the engine dyno tuning. So.... running at 165degF isn't necessarily the best point. It can only be arrived at with fairly extensive tuning of timing, coolant temp, A/F ratio, etc.

As far as retarding timing... I honestly don't know what the stock PCM does, because I don't use it, but I definitely have timing offset tables programmed into my MoTeC to pull timing based on coolant temp and inler air temp. Perfectly logical.

 

well i don't often like to assume i have as much knowledge as alot of you... but just for the sake of argument i'll throw my ideas out there...

I don't believe that the block being 20 degress cooler/warmer is going to affect the amount of combustion... its a proven fact that a cooler/denser intake charge provides more power... all performace modifications and parts created to allow a cool intake charge are designed to keep in the intake charge as cool as possible... (like keeping the air away from engine heat effieciently) now that air, that we spent all the time trying to keep cool is what is combusting... allong with fuel obviously... so if what your trying to explode is best at its coolest i do not believe there is a difference between engine temp... and intake temp as far as performance goes

now i think its quite possible that gm wanted to engines to run a little hotter for emissions NOT FOR A MORE COMPLETE COMBUSTION.... but an overall higher temperature of exhuast gases.... as we all know cat's don't work until they are up to temperature... which is why i can smell my car running slightly rich when i start it up on these cold new england winter mornings... the hotter the cat = the better the cat works (to a degree, obviously)

my .02

 

Fred-
this is where i'm lost...

I knew the EGR cooled so with that same logic i said hey, why would they INCREASE coolant temps only to decrease them with the EGR?
Isn't this like like pumping up the a/c and then starting a fire in the fireplace sayng the two will balance each other out