The Truth About Running Colder Thermostats
 

So what's the deal. As usual, there seems to be two schools of thought.

1 - Especially for "high" performance engines, that is higher compression or forced induction, lower temp thermostats are "good" and "helpful". Run a colder thermostat than stock

2- That's horse shit. Engines are designed to run optimally in an operating temp range, arbitrarily forcing the temp down is not useful. Run a stock thermostat regardless.


FTR, I have a moderately high compression engine, somewhere north of 11:1. I'm currently running a stock stat, which I think is 190. Would I get any benefit in any context from running a colder stat?

I have 160 degree thermostat in the Goat and I think it runs much smoother than before.

Cooler is better. Just make sure the computer is set to use the cooler temp. If you don't it'll look for the 190 temp and not find it.

Cold air and fuel make more power.

Ok, before someone else states it---engines make more power at 200 to 220 degrees. But, that is a racing engine. What you need is to have enough temp to get the oil up to about 180 to 200 degrees so that all the water vapor is steamed out.:boggled:

nuff said:hail:

If your wondering, the car will run richer at a cooler temp than what the ECM is tuned for thinking the car hasn't reached operating temp.

Isn't the oil typically 20 behind the coolant? So wouldn't you want a minimum of a 200 degree tstat?

Brutal got it right for the most part. Decreasing the charge air temperature increase the air density therefore more O2 make it into the motor.

I like running lower temps simply because it helps with longevity of the motor.

Race engines do like to run hotter, but many times thats a materials issue. The comp cams spring that many lsx guys run are significantly stiffer than stock. The result is that they can become brittle when cool. As a data point my car runs 205-210 on the track and oil temps get ~255-270.

As far as the car running rich when cool, I don't really see that as an issue since most modern cars have charge air temperature as one of the variables they monitor.

Do you run a MAF tune or Speed Density? I was considering switching over to Speed Density. . .

Nope, MAF and I would recommend staying with it. Who did the tune on your car?

Z-Industries
http://www.z-industries.com/

The tune I'm running was done on and ostensibly for 91 Octane (it included mods to the computer not to through codes for my swap which doesn't have things the F-Body does.)

It will run in the winter on winter blend 91 acceptably well, but not in summer, it'll ping. It's also EXTREMELY mild tune, something like 18 degrees total. The motor supposedly was "only" 11.1:1 or so, but it must be higher than that not to be tunable for 91. The previous owner ran an agressive tune on 50/50 race/stree gas. He had headers and an LS1 intake and I have stock manifolds and an LS6 intake. He made about 430WHP in his C5 and I make about 390 in my C3.

You ever think of running Torco?