I'll quote Chris Petris in the Nov 05 issue of Corvette Fever: "Performance PROMs are necessary when major engine modifications are made. Installing a performance PROM along with a 160 degree thermostat when your engine is stock makes more power bacause the engine runs in "open loop" most of the time, causing poor fuel mileage and accelerated engine wear. During "open loop" the computer provides a fixed air/fuel ratio that's richer that normal to improve cold driveability until the engine warms up. Also, the cylinder walls are constantly being washed of lubrication from the excessive fuel in the combustion chamber, possibly adding damage to the engine if the condition persists.
Keeping the engine coollant at 200 degrees keeps engine wear to a minimum and raises fuel mileage. Cool intake air for all-around power and engine performance is the most important thing."
This seems to go against conventional wisdom and advertising hype.
Anu thoughts?

 

Though some here will argue that 160deg promotes engine wear, for sure the ECM will go closed loop and stay there just as quickly as with the conventional T-stat.

 

The engine does not run in open loop most of the time, and goes into closed loop and stays there just like any other thermostat.

People who say that don't understand or know the parameters for closed loop operation in our engines.

The 160 works for L98s, powerwise, because it slows heat soak of the intake, which preheats your intake charge, so you'll run quicker times when the engine is cold.

 

It's also a good idea to move the intake temp sensor in front of the MAF, (101 Project for Your Corvette)

 

Engine wear increases with decreasing operating temperature. Engine companies have proven it by actual experiment and the same is claimed by lubricating oil companies. This information has been posted in the past in C4 tech but may be too old to find in the archives. Installing a 160 deg thermostat does not ensure 160 degree coolant temperatures and it also does not insure increased hp claimed by many CFers. Several members have swapped thermostats during dyno time and found no increase in hp with a 160 deg thermostat installed and posted their findings here. Engine manufacturers also state that hp decreases with decreasing engine temperature.
The only claim I have ever read from CFers about why 160 stats cause an increase in hp is that induction air isn't warmed as much as higher temp stats allow and the charge density is higher. I agree that this much of their thinking is correct, what they do not understand is that there are other engine effects from an actual 160 deg coolant temp that is the cause of a decrease in hp, mainly the decrease in thermal efficiency by the transfer of heat from combustion into the coolant and the resultant decrease in BMEP causing lower hp. Also, lower temp lubricating oil causes an increase in friction which robs the engine of hp.
I don't ever expect the discussion of the effects of a 160 degree thermostat to end but the proponents of 160 stats appear to me to refuse to believe engine manufacturers and oil companies. I don't know why.

 

http://www.carnut.com/ramblin/_cool3.html

180-200* coolant is the ideal operating temp when considering the power vs. engine wear (and it stands to say oil would be about 200-220*)

The above link supports the idea of going with 180* (L98) and sticking with 180* (LT1).

By the way, if an off-the-shelf commercial chip is being considered with major mods, its the absolute WORST idea. A true "custom" chip by a tuner, after working with YOUR car, will maximize performance for YOUR car, and it will be recalibrated according to the operating characteristics of YOUR car.

 

Remeber 2 different animals guys.. LT1 and traditional SB. The real important factor is oil temps and just because one thermostat works well in the other does not mean that it will work in the other.

Oil temps are higher than expectedin the LT1 because of the reverse flowign coolant system. This is why they come factory with a 180 degree themostat.

 

That does nothing for a MAF car, the Intake air sensor on a MAF car is mostly just used for EGR functionality.

 

There are other things to consider when lowering coolant temps. Such as the minimum temp to allow highway fueling mode...185+, minimum temp to allow TC lock up 120 (getting close to that 160) minimum temp for cannister purge 140.
There are more things dependant on coolant temp than just closed loop (112*).

 

Morley and/or Alvin, can you elaborate a bit on this? For instance, I have my fans set where cruising on highway settles in at 83-85*C (181.4-185*F), so I'm right on the cusp of what you're referring to. Am I running too cool? Its my feeling that while on the low side of the "cool" range I'm right where I want to be......Thx

 

Don't worry about a low temp stat effecting either closed loop or TCC lockup.

I run a 160deg T-stat year around and drive the car in winter and have no issues with either function.

BTW, last Christmas I cruized back from OH and pulled over 31mpg highway, so my T-stat isn't hurting closed loop operation.