removing thermostat

[sidestepkid23]

besides no heat what else is a down fall?

[AJ52486]

Your car will not reach the operating temperature that the computer expects. Since the computer uses temperature to adjust idle speed, for fuel calculations, and probably many other things, your engine won't run the way it was intended to. My truck was running very rich, and when I used my laptop to datalog it, I found that it was only hitting 143 degrees. I installed a new thermostat, and it runs much better. I've also heard that you will actually lose power due to having a cooler combustion chamber. There are many people on this site that are much more knowledgeable than I am, so hopefully someone else can explain this in further detail.

[Injuneer]

As coolant temp drops, the thermal efficiency of the engine drops = less power. The burn is not as complete, so you would lose gas mileage and emissions of HC and CO would go up. Oil would stay cooler, and not get hot enough to drive off condensables that are harmful to the engine.

In the LT1, appears the requirement for closed loop operation is a variable coolant temp, between 120-140degF (at least for the LT1). If you don't reach the threshhold required for closed loop, its going to cause a further loss of fuel mileage, and minor changes to the engine's operating conditions will not be "corrected" by the PCM's adaptive learning for A/F ratio control.

As noted above, idle speed is a function of coolant temp. Again, for the LT1 stock programming, the M6 reaches keeps the idle above 800rpm until coolant reaches 111degF, the A4 requires the coolant to reach 176degF before it settles down to 550rpm in gear and 650rpm in neutral.

The engine will take longer to warm up, and most of the engine wear occurs at cold start, so its not good to keep it too cool for too long.

[Mark B]

Good info Fred, but I thought that a cooler engine is better to a certian degree. Putting a 180* thermostat will not harm power output, it will actually do the opposite. But running no thermostat will make the engine run too cold and therefore reduce power.

[thenuge876]

Just out of curiosity why are you considering removal of the thermostat? Was just to get the engine to run colder? Was it overheating or something?

[Trash man]

why would u want to remove the t-stat? the engine makes more power the hotter it is(without melting it). u want a nice warm motor and cold air

[96Camaro]

why would u want to remove the t-stat? the engine makes more power the hotter it is(without melting it). u want a nice warm motor and cold air

I dont think so...Isnt it when the engine temp gets pretty high that it starts pulling timeing?

[Trash man]

oh yea, i yet again forget this is computer controlled cars.

[Injuneer]

What happens to power is a balance of at least three things. Taking more heat out of the combustion chamber reduces the heat that's left to produce power. Reducing coolant temps may reduce inlet air temp depending on the configuration of the intake manifold, which increases air density and increases power. Running cooler may allow more timing, increasing power IF you advance the timing as well. If you're lucky, the last two will show a larger gain than the first one will reduce power. Depends on the specific engine configuration. Obvioulsy GM felt that the "reverse flow" cooling allowed them to use the cooler coolant coming directly from the radiator to cool the heads, and allow more timing in the LT1. Interestingly, the reason they dropped reverse flow cooling on the later engines was a lawsuit from Evans Coolant, who own the patent on reverse flow cooling, and defeated GM in court - see later comment on how Evans approaches coolant operating temperature.

In many race applications, engine coolant temps are kept well above 200degF to increase thermal efficiency. Evans NPG coolant uses the increased coolant temps to increase thermal eifficiency, while controlling nucleate boiling to reduce detonation. I've got my engine running at 192degF, because that's what the engine dyno showed was best for overall power.

[Jeff_in_Atl]

Interestingly, the reason they dropped reverse flow cooling on the later engines was a lawsuit from Evans Coolant, who own the patent on reverse flow cooling, and defeated GM in court - see later comment on how Evans approaches coolant operating temperature.

In many race applications, engine coolant temps are kept well above 200degF to increase thermal efficiency. Evans NPG coolant uses the increased coolant temps to increase thermal eifficiency, while controlling nucleate boiling to reduce detonation. I've got my engine running at 192degF, because that's what the engine dyno showed was best for overall power.

I was wondering why GM dropped reverse flow cooling in the LS1. Now I know why. It's always good to learn something everyday.

[Red20170]

So their is a chance that the 160 stat and fans set lower could hurt power?

[Injuneer]

A 160 t'stat on an LT1 won't hurt power, but you need the fan on/off temperatures and the timing changed to benefit from it. It's the only part of the HPP "power programmer" that actually provides any gains. The 160 t'stat allows you to run the engine under 200degF, compared to GM's intent to provide a 210+degF operating temperature. Remember, the t'stat simply STARTS to open at 160degF, and isn't fully open until it reaches maybe 180degF. That allows the lower fan on/off temps, without causing them to run continuously.

[Red20170]

As a side note wouldn't an A4 benefit from a cooler running car?. Since the radiator fluid is cooler. The temp of the trans fluid is cooler correct?

[Mark B]

I dont know about that. The fluid in the radaitor is always being cooled. Regardless of the thermostat being open or closed. Actually, the trans fluid is probably being cooled the most when the T-Stat is closed. Because the fluid in the radiator isnt being curculated through the hot engine. It just keeps getting colder & colder from the air running through the radiator.

[DeWynter]

I dont know about that. The fluid in the radaitor is always being cooled. Regardless of the thermostat being open or closed. Actually, the trans fluid is probably being cooled the most when the T-Stat is closed. Because the fluid in the radiator isnt being curculated through the hot engine. It just keeps getting colder & colder from the air running through the radiator.

Only problem with that is, there is no circulation for any of the "hot" water from around the trany cooler. Convection may work but I doubt its very good in a rad.