Zef, so your saying that you'll spend hundreds of dollars modding your GTP but won't risk losing a few tenths off your mpg by going down to a 180* tstat? Weird. Also I'm pretty sure that you do have to change your PCM (or just a setting in it) to benefit from your 180* tstat.

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U-bend/ResDelete// 3.4"// MSD 8.5mm// TR6s// ZZP 1.0 PCM// 72mm TB w/ TB spacer// WizAired CAI// 180° tstat
Best ET (stock): 14.689
Best Trap (also stock): 93.82

On the highway the car will run a little cooler with a 180 on stock pcm. Because the air flow threw the radiator is enough to cool it. But in stop/go the fans will keep it at stock temp.

I'm curious to see if my gauge is right. It seems low. The ls1m should tell me I guess.

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1998 GTP , CAI box
Waiting for install: 3.4 pulley

I run a 160 and all the mods in sig @75mph I am getting around 27mpg

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PRJ Tranny W\3.29 ATI 3K stall,PRJ Wires,PRJ Fuel rails,PRJ LL Cam,PRJ Tune, Gen V,ZZP stage 2 I\C core,PRJ FMHE,Meziere I\C Pump,N* T\B,Custom CAI,TOGS Extremes,R\T DP gutted Cat,Autolite 103's,160° T-stat,Lucas 42.5#,and MPS 2.9,Hoosier QTP 12.678@110.82
http://videos.streetfire.net/video/2...Cam_155338.htm

@ 65 MPH through IL, I got 33 MPG with a 180*.

fwiw, with my fans set to match my 180, my temps stay between 186 and 175.

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04 Indy SS build #972
XP, TOG's, Lightning injectors, 2.8 pulley, 105 CC springs, Wizaired, 3.29 gears, tripleedgeperformance ported blower, machined LIM, 180* tstat, RS12YC@.053, FP rewire, Alt rewire, stage 1 V boost, PRJ wires, Stage 2 IC

What's the point of the 180* tstat though? He's right that engines are most efficient (and thus make the most power) at 195*. So, why have the 180*?

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2004 Impala LS - got some mods
NAIOA Moderator

I know for a fact I lost a 2-3 MPG on my last trip home (about 5.5 hours) due to a 180* tstat. Highway mileage has returned to normal since returning to the stock temperature.

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2004 Impala LS - got some mods
NAIOA Moderator

Use whatever works best for your car. Mine likes the 180. and based on what I've read it seems to be the optimal heat range.

http://performanceunlimited.com/cobr...hermostat.html

http://www.roadandtrack.com/article....&page_number=2

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04 Indy SS build #972
XP, TOG's, Lightning injectors, 2.8 pulley, 105 CC springs, Wizaired, 3.29 gears, tripleedgeperformance ported blower, machined LIM, 180* tstat, RS12YC@.053, FP rewire, Alt rewire, stage 1 V boost, PRJ wires, Stage 2 IC

Cooler engine normally means better performance & reduced knock.

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U-bend/ResDelete// 3.4"// MSD 8.5mm// TR6s// ZZP 1.0 PCM// 72mm TB w/ TB spacer// WizAired CAI// 180° tstat
Best ET (stock): 14.689
Best Trap (also stock): 93.82

Better performance... I question that. Reduced knock... That's what I have a tuner for.

My point is, why sacrifice efficiency in the pursuit of power if you don't have to?

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2004 Impala LS - got some mods
NAIOA Moderator

There is nothing wrong with looking for the balance between performance and efficiency.
The Road and Track take (you can find similar non Internet forum articles everywhere).

Engine-management computers rely on the as-designed coolant temperature (typically 193 degrees F) to better atomize fuel, maintain heat-exchanger efficiency, provide lower emissions, optimize fuel economy and other factors, so running the engine colder than designed can have multiple ill effects. These are the sort of effects that are not immediately apparent, so such issues are more long-term durability concerns.

Tuners often fit 180-degree F thermostats to give hot-rodded engines a larger cooling margin for when they’re making tons of heat (horsepower) at full throttle. This is a bona fide need on an engine that has sprouted a supercharger, but simply fitting a cooler thermostat to a stock engine will not lower the intake air temperature enough to matter and will not support a meaningful timing increase.

Cooler than 180-degree thermostats are not recommended on modern cars. Most domestic automakers’ engine-management systems go into open loop at 168 degrees F, meaning the engine is operating in its warm-up mode with perhaps an overly rich mixture and un-optimized ignition timing. Eventually the computer will consider such long warm-up times abnormal and could trip the Check Engine Light.

Furthermore, higher coolant temperatures promote engine efficiency, especially for fuel economy and emissions, and reduce cylinder wear (a cold block wears faster than a warm block), and the engine internal dimensions have been set for the designed operating temperature. If you’re really beating on your car in the summer and figure it’s overheating, then a 180-degree thermostat could be the answer to return your coolant temps to as-designed levels, but anything colder is counterproductive.


another related thought. If you are running an IC or going to, most rely on the radiator puller fan(s) to cool the FMHE. Typical fans settings with a 180* thermostat is 176 -182* whereas the stock fans settings with the 195* is 208 - 212*.

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04 Indy SS build #972
XP, TOG's, Lightning injectors, 2.8 pulley, 105 CC springs, Wizaired, 3.29 gears, tripleedgeperformance ported blower, machined LIM, 180* tstat, RS12YC@.053, FP rewire, Alt rewire, stage 1 V boost, PRJ wires, Stage 2 IC