Thermostat poll, 160 vs 180

[jcs44]

One of the gear heads needs to answer this one. I'm not positive, but I believe the whole cooling system on later C4's with the LT1 or LT4 is a different set-up and tends to run hotter. Yours seems to be running pretty cool, however. I doubt that the 160 would do anything for you. It really doesn't do anything for an LT1 or LT4 either unless the fans are reprogrammed to a lower temp.

JCS44
LT4 Vert, Triple Black

 

[tigmaned]

used a fulke reader and my gauge is right, on cooler days only running at 175. i pointed it at the stat housing, 165. just below the stat housing, or should i say the intake manifold 185. upper hose 144. lower hose 95. exhaust manifolds over 500! hee. intake runners 120. yeah i was having fun with the laser!! i have noticed when my vette is just a little warm the fans are always on. could it be keeping the engine to cool? all this with a new rad, and 195 stat. i mean combustion engines need some heat to them. when i failed my emissions test it was around 180.

 

[WhalePirot]

I’ve been watching this thread since it started. The thermostat is NOT a switch, it is a valve and throttles the flow of water to the radiator. Under normal operating conditions the thermostat is neither closed or full open, it will be controlling the temperature near its design temperature.

I have also read this thread since the start and I cannot believe this is still being discussed.

This would be news to the cooling experts I talked with at FlowCool, the supplier of the performance water pump I run; the folks in California, mid-coast. In a nutshell, the thermostat is a valve that opens at the design temperature, to keep the coolant in the engine long enough to absorb the excess heat and in the radiator long ehough to dissipate that heat. Essentially, is acts more like a switch than a partial-flow valve, in constant open/close action. Their description; not mine. Are we talking semantics, here?

I will check for the expert article I recently read on why 180 should be lowest thermostat choice on these engines.

 

[bobder41]

180 with ?

I would like to run a 180 stat in my 90 L98. I belive to 160 is too low for normal hwy driving. I am running a 195 now I am trying to find someone that program the chip to have the main fan t-on at out 210 instead of the 230 temp the factory has set. If anyone can supply me with a source to find a chip set up for the 180 stat and fan mod. I would be appreciated Bob

 

[The Corvette Kid]

I ran a 180deg hi-flow unit for a couple of years, but switched to a 160deg hi-flow this past summer. Other than lower temperatures while cruising on the highways, I didn't notice any difference in performance between the two. The temps do rise a little slower above 160deg than before though.

I've read an article on the net that says 160 is actually too low, and will result in high engine wear over time (in fact, the wear as a result of running a 160deg is TWICE as high as running a 180deg); a 180deg tstat is the best compromise between the high temperature stock unit (which is the best choice for emissions compliance) and performance enhancing low temperature units.

I'll probably switch back to the 180deg before next spring (the car is going back into storage the end of October), but I want to have the PROM reprogrammed to turn the fans on earlier. That will offer the greatest gains with respect to keeping the car cool.

 

[Louis Bartay]

I am sure it depends where you live and do you drive in stop and go traffic. Ft. Worth Texas gets Really hot in the summer so for the last five years I use a 160, BUT I Reprogrammed the computer (Hyper-Tech) so the LT4 still passes state inspection (smog test the reason GM runs them hot) my fans turn on sooner and I clean the radiator evey few months with my air compressor ( lower the PSI so you do not bend the fins) I am always schocked at how many leaves and trash finds it way in front and behind the radiator.

 

[landpilot]

My old C4 runs anywhere from 160 to 192 with a 160 degree thermostat. It had this in it when I got the car a little over 2 years ago. I can see how a 180 or 190 degree thermostat would cause the engine to warm up sooner, but I disagree on the thermoshock theory. There's water in the system and starting to circulate it sooner would have the reverse affect of shock.

Oh, BTW I do drive it year round here in Dallas.

 

[Louis Bartay]

Hey landpilot

I have been reading page after page and most of the owners are Not reprogramming the computers, and the LT1/LT4 has reverse coolling. Meaning the water goes to the head first GM started this with the LT1 in 92 I think where as the older C4's were like the old small blocks. If those guys drove on 635 during rush hour they would runa 160 AND reprogram the computer so the fans turn on sooner and stay on longer and the engine timeing ,etc is altered for the cooler temp. My LT4 runs much cooler now and runs faster, no way I would un do the mod's I have done. I forgot to add I have moved the MAF sensor from the bellows in front of the throttle body to the air filter box so the computer reads a cooler temp and does not retard the spark advance.

 

[code5coupe]

I'm not sure I get this thermo shock thing!!!

I don't quite buy it either....
I work in heat treating of metals (among other things) and in the world of metallurgy, there is no such thing as "thermal shock". That's a term that has been devised and used by laymen, not metallurgists.
The sole purpose of a thermostat is to decrease warm-up time. It doesn't control running temps...unless it's a 230degree 'stat!
Larry

 

[hwfcpa]

160 degree thermostat

I have a 93 LT1 with auto trans. I run the 160 degree thermostat with a hypertech chip which is programmed for the 160. I've had no problems. The car runs cooler in the summer. I only drive it ocassionaly in the winter, but the car heats up and provides adequate heating for the occupants. My undersatnding was that the only thing that might suffer was the pollution control, which is supposed to be better at highr temperatures.

 

[Louis Bartay]

I have a 93 LT1 with auto trans. I run the 160 degree thermostat with a hypertech chip which is programmed for the 160. I've had no problems. The car runs cooler in the summer. I only drive it ocassionaly in the winter, but the car heats up and provides adequate heating for the occupants. My undersatnding was that the only thing that might suffer was the pollution control, which is supposed to be better at highr temperatures.

Trust me you will pass smog tests with no problem( if your engine is still in good shape). Hyper-Tech did their R&D on this and my Vette LT4 and my wifes LT1 94 Bird both pass the smog test and the Bird has 149,000 miles. For total HP gains Kenny Brown or some other good tuners that use a dyno and make custom maps for your Vette with what ever mod's if any that you have done. But taking your Vette to a shop with a Dyno is expensive but the air/fuel ratio will be spot on for where you drive. Hyper-Tech gets really close so let us know when you have your vette inspected.
Merry Christmas
Louis

 

[trinitystudio]

I have recently put a 160 and a new radiator in my 84. In So TX it used to run 220-230 with a/c i the summer. It was 65 today and the car ran 165 while moving but would climb to 210 while caught in traffic (no /ac). I haven't changed the prom yet but that's coming. I was surprised it got so hot sitting on the cool day. The fan never turned on as that usually comes at 220.

 

[Louis Bartay]

Jim
My point on the reprogramming of the computer. Hyper-Tech makes a part for your year model that will turn the fans On sooner. Also the performance prom will make your engine pass state inspection now that you have a 160 stat. Happy Holidays
Louis

 

[douglas foster]

father & son

just replaced with 180 , but i really feel that cleaning out the front of your radiator makes the real difference. also added a front inlet grill, from Ecklers.

 

[Louis Bartay]

just replaced with 180 , but i really feel that cleaning out the front of your radiator makes the real difference.

It does, as does cleaning Behind it, you have to remove it(radiator), and I am always suprised at how much crud gets vacuumed up in there. But the 160 and reprogramming (the fans turn on at 170) Really was a bigger difference in stop and go traffic with a/c on for a hour driving home from work in the summer when it is 105 degrees out side.The LT4 has a higher lift cam and tends to runs a bit hotter than a stock LT1.
Happy Holidays
Louis

 

[speedmaster4]

in the old days--B.C. (before computers) everybody ran 160/summer and 180/winter, and everything ran great...then along came "emission controls" with 195 t-stats....helped fool the feds test but cam lobe wear/warranty costs became a big problem...roller cams were a high cost band-aid for lubrication problem

so we're all cool with our 'garlits' roller cams,but what about everything else in the engine that depends on oil lubricant/cooling...gimme the good ole days

dammit, the o/d on my 4+3 doesn't work rite @ 160, 180 is ok....seen graphs that say 180 is best for wear, maybe the graphs aren't lies, so 180 is ok...ran jet boats that cooled with lake water and picked up maybe 100 rpm on top end by restricting flow, so 180 is ok...dont see 'white crud' on underside of oil cap with 180 but do see a little with 160, so 180 is ok

right???

 

[Louis Bartay]

in the old days--B.C. (before computers) everybody ran 160/summer and 180/winter, and everything ran great...then along came "emission controls" with 195 t-stats....helped fool the feds test but cam lobe wear/warranty costs became a big problem...roller cams were a high cost band-aid for lubrication problem

so we're all cool with our 'garlits' roller cams,but what about everything else in the engine that depends on oil lubricant/cooling...gimme the good ole days

dammit, the o/d on my 4+3 doesn't work rite @ 160, 180 is ok....seen graphs that say 180 is best for wear, maybe the graphs aren't lies, so 180 is ok...ran jet boats that cooled with lake water and picked up maybe 100 rpm on top end by restricting flow, so 180 is ok...dont see 'white crud' on underside of oil cap with 180 but do see a little with 160, so 180 is ok

right???

Do you have a Hyper-Tech Prom for your Vette as it also tells the fans to turn on sooner and it improves HP by increased timeing etc, so if you have the HP Prom try a 160 and see what the trans does then.

 

[grumpyvette]

after reading thru this thread I find some important points have been TOTALLY ignored, and thats the fact that the engines coolant temp effects or at least tends to effect the engines OIL TEMP. and its a flat out proven FACT that oil temps in an engine that fail to at least slightly EXCEED 215 F durring engine operation for several minutes tend to hold moisture and create ACIDS from the combustion bye-products trapped in the oil mixed with that moisture, those acids can and do cause problems if the engine sits without running for awhile.
then theres the fact that widely varing engine temps. tend to make tunning more difficult also., if your engines temp swings from 160F-235F theres no way the engines going to run as smooth and efficiently as one that tends to stay in a far more limited range of lets assume 190F-210F on the coolant like MY corvettes been designed to do .the fans come on at 210F and I run a 195F t-stat
short answer, Id sellect the 180F or 190F or even a 195F as a far more reasonable choice than the 160F T-stat and Id sure pay more attention to keeping the average OIL temp in the 215F-245F range than the COOLANT TEMP! under 180F

REMEMBER THAT CHART???

WELL ALOT of that PERFORMANCE ADVANTAGE and engine wear are effected by the operating temp of the OIL and its ability to clean.lubracate and transfer absorbed engine HEAT to the coolant, and the oil won,t do its most effective work untill its up to a minimum of 215F and its film strength tends to break down (depends on type of oil) between 250F-280F over time, so youll want to change oil more frequently if the oil temp tends to run out of the IDEAL range of 215F-245F

you may also want to keep in mind that CAREFULLY CONTROLLED HEAT in the combustion chamber tends to make more POWER, thats why IRON cylinder heads if identical to aluminum heads will tend to make a couple more hp with IDENTICAL compression ratios,(they tend to hold heat in the combustion chamber longer)thats also why you tend to get detonation quicker with iron heads
fuel droplets carried in the airflow thru the ports hitting hot valves and combustion chamber surfaces tend to vaporize, but the time being in micro seconds this favors the hotter chamber with more tumble and swirl, cooler temps tend to slow the burn time reducing power

 

[speedmaster4]

actually i do have a hypertech chip...kinda surprised me that the o/d wasnt happy with it and 160 stat...o/d is fine with 180 now

also didnt know secondary fan in front of rad was not ecm controlled until i got service manual...toggle switch in parallel with cyl head sensor switch now

 

[Louis Bartay]

actually i do have a hypertech chip...kinda surprised me that the o/d wasnt happy with it and 160 stat...o/d is fine with 180 now

also didnt know secondary fan in front of rad was not ecm controlled until i got service manual...toggle switch in parallel with cyl head sensor switch now

I noticed you are in NY is this a winter or summer problem?

Grumpyvette,

You are on the mark about your oil temp, but here in Texas with 105 degree summers my oil temp after warm up stays above 215 and I change Mobile One 5/30 every 3,000 miles(LT4), and I have 70,000 trouble free miles. I can open the oil filler cap on the valve cover and the aluminum still has the orginal color ( no brown discoloration) before I reprogrammed the computer and 160 stat my cooliant would go 250 and oil 300 in stop and go traffic ( got tired of turning off a/c) now 210/220 worst cooliant and oil 220/235 100 degree stop and go traffic back and forth to work(90 minute drive each way) every day. This is with GM 50/50 mix cooliant/antifreeze. I usually pull the radiator every second spring and clean out the crud that gets trapped in between. And I clean out in Front of the radiator once a month as my Vette is my daily driver.A C4 is rolling vacuum cleaner, I hate people that mow their yards and leave the cuttings in the street.