Still Confused and Have some questions...

[93Rubie]

Ok, after looking around for the threads on thermostats and reading the 160 vs 180 thread. I have not been able to determine the stock LT1 Thermostat rating...is it 195 or 180. I found what I think is a credible source and it says 180. Verification anyone???

PLEASE READ AND CONSIDURE THE FOLLOWING CAREFULLY:

My question is, if my Vette has a 180 t-stat and normally running down the road it hovers between 196-203, in town the temp goes up slowly until the fan(s) kick on at 228. With that established, how in the world would a 160 t-stat help engine temps. The t-stat determines minimum operating tempurature. With the stock stat mine is a good 15 degress above that rolling down the road with good airflow over the radiator. To me it seems the stock cooling system is only capable of cooling to 195ish rolling down the road, I could believe seeing cooler if the system capacity for exposing coolant to air (aka 2 row rad.) was in place.

It only runs cooler in trafic with the 160 or stock t-stats with a CHIP, Switch to get more air over the radiator. I'm willing to bet that the guys running 160 t-stats that say, my temps are now 10-20 degrees cooler over stock dont run them long enough to get all the coolant up to temp. Remember that the LT1 has a two way t-stat, and that if your minimum operating temp is 160 it will take longer to get enough heat built up in all the coolant to see higher temps in the normal 195-203 range.

To sum it up, any cooling system is designed to get rid of so many BTU's exeed that and the engine will overheat. Thus, system design determines max. operating temp ROLLING DOWN THE ROAD with sufficent airflow.

If the system only can cool to 195 rolling down the road and the stock t-stat is 180, what is the advantage in having a 160, besides the fact that it will take MUCH LONGER to reach 195 rolling down the road.

ANY reading for my Corvette where taken from the digital dash readout. I have used a laser thermometer to measure hose temps highest I got near water pump with cooling fans just kicked on was about 215. Kind of hard to measure head temps as exhaust and other stuff is in the way and contribute extra heat.

ANYONE MAKE ANY SENSE OF THIS OR AM I NOT CLEAR ENOUGH or OFF MY ROCKER ONE OR THE OTHER.

 

[Schrade]

Thus, system design determines max. operating temp ROLLING DOWN THE ROAD with sufficent airflow.

"Rolling down the road"? Not completely accurate.

A properly operating LT1 cooling system will lower the temps while sitting at a redlight, A/C pumping snow, 97 degrees+, from 228, when the fan trips on.

My fan cuts off when it hits 218. I think that's spec.

The 160 stat is going to open up at 160, and allow reserve coolant into the block flow, which in turn makes it take longer to warm up to the temps that it likes to burn fuel.

 

[TWISTERUP]

Stock stat for the LT1 is 180*. In order to lower operating temps the PCM will need to be programmed to run cooling fans at a lower temp.

A side benefit IMO is that if you have a auto trans you also lower trans and oil temps slightly by reprograming. This has been a ongoing debate for years on Vette forums. These cars by design run much warmer then some are comfortable with.

 

[93Rubie]

How would the cooling fans get a lower operating temperature when the car is in motion, say rolling at 45 mph down some back road. I run, as is, like I said 196-203 rolling down the road doesn't matter if it is 45 or 65, it runs those temps. If those speeds provide sufficient air flow, how would fans coming on at lets say 195 help, they would be on all the time.

I totally get them cooling in slow traffic or city driving makes perfect sense as there is insufficient airflow across radiator, otherwise.

 

[TWISTERUP]

How would the cooling fans get a lower operating temperature when the car is in motion, say rolling at 45 mph down some back road. I run, as is, like I said 196-203 rolling down the road doesn't matter if it is 45 or 65, it runs those temps. If those speeds provide sufficient air flow, how would fans coming on at lets say 195 help, they would be on all the time.

I totally get them cooling in slow traffic or city driving makes perfect sense as there is insufficient airflow across radiator, otherwise.

My '96 has stock 180* stat ..fans programmed on at 185* and I've never seen temps over 190* with or without AC...in town or highway....w/ambient temp close to 100*

The air intake on these cars is down low and picking up road heat so I'm not convinced "air flow is sufficient"....IMO it's poor. That is why I changed my programming. In a perfect world with a good clean radiator and plenty of air flow at highway speeds you could throw the fans in the trash. The nose of the C4 was designed for looks /performance and not to push air across the radiator. The fans help pull more air across the radiator...just the same as a box fan helps "pull" air thru a open window in a house. As I said before your temps are well with in specs...if you're happy---I'm happy for you. I wasn't happy with mine so I changed the programming and it worked for me!!....period

 

[93Rubie]

Hmm, you would think the Corvette Engineers would have made air flow sufficent enough to keep the engine cooler (than what it is) at speed. I guess not, if your fans keep your LT1 cooler at speed then obviously my assumption that airflow at speed is sufficent is well you know what they say about assumptions.


In my opinion anything above 200 is too hot and serves no other purpose than for emissions. The fact that my car stock runs 196-203 running down the road is enough to verify that anything much over 200* is pointless for performance.

On the other hand 160* stats with lots of fan action may keep temps cooler but my opinion is that the LT1 was designed to run a bit warmer than that. Besides if your oil doesnt get over 212 you will never burn off the condenstaton that gets in it, and that my friends is bad.


Looks like I will invest in a fan switch to keep'er a little cooler ie. below 200* but above 180.

I still can't believe that they didnt want lots of air to be shoveled through the radiator to keep the engine cooler. Some times I wonder about engineers. Another option is to do what Duntov did with the C3 big block cars, shove a bigger lip spolier on to shovel more air into that radiator.

Always, intresting...

 

[Schrade]

How would the cooling fans get a lower operating temperature when the car is in motion, say rolling at 45 mph down some back road.

Yes, the cooling fans do cool more than 'rolling'. That's the end of that story/question.

If those speeds provide sufficient air flow, ...

No, they do not. That's why the ENGINE-ers put the fans(s) where they did - because the fans cool more than 'rolling'. And that's still the end of that story.

Hope all the clouds of confusion have cleared away.

 

[vetteoz]

How would the cooling fans get a lower operating temperature when the car is in motion,

Fans cut off above 35 mph

 

[vetteboy86]

Fans cut off above 35 mph

I did not know this.

I'm having issues getting my stock booster fan to turn on. I have verified the fan works. I guess now I need to check the relay.

 

[John Robinson]

Now to the basic question of why did GM do this. Its called EPA The warmer an engine runs the cleaner the combustion process is. Now along with that they used guess what Mobil one because it had a higher break down tempurature than fossil oil. Along with all of that a 180 or 190 thermostat means that the engine on cold start up is allowed to get to operating temperature much quicker because the thermostat is closed longer. Again this reduces the emissions quicker and therefore is a part of why GM was able to sell these cars. That was not the only concession made to pass the EPA requirements. For all of you with the 2.56 gears your cars were used to average out for the performance setups. And that is all I am going to say about that.

 

[vetteoz]

I'm having issues getting my stock booster fan to turn on. I have verified the fan works. I guess now I need to check the relay.

At what temp?
The aux fan is set to start around 238F .You can replace switch in the head with one to turn fan on sooner

C4 C3 Corvette Cooling Fan Switch 1981-1995 - Mid America Motorworks

 

[vetteboy86]

At what temp?
The aux fan is set to start around 238F .You can replace switch in the head with one to turn fan on sooner

C4 C3 Corvette Cooling Fan Switch 1981-1995 - Mid America Motorworks

I'm trying to get it to come on in tuning. In the 32 mask, it was simple or so I thought. Clearly spelled out fan 1 and 2 turn on and off temps. I assumed fan 2 was the booster since 86 did not have a dual fan setup. I was unsuccessful trying to get it to come on. Possibly because the ECM doesn't control it?

I've since changed to the 6E mask, and it is looking totally different.

BTW, once you mentioned MPH and Fan operation, it stuck out like a sore thumb. I'm trying to gather information before I change it from 35.

 

[vetteoz]

I'm trying to get it to come on in tuning. I was unsuccessful trying to get it to come on. Possibly because the ECM doesn't control it?
.

'86- '89 don't have aux fan control from ECM. Is controlled by mech switch in drv side head.
Only '90 + cars have both fans controlled by the ECM

 

[vetteboy86]

Thanks for confirming!