A question to the group...


I just had my 2004 mn6 vert tuned, and I'm very happy with the result. In the process, the tuner changed the stock thermostat to a cooler one, I think 160F. In the most recent Corvette Magazine, Tech Nerd talks about why changing the stock thermostat is not such a good idea.

So the question is, what are the pro's and cons of the stock vs cooler thermostat in a tuned mn6 LS1?

Thanks, and let the debate begin!!

 

You know that you also have to re-program your radiator fans to make the most of a lower thermostat.

Cons are:
1) if you don't get over 212 dgrees F, you won't "burn off" water contaimination in oil, causing poor lubrication and extra wear.

2) Tolorances of engine parts are made to operate at "normal" temperature, aluminum expands greatly, you will be operating at non-designed temperatures, could cause more friction, wear and less horsepower.

3) Engine computer may enrich fuel mixture, causing more horsepower, but excess fuel could wash off oil causing more wear and oil contaimination.

4) You will increase emissions.

As you can see, I am not a fan of reducing thermostat temperatures.

 

John,

About 18 months ago I made the following changes:

1) Installed Ron Davis Racing radiator, with integrated oil cooler

2) Installed 172 degree F thermostat

3) Reprogrammed both fans to come on at 189 degrees F.

Results

My water runs consistently at 185 to 187 degrees F.

My oil runs from 185 to 199 degrees F.


I had Blackstone Labs evaluate an oil sample after I had made those changes because they were some "armchair experts" who said I would have water in my oil because I never exceeded 212 degrees F.

Blackstone's test report said there was ZERO water in the oil, the oil was in fantastic shape after 3,800+ miles (Mobil 1 0W40), and there was no sign of wear or contaminants in the oil.

I would suggest that you replace the 160 degree thermostat your tuner put in with a 172 degree stat.

Good luck with your decision.


.

 

Well, you got one right anyway. The LS1 was delivered by GM operating at higher than optimum (for HP) temps to reduce NOx emissions. Mine, with a 160 for the last 5 years still allways passes the sniffer test.

You don't need to run the engine above 212 water temp to remove contaminants from the oil. Make a spirited run now and then and the oil temp will be high enough to take care of that for you.

The PCM goes out of cold loop (enrichment) with a temp in the 120's so, 160, 172, 195 stat, doesn't matter.

Tolerances are not a problem with this small change in operating temps. The PCM allows full power operation at much lower temps than these. Pistons have allways been aluminum alloy, with no problems at these temps, the cylinders are steel lined, blocks and heads have been cast in aluminum for the last what, 70 years? No problems with tolerances have developed.

What this change WILL get you is a reduction in KR, and an opportunity for the tuner to get more HP with timing changes.

 

Excellent write up!

I can't tell you how many people say "higher temps for performance" its about emissions not power...and I like you I get nervous in my C5 (before Stat change) when it gets up to 235* in stop and go traffic...that is NOT good long term! in fact, it will break down oils faster...I was involved in mechanical engineering many years ago when the airlines adopted a maintenence practice called "Reliability Centered Maintenance" the focus was take some large mechanical device and determine MTBF (mean time between failures) and what the root cause was. This also provided best practice maintenance periods and other improvements...in short- reducing heat on a gear reduction unit caused the MTBF to more then double its life expectency...and simply dropping the temps by a mere 25* caused the oil analysis to determine that the viscosity had also not broken down as fast either...including contaminents and H20. How did we cool the unit- putting an external oil cooler on it, we also switched to fully synth oil and the results were remarkable!

 

The coolant temp is not as important in drying oil as the oil temp is. Set your DIC to oil temp and drive around for a while(1 hour) and decide for yourself.

I have the 160 T-stat and the oil temp reaches 200-210(plenty hot enough) while the coolant stays at 180 or below at cruise. That said, I just replaced my radiator with the Dewitts A97A and I expect the temps to run lower now but it's hard to test when it's snowing here. However, after pulling out the stock radiator, it's no wonder why the LS1 runs hot. Small passages, restricted coolant outlet due to the built-in tranny cooler, and restricted air flow...why bother with a T-stat at all when the radiator is so inefficient. I'm up to temp. in 1 mile and the T-stat is wide open from then on.

If you want to reliably cool your engine, change the radiator. And if you want to save the $100 corvette tax on a new Dewitts, PM me for the dealer as he's not a CF vendor (yet) but is a Dewitts authorized dealer. If you do though, at that point I would go back to a 170 t-stat.

*You won't need the radiator unless you track it though. Street driving won't heat up your engine enough to worry.

6speeder is correct, it's all about emmissions and milage for the CAFE standards, nothing more. We can all agree that "heat kills."

 

I do not know what stat is in mine (I have not touched it), but the DIC shows the fuel mileage not reaching peak until about 180 degrees. Mine runs between 180 and 200 on the highway. I drive my car about 500 miles a week (300 on the freeway) and watch the numbers everyday. It seems that efficiency and power should somewhat parallel each other, eg less friction = more power AND fuel mileage!

David.

 

This is an excellent write up in replies to the question. The Corvette Forum is a great data base for searching information. I shall ear mark this POST for future usage whenever the argument comes up about the 160 thermostat being impractical to use because it doesn't do the job of burning off contaminate in the oil.
Thanks to all
Rsty

 

Thanks all, this discussion is just what I was looking for. I think my new stat is 172F, the car runs like a top, a really fast one, and now I understand more about KR and emmissions.

Thanks!!

 

160 for me. Never did buy that water in the oil story.

I like to launch at the strip with a 180 water temp. The 160 helps me do this.

 

The simple answer is that at temps far below 212 degrees, steam will form and will exit via the pcv system.Take a pan of water and start heating it, steam vapors will start forming at temps as low as 140. End of story!