jimman

Timing retard at 190 now who came up with that one.

haljensen

Somewhere between 194° and 212°, see;

http://forums.corvetteforum.com/phot...a/1124/ect.jpg

Don't know who to credit for the chart, I got it from the Forum on 11-1-06.

6Speeder

This isn't rocket science guys. The stock thermostat stays fully closed till 186 degrees. It won't let the engine run below that. Replace it with one which allows the coolant to shed heat by flowing through the radiator and it will run cooler. The reset fans are needed for stop and go traffic, normal airflow will suffice at speeds above 45 or so.

rwebcon

My two cents.
In Phoenix at 117 driving at 70mph the temp never when over 198.
In a place like Phoenix where its NEVER cold the 160 stat will not count against you!

DJ'sZ

I knew it was somewhere in the 190's just wasn't sure where exactly. Yep from my understanding and what little knowledge I have with the tuning on the LS7's the ECU, as we all know, makes corrections in timing for IAT and Engine Temps which can pull a substantial amount of timing, I think, going slightly overboard in protecting our precious LS7's...GM warranty at it's best.

The car feels more consistant on back to back runs...maybe it's my imagination...placebo effect...or I just "think" the car feels better at lower Water/AI temps. Hell I just figured it couldn't hurt anything.

DSteck

My friend reprogrammed my fan logic so that the fan comes on harder at lower temperatures, but I never plan to go to a lower thermostat. The engine was made to operate at temperatures expected with the stock thermostat, so I'm not going to screw with it. With reprogrammed fan logic, I can sit at a traffic light for 5 minutes idling after running the car pretty hard, and maintain about 200º coolant temperature. Your internal components wear better around 200º than they do at 160º, so you risk some engine longevity with trying to run ***** out at a cooler temperature. If anything, I'd only drop to a 180º t-stat and lower the fan logic, simply to allow the car to cool down to sub 190s faster. It's all about design intent, and how things were catered to fit that...

Foosh

You're right, it isn't rocket science. A 160 stat will open sooner than a stock stat, but once both are opened, they BOTH stay open. You have no more cooling capacity. If you reprogram your cooling fans, they will run essentially all the time, and give you a bit more. As I said way above, with a 160 you will gain a slight advantage of a few more minutes of cool running, which comes in handy for certain people hanging out on 1/4 mile straight strips of asphalt.

If you stay at 1600 RPMs in 6th all the time on the freeway, you might see it running cooler much of the time. Of course, contrary to the "old-school wisdom," that's not necessarily desirable for the car and getting proper oil temps for good lubrication. If Corvette Engineering thought that was a good idea, they would have put a 160 in it.

All these "cooler with 160" reports are comparing "apples and oranges" because different people are reporting on different driving styles. If you run at high RPMs for sustained periods as road racers do, your 160 stat will run no cooler than a stock stat in this car.............ALL OTHER THINGS BEING EQUAL.

allegretto

Rocket science, hardly. But it still is Science. In fact,if we neglect trajectories and gravitational considerations it is not far removed. The transformation of potential energy containing elements to power and heat are common to both processes and the issues specifically surrounding heat dissapation are central to both as well.

So let's stop with the "my car runs cooler than your because I use a lower thermostat" discussion because that's not the end of the curve that's of as much concern. If your car runs 170 while going downhill at 64.362 mph it isn't that much different than mine running at 186. I think that some have noted that optimum operating temps may not necessarily be the coolest due to oil viscosity and mechanical considerations. So, I don't really know about that myself and I think it near-moot for most situations.

What concerns me is what happens at the other end, when coolant and oil go beyond 260. This is where 15 degrees one way or the other can effect output and perhaps be instrumental in catastrophe. At this end, it really doesn't matter what stat you're running.

My solution is to leave this whole thermostat issue behind. If incrementally lower temps at relatively low engine speed or a few more moments of cooler running is your thing then just leave the darn thing out. I'mputting in a Ron Davis radiator and oil cooler this week. I expect this will go a long way to padding down the temps at high RPM.

6Speeder

You aren't impressing anyone with your "engineer speak". I could do the same, ( BS EE, 23 years USAF; 4 as a test engineer, 12 developing weapon systems for the AF and 8 of those as a rocket scientist ) but it's pointless for this forum, plain talk is best.

Back to keeping your engine cooler: The advantage is it makes more HP. The way to do it is relative to your usage. If you are really doing long distance road racing, not just 5 or 10 hot laps at a time, then you will need major changes to the cooling system. Most folks here don't do this, and they don't need major changes to an already excellent system, just fine tuning because GM set the car to run hot for emissions, not peak HP.

For most folks the solution is easy:

Run a 160 thermostat, change to 25% coolant and 75% water, with 1 bottle of Water wetter or similar product, and tune your fans to come on sooner and at a higher percentage. Hint here: don't set the 192 degree percentage higher than 20% or they will run almost all the time. That's all you need. Set like this, my temps are low enough that the PCM doesn't pull timing based on ECT, and I get no KR, but high enough that the oil does burn off contaminants and is not so viscous as to cause early engine wear.

DJ'sZ

Thank You...couldn't have said it any better...!!

bernrex

So ... tell us engineer that you are ... what engine temp would provide peak HP ?

6Speeder

As hot as you can run it without having it pull timing or getting KR. I shoot for 185 on a dyno (short duration pull, low load) or 180 at the track.

bernrex

OK .... so it sounds like GM (Katech) has it set about right ... to obtain peak power & good emissions.

From thermodynamic standpoint ... a higher operating engine temp is more efficient. May need to boost octane however, to see the power benefits.

jimman

The next time you do a pull take the time to measure the inlet air temp and water temp at the peak hp and post your results, You'll be in for a surprise. Been there done that several times. Also, check your fuel mix on short trips with cold engine. There is a term called cylinder wash down you might be interested in. Extrapolate that out over 70K miles with the majority of your travels being short runs with low temps.

DSteck

Being the engineer in the automotive industry that I am... I'm going to stick to what I said, which is the same kind of things that other people I work with have talked about. I don't trust those EEs one bit!

Norm_427

Does Water Wetter really work? ?

I can't seem to find objective tests or articles on the subject. I want to believe it does work and if it just helps lower temps on the track from 220* to 215* then I'll get some (but I don't really want to reduce the % of anit-freeze to lower temps).

6Speeder

I have. Many a time. I once ran the dyno at a local shop. Best power always with cool IAT, hot oil, hot diff and tranny, and ECT as warm as it would stand. Usually for LS-X engines best ECT for power was at 180 to 185. As for cylinder wash down it's not an issue for cars with properly functioning injectors. You are still stuck on carburated vehicles. Even on cold start conditions the injectors won't wash down the oil from the rings/cylinder walls.


Water wetter won't do much for a 50/50 mix, only works on the water portion.

jimman

Well then maybe you can explain this forum member's numbers

Just dynoed the car after installing Jim's F1 race filter and tune. Here are the comparison data. Both the stock and modified runs were done on LG Motorsports' Dynojet.

BONE STOCK ( 63 deg F ) ( 34% humidity )

Run ----- Oil T ----- H2O T ----- RWHP ----- RWTQ

1 -------- 149 ------ 198 -------- 456 ------- 424

2 -------- 158 ------ 210 -------- 463 ------- 431

3 -------- 153 ------ 205 -------- 458 ------- 431


F1 AIR FILTER AND HALLTECH TUNE ( 70 deg F ) ( 30% humidity )

Run ----- Oil T ----- H2O T ----- RWHP ----- RWTQ

4 *** invalid data (wheels spun on dyno) ***

5 -------- 167 ------ 214 -------- 484 ------- 446

6 -------- 156 ------ 203 -------- 481 ------- 453

6Speeder

Easy to explain. Bad test methodology, giving poor data collection, yields inconclusive results.

1. You didn't test cold enough. The first, and coldest run, was only 198. That's already too hot and the PCM is pulling timing.

2. Your run #4 SHOULD have been a cold run (180) without the mods it you really wanted to test the effects of ECT changes.

3. Where is the cold run with mods?

You tested nothing and proved nothing. If you provided this data and the conclusion that hotter is better to a group of systems test engineers you would get laughed off the podium.

bernrex

Easy now ! His data does show that as engine temps (H20 temps) increased ... RWHP increased. And the data was for temps above 180.

Do you think its a twin peaked curve ... with a 180 peak that is higher than the peak his data gives ?