This same thread seems to pop up every few months, with the same old arguments. The naysayers are typically well educated folks who point to the laws of thermodynamics, or examples of race engines that are tuned successfully to run at higher temps. NASCAR is a good example. Others point out that lower operating temps result in more emissions (possibly true) and more water vapor and toxic deposits in the oil (not so true).

We have street cars, not race cars. Our engines are controlled by a very sophisticated computer, and the tuning parameters are not optimized for maximum performance, they are optimized for street use, emissions, gas mileage, and engine safety. Take the LSx engine out of the car, ditch the computer, and yes, you may be able to tune it for better performance at higher operating temps. Maybe....

YEARS of practical experience have shown that 160 thermostats are an effective, practical, and inexpensive performance mod for our LSx cars. Many tuners include them in their upgrade packages, and for a reason. They do not lower oil temps that much, but do affect coolant temps. In most cases you do not need to change the fan controls, although that can also be a benefit for hot weather locations, or for track use.

It's really not that big a deal, as it will ONLY prevent a performance reduction under certain conditions. It does not magically improve performance under all conditions. But there is VERY little downside, and many benefits to those of us who are interested in maximizing performance, especially at the track.

 

Wow! I love this forum. You really can learn alot by asking questions around here.

I'm checking in with Jermemy F. who did my HP tune to see if he would need to to tweak it any. I know he already adjusted the fans to come on earlier and ahole lot more etc.

Thanks again for all of the replys!

Dewman

 

NO! As Hitamn99 stated above, GM has other criteria that they NEED to meet, that we are not concerned with, or AS concerned with here, as they HAVE to be.

Following your "logic";
*If LT headers REALLY produced more power, then "GM would install them for you"
*If Longer duration cams made more power, then "GM would install them for you"
...and so on.

 

Your graph is intake air temp NOT engine temp.

The thermostat does not control intake air temp. Sorry.

A cooler engine does not generate as much power as a hotter engine with the same intake air temps within somewhat broad parameters.

Besides, the engine in our cars will run above the thermostat temp so putting in a colder one does nothing on a properly warmed up engine. A waste of time and money.



Doug

 

If you'll read his post completely, you'll see that he is talking about the IATs being related to the proximity of the sensor on top of the upper radiator hose. If the temperature of the upper radiator hose is lower (cooler thermostat), then IATs are lower, thus pulling less timing. It's a fairly simple concept.

San

 

Not for me. You'll find all those with 160* t-stats run cooler on a properly warmed up engine vs the 187* oem t-stat. In fact, on the very day I installed my 160, my oem temps were high 190's. Not less than one hour after installing my 160 and warmed up, my temps were in the high 170's. Thus, well spent time installing and a great value for $20.00 spent

I will agree with you on the importance of IAT temps. This is where the closed system cold air intakes become important in keeping your IAT's around ambient once you are moving. Of course, tuning your IAT's settings also can insure no timing pulled.

 

Where DO you get this nonsense?

Yes, the engines in our cars run above the thermostat temp rating. That is EXACTLY why we need a lower rated thermostat. My Lingenfelter thermostat is rated at 160 degrees, and my coolant temps stay at 178-180 degrees, almost all the time. In really slow traffic, really hot weather, or after a WOT run through the gears, the coolant temp might go up to 185 or so, but then it comes right back down. The 160 thermo works exactly as it is designed.

For you, don't waste your money, don't listen to the real-world advice of your fellow forum members, sponsors, and performance experts, and stay true to your beliefs. Good luck.......

 

Well I definitely believe in keeping things simple and that's why this approach is so lame - it's a Rube Goldbergian and assbackwards way of addressing the issue. Relocating the sensor and insulating the air intake ducting (and taking other steps to get cooler air into the engine) would be infinitely more effective because once the engine is warmed up a lower temp thermostat is not going to affect operating temps much if at all (so this area is going to remain hot) unless you make other changes. All of the available thermostats are going to be completely open once it's warmed up.



Doug

 

Because you say so right? And you're always right because you say so as well? And your expertise is so great and unquestionable that all you have to do is make a pronouncement with no supporting logic, reason or anything else to back it up. Reminds me of my ex-wife.

lol His graph is intake air temp - not engine coolant temp DOH.

See my other response above.

 

what about water wetter? My c5 used to run ridiculously hot when it was 100degrees out. I added a bottle of that stuff and my temps dropped like 7-9degrees on average.

 

Show us a production, hotter running engine w/the same IAT -by the time the air reaches the cylinder, please. (Good luck w/that)


Oh!! Doug doesn't know how a cooling system works! Thanks for reaveling that Doug! Now we're aware of the validity of your posts.

 

Why yes they will! But at different temps (HINT: due to the temps at which they start to open)

 

Actually, this is not true at all. Anyone who has actually tested a thermostat (160, 180, OEM, doesn't make a difference) in a pan of hot coolant has seen that the thermostat just STARTS to open at its rated temp, and then continues to open slowly. At my running temp of 178 degrees, my 160 thermostat is only partly open. I once tested two different thermostats in the same pan, one a 160 and one a 180. They started to open around the same temp, but the 180 opened more slowly. So the rate of opening is just as important as when it starts to open.

To answer the other question, I have seen Water Wetter be slightly effective when mixed with distilled water. I have never seen a difference when it was added to Dexcool, at least not in my cars. Not discounting anyone else's experience.

 

Yeah, depends on too many variables like ambient temps, radiator efficiency, fans etc. I didn't feel like explaining it all to him.

 

Your post didn't recommend relocating anything (hindsight is convenient). You just pointed out that Spin's post showed IATs (which was on purpose). Since a "lower temp theromstat is not going to affect operating temps much if at all", are you advocating a higher temp thermostat? Your logic dictates it is "not going to affect ......".

San

 

While they are 100% correct with the laws holding true, they cant quantify the losses in power they are correct about. Its this lack of info that most of them assume (incorrectly) that the losses in thermal efficiency outweigh the gains from the tuning parameters affected by the swap to a 160 stat.

People with the 160 stat see higher trap speeds and gains on the dyno showing that the gains from egtting around the tuning issues far outweigh the few HP you loose in thermal efficientcy losses.

These race enigines they talk about dont run GM's software pulling timing at crazy amounts and I also bet none of them have intake air temp sensors mounted on top of the upper radiator hoses.

There is nothing wrong with trying to model a system. The issue with it is being arrogant enough to think your modeled system takes every variable into account when it doesnt. All the laws of physics dont over rule a PCM pulling 30hp from timing advance.

Now if we had an ugly air snorkle on top of our hoods like the WRX, pulling absolute cold air in and the IAT took an accurate measurement of this, the engine may see 2hp more from being run at 205-220 degrees.

 

Actually Spin, the ugly snorkle on top of the WRX hood is an air scoop to the top mount intercooler. The intake snorkle is inside the engine bay on the passenger side.

On a side note, if my Corvette made as much power per liter as my WRX, I'd be looking at 900 whp.

San

 

I know its the IAT graph. The IAT sensor is being heated by the upper radiator hose and the IAT reads cooler if the hose is cooler. So the engine coolant temps directly heat the IAT sensor that is the source of the timijng being pulled. The air intake temp sensor is sitting on top of the upper radiator hose. If the hose is 20 degrees higher the sensor reads 20 degrees higher. I scan cars all day long. The IAT's are why the 160 stat works.

A cooler running IAT sensor runs more timing than a hottrer one does because of this MAF/IAT arrangement. As far as generating more power you are 100% wrong and a trip to the dyno will show that to you. It runs more timing when the IAT's are cooler. Until you do the swap and get different results than the countless cars I've done this to, stop touting theory as fact when the facts are proven by people who do this on a dyno.

As for what is highlighter in red, the IAT's are cooler when the engine coolant temps drop. Thats where you are wrong. It does run cooler and the scans show it runs 20 degrees cooler. The IAT sees 20 degrees less from the coolant hose touching the plastic MAF housing so its IAT sensor located in that housing sees lower temps which are logged in a scan. The lower IAT's command less timing pulled and more timing is more power.....all facts that can be seen if you stop assuming things and actually do a scan/test.

A hotter engine will habve higher IAT's.

Your car on a dyno before and after will dyno higher with a 160 stat because it runs more timing.....go prove me wrong.

 

With a 160 degree thermostat, your car at the track will also show consistently lower ETs and trap speeds. This is not theory, this is fact, and has been reported by dozens of CF members.

I do think that a worthwhile mod would be to relocate the IAT sensor to a different place, and to also insulate the air intake from the heat of the radiator hose. This makes a lot of sense.

Afterthought --- even if the ECM monitors intake air inlet temps, not coolant temps, when coolant temps get too high, it can result in preignition (spark knock) and the knock sensors can detect this and the ECM will pull timing.

 

It is undeniably true that lower IAT's contribute to greater power. Even without considering timing, colder air is denser and thus contains more oxygen so burns better (every 5 degrees lower or so will gain an additional 1% in generated power) so you get no argument from me on attempting to lower IAT's.

And, if it is only the timing you are concerned about then tune it out or MOVE THE SENSOR like I suggested, but it is not the only issue. Moving the sensor is easier and cheaper than changing the thermostat. Get a CAI and and then to keep the charge air cool on it's way insulate the ducting, use phenolic spacers and so on - again easy to do. And these mods actually work on the problem in a straightforward and non harmful method.

Running a colder engine (as opposed to lower IAT) both lowers performance and is potentially damaging to the engine. Assuming that a lower temp thermostat will actually lower operating temps enough to make a difference in a sensor that is just close to a radiator hose you run the risk of keeping your engine and oil temp so low that it does not burn off contaminants in the oil and/or does not circulate sufficiently for proper lubrication.

Furthermore, the engine tolerances on the LS series of engines are very tight and precise and are designed to run at the operating temps generated by the stock thermostat. Crankshaft, pistons, rods, cams, pumps, etc.... everything that moves has tolerances and even some that don't necessarily move. The expansion of all these parts that you get from OEM anticipated operating temperature is figured into the tolerances. At these expanded dimensions the engine should run exactly as it was engineered to. Running an engine at above or below OEM specified operating temperatures WILL cause excessive wear or concentrated areas of wear over long periods and affect performance. More reasons to let the engine get to its proper OEM operating temp, and not mess with the cooling system unnecessarily.

Now it's one thing to say "well on the dyno with exactly the same environmental factors and the one and only difference a lower temp thermostat I can demonstrate a difference in power". And I am not denying that it is possible because of the poor location of the IAT sensor. I am only saying that the engines are designed to run most efficiently at a certain temp and there are better ways of addressing this issue. But to suggest that your proof consists of different trips to the track after this mod or that is ridiculous. That, I am sorry does not constitute any kind of valid scientific method of assessing anything, it's just silliness.

Smokey Yunick, Bill Jenkins and other highly regarded racing engine builders have documented the loss in power from running engines cooler rather than hotter. Yunick specifically writes that running your engine at 180 degrees as opposed to 200 degrees will sacrifice 2-3% of its power. That's not 1 or 2 hp as suggested.