Blvdbrawler

Okay guys, I think I saw this a few times a long time ago but have not seen any updated data. We all know the LT4 does not like heat and theres been some discussion back and forth regarding if its a good idea to swap out the stock thermostat to a 160 degree to help keep the engine cooler.

On my C6Z I ran with one and the car ran like a charm keeping the engine temps just under 190 pretty much all the time. (Car had mods with a tune) Certainly the LT4 is a different animal and the argument is that if the engine designers thought it should run cooler then they would have given it to us stock. The other side says its for emission purposes only and the higher temps always pulls timing and power from the car. I dont like running over 200...Im sure theres nothing wrong with it but Im old school and I do know the more we can keep the temperature down typically the car runs better.

Anybody install one in their Z? If so, what are your thoughts? Thanks...

Jimmyz28

Great question...

Higgs Boson

Have you searched this forum? We have argued about it plenty of times already, lol.

You need to edit a couple things in the tune, including fan settings, to get it done properly and I do think it is worth it, I run a 160 and it never goes over 175 or so in the texas summer unless I am pounding on it.

being in NY however, I would be a little less enthusiastic about it for winter use as you will have to run your car pretty hard just to get the oil up to temp. if you park it for the winter then that's a non-issue.

tzoid9

This is interesting....do you regularly run over 200F? Or maybe, do you find yourself running over 200F on a hot, humid summer day, stuck in a traffic tie up and you have the A/C blasting? If you're talking about normal & occasional spirited driving (not Tracking) and you find yourself regularly over 200F, then you likely have a problem. I'm not sure what the C7 stock Z06 stat is, but typically they run 190 or 195F. If you're running always over that, what function does that thermostat in your car have? It's designed to have the engine run at the optimum temperature that the engineers designed into the car. I used to change thermostats all the time in 60's and early 70's cars, but no longer on the newer engines. Maybe, just maybe, if you lived in Phoenix where the temps can run in the 110+F range, there might be some logic, but if you're in the Northeast as your signature indicates, I'd not recommend that maneuver!

Bill Dearborn

The thermostat sets the floor and doesn't do a thing for the high temp that can be reached. When running hard 20 minute sessions in 95 degree heat I see mid 220 coolant temps and mid 270s oil temps. On the streets and highways I don't really see anything close to that with the stock thermostat. On the street there is no way you are going to ever notice whether the system pulled timing or not. You can't open the throttle wide open long enough to notice. A 5 second wide open burst on the throttle is enough to get you put in jail if an LEO is around and that won't even get you up to the max HP rpm level.

Bill

Higgs Boson

come on now bill, i know you downshift!

davepl

NASCAR runs their cars >200F. They don't actually run thermostats, it's done with airflow control through the grill I'm told, and the cooling system is open loop. But they could run them as cold as they'd like at those speeds, and they choose not to.

GM doesn't do. NASCAR doesn't do it. I've done it before. But now I wouldn't.

Performance aside, it'll increase wear, and perhaps more important, sludge (since the vapors don't boil off as readily from the engine oil).

Higgs Boson

NASCAR runs hot because they run at redline for hours and hours and the oil is hot as f.....not to mention they do this one behind the other with virtually no airflow through the radiators not to mention aerodynamic compromises (not unlike our trusty Z06s).

Do you think they could run 160 degrees under these conditions (especially with the bulk of the season through the summer? No way.



"A cool engine makes more power than a hot engine. We know that from dyno tests, and we know that from time slips and lap times. If you walk through a NASCAR garage before Nextel Cup qualifying, you’ll need hip boots because the teams use shock cooling systems to lower their engines’ temperatures to 60 degrees before a qualifying run. "
http://rehermorrison.com/tech-talk-55-keeping-cool/

The idea that hot temps are good for power is absolutely silly.

MrBlackZ06

I run 160 thermostat on my C7Z, much better oil and coolant temperatures compared to stock unit, specially on highways, even after full throttle the temp gets down quicker and it is super easy for DIY, just make sure the engine is cold for no less than 24 hours. My tuner set the radiator fan to run on lower temp.
I am very satisfied with it.
One downside for me the oil temp takes long time to reach operation temperature, sometimes I have to drive on higher RPM to heat the oil so I avoid full throttle with oil temp below operation temperature.
FYI I don't track my car.

Jimmyz28

ACS55

My car is AT LEAST one tenth quicker in the quarter when starting the quarter at 150-160 degrees coolant temp vs 195, possibly more.
I will say that the A8 tends to hesitate between 1st and 2nd more when NOT hot, but the car still runs a quicker time.
If it wasn't for needing a tune to reprogram the fan engagement, I would have a 160 therm installed already.

0Terry@BMS

Disregard my post. Read tables wrong.

davepl

I don't know exactly what 200MPH of airflow through an open heat exchanger would do, but yeah, I think it would sufficiently cool an engine.

Remember the excitement over whether ignition advance reduced operating temperatures? I went straight to my retired NASCAR engine builder and spent an hour or more with him talking about ignition lead, thermostats, NASCAR, and how they cool them. He convinced me I was right but that I didn't need to convince anyone else. His comments were, if I may paraphrase:

- "Why do you give a sh$#t what strangers on the Internet believe if they're wrong?"

I almost stopped there, but I pressed on. He's kind of old and curmudgeonly.

- "If your buddy doesn't think EGR goes up when timing is retarded, he's never looked at an EGR probe in person. And where does he think this heat goes?"

I wanted to correct him that it wasn't my buddy, just some guy on CF, but I let him go on.

- "We don't run a thermostat. We control engine temperature by the amount of airflow allowed into the radiator." I asked: "You mean like the old Packard with the adjustable grill?" and he said "Sort of".

They could run those motors a LOT colder than they do, but you'd really have to know the tradeoff for aerodynamic drag that airflow creates.

Suffice to say that in my mind the "hot ticket" isn't running the motor at 160F. But you guys, my "buddies", can run your Zs as cold as you like. I just won't run mine like that. I'll run it as GM designed. If I had my choice I'd run the block and heads as hot as I could but the intake as cold as possible, with thermal separation between them. Not really possible.

Technically, I suppose, you want the chamber to retain as much heat as possible short of detonation with the intake path leading to it somewhere around zero Kelvin.

l2vette

Exactly!!
Don't be fooled by the notion it will make your engine run cooler. The temperature rating is when the T Stat opens only, it does not reduce the operating temperature of the cooling system.

ACS55

Terry,

Forgive me I don't have the tools displayed here nor do i know how to read the chart. I am however, speaking from experience and well documented run times and engine temps.

Are you saying that the engine MUST BE AT 194 DEGREES, and NOT COLDER (than 194), and NOT hotter (than 194)... in order for the ECM to not pull timing????

Andy

jim2092

As you know, this table is entitled "The multiplier is used to proportionally enable or disable this feature." The feature being the affect of ECT on spark. The table next to it in the tune is entitled "Base" which has a very different affect on spark vs. ECT where it starts pulling degrees of timing at 194* but adds under that.

0Terry@BMS

You are right. My bad! I should have checked that table too. Deleted post.

0Terry@BMS

No at quick glance I read the tables wrong. Looks like you are OK being colder.

ACS55

I was thinking that sounded strange. Thanks for the clarification.
It looks like I need to "step away from the holley carbs and the dual points" and learn to read timing tables...

Higgs Boson

This applies to a few people in this thread....