Dirty Howie

Ok...I have a 04 coupe. Mods are CAI (TRAP), very soon to have 3.42 gears. Will get headers/exhuast/heads/maybe cam in future. Live in Los Angeles Calif. area. Car runs 192-196 when moving goes up to 220+ if sitting in traffic.

Seems like there are three different stats to choose from: 160/172/180. Which one should I get. Is there more power from the 160? Have heard that 180 is the optimal running temp.

I understand fans/tuning may be necessary to reap full beifits.

Can someone clear this up for me......Please

Sandra Bigwoode

There is no benefit to changing out the stock t-stat.

Heat is energy and you are already losing 35% of the caloric energy to the coolant, a necessary evil.

The t-stat temp is only a floor limit so a 160 F. will never go below 160, but once the engine is fully warmed up on a hot day the t-stat is wide open nearly all the time, and only air flow and your fans will reduce your temps to safe levels.

On normal driving on cooler days, you car will never reach design temps, ie 190-194 F., waste fuel, waste power and contaminate the oil further since the moisture and other bad guys never get hot enough to boil out of the oil as they would at 192 F.

Why does NASCAR run their engines at 240 F.? Power, pure and simple.

Although they don't use t-stats just restrictor plates, since the engine is fully warmed up pit side when they hit the track.

The car engine is a heat engine, the cooler you run it, the less efficiency and power you will make.

If you really want to run cooler, forget the t-stat and just set your fans to come on at 180 F. although it's not a good idea as outlined above.

Geneus

Yeah, and I suppose that the gas inside those pistons is combusting at a real "cool" temperature.

Sandra Bigwoode

No, but if the cylinder and head surfaces are cooler than normal, you will lose heat, thermal efficiency and thereby power. GM and all other stock car makers have very good reason to install 192 F. t-stats OEM.

If making more power were as simple as changing a t-stat, why did GM redo the heads and cam on the Z06 to increase power? The t-stat remained the same.

I know some people who believe you can make ice cubes faster with hot water than cold, since somehow the hot water 'freezes' faster... =;-]

dkdonkim

very interesting point & knowledgable..
so, what do you think of your "optimal temp." is?..if, let's say 240 is, many of us living in hotter areas are wasting their time & not really enjoying such moment since we are probably stuck in the traffic if the temp. reaches 240..i am sure very few people can experience such optimal temp. on freeways unless they drive 150 mph for an hour or so..and, i am sure many of us living in colder areas will probably never experience such optimal temp..

i agree with your point saying that heat is the energy, but can it be also harm & stressful for some engine parts and/or drivetrain?..i am experiencing "unnecessary" heat problems now, and trying my best to reduce my oil temp. a bit..correct me if i am wrong..

such an enjoyable site it is..
thanks..

Sandra Bigwoode

Yes, excessive temps beyond design limits are harmful to engines and components. If you seeing 240 F. on a stock LS1/6 engine there is something wrong with the cooling system.

Optimal temp for LS1/6 engines is 190-194 F. Nascar racers never sit in traffic and are always moving for optimal airflow. They also do not start off cold on the track like street cars do, they have the coolant and engine warmed in the pits before they make their first track run.

Their engine components are all designed to work with 240 F. and the high pressures that ensue, it would defintely be uncool to run those temps on a street LS6, the standard seals and engine dimensions would not tolerate those temps for long without failure.

mdhmi

185-190 F is ideal according to my tuner.

Mark

Mr. Lucky

Hmm...
http://forums.corvetteforum.com/show...post1547846519

mdhmi

BW1. What is your question ? All I was saying is that 180-190 is within the 'ideal' range and that a running street temp of 200 is not a 'problem'.

Mark

BHP

I have seen many LS1s on the dyno. Temps in 185*-195* range produce the most power. A little more at 187*. My street testing shows around 185*-190* with a big radiator, t-stat, fans set correctly. The t-stat needs to be fully open to the radiator below 185* to run in this range.

simpleman68

I have had the same question, but am puzzled by some of the responses as they seem to be blanket statements.
Optimal temperatures I'm guessing would be different according to what components you've added to your otherwise stock engines.
A stock motor probably does run best at 190ish due to the fact that the fuel mix controlled by the computer is factory set to that temp.
GM, like other auto manufacturers get pressure from the EPA to keep hydrocarbons lower in their emissions. Having a warmer stock T-stat setting will lean the fuel curve.

But, if you change your set up and reprogram your fuel curves I don't see how heat is going to add hp or performance for atleast one basic reason.
1. cooler air is denser than warmer air = more efficient combustion

I'm not any expert here, just wanting clarification. I'm used to people striving for colder air charges in their intakes to produce more power. That holds true for N/A engines as well as any forced induction or NOS application. The larger, more efficient intercoolers always produce significantly more power.

BTW my chemistry teacher taught us hot water DOES freeze faster due to the fact that the molecular activity, advanced by the heat, causes more space between molecules allowing the water to reach the freezing point before water at room temps.
He could've been lying I guess.

TXSTICK

OK, here it is (the hot water/freeze thing)

http://math.ucr.edu/home/baez/physic...hot_water.html

Sandra Bigwoode

The PCM will give you a constant 14.7:1 AFR at normal operating temperature except at WOT. This is why a car with 405 bhp can get 30+ mpg on the highway. This is not the only reason GM uses a 192 F. t-stat, power and emissons are also better at stoich and partial throttle openings.

We are not adding heat here; we are trying to keep what we can in the engine at 192 F. and normal fan turnons, not 160 F. t-stats and accelerated fan turnons.

IAT is irrelevant here, the discussion is focussed on keeping the heat in the combustion cycle in the combustion chamber, not dumping it to the coolant with a cooler t-stat and fans coming on far too early.

Did you call him on it? He was either incompetent or trying to challenge a class who did not do any of the reading in the textbook.

Are you a person who on a hot day splashes HOT water on his face because it feels cooler than splashing COLD water on his face...?

simpleman68

I've never tried it out. Hmmm another puzzle. Will the hot water open pores and in turn cool the skin surface more efficiently?

simpleman68

Awww heck I can't even reply to a quote correctly here!
I'm still learning. Sorry if it got muddled.

Sandra Bigwoode

Opening pores has nothing to do with it, skin is cooled by sweat evaporating and removing heat from the skin surface.

0rion

The only question I have is how much effect do you believe temp has on timing limits? An example would be sitting at a light next to someone who's car is idling at 180 and you're sitting there smoldering at 220. When the light turns green are you gonna be able to have as much timing without knock as they are? My point is at what temp does detonation become a problem on the street?

Dirty Howie

Good question!

I look at everyones sigs. And it seems the more mods they have the more likely they have a lower stat as one of the mods. Why are they all putting in this mod if it doesn't produce some positive horsepower results???????????

simpleman68

I was just being facetious
Thanks for taking the time to post your earlier info though, it was helpful.

leaftye

It's pretty simple if you seperate things. You want heat to stay in the combustion path, and only in the combustion path. Cylinder head bowls heat are treated to keep heat in the cylinder, but out of the rest of the cylinder head where it would affect coolant temps and Intake Air Temperature (IAT). GM moved the exhaust port on the 3-valve GENIV motor to help with heat soak on the IAT. Some engine builders go even further by coating valves, headers, oil pans, and the inside of engine blocks. These coatings also help keep heat in or out of the oiling system, depending on the expected temps for the application the engine will be used in.


Knocking because of Engine Coolant Temps (ECT) or IAT indicates a problem with the tune, to include incorrect setup of the sensors. There are tables in the PCM that account for changes in IAT and ECT.