Ok so from what everyone is pretty much told a lower temp thermostat will give u a performance boost. now is this all because the engine will runner cooler sooner? due to the coolent and water circulating sooner then the engine get's up to a higher temp? and just curious if anyone has "proof" of the actuall performance gain. like a dyno run or somthing. if any difference in performance is achived.... i would only think it would be minimal...if at all.
post any ideas or anything....
Opha

 

There is no performance gain to be achieved by lowering the operating temp of the engine. Electronically managed engines run the best when they are at factory spec operating temp. You will see TONS of discussion here and other places but truth be told most of what you read will be incorrect. The best overall driveability occurs at an operating temp around 200 degrees.

 

I have noticed a difference in throttle responce and acceleration at different engine temps. it feels better at 180* then 220* ... now maybe this is because when my engine is running cooler, my tranny is also probably running cooler.. but i have noticed a difference.... and i have seen some time slips that show a gain too. but then again could it also be from the lower tranny temps that ur gonna get?? thats just my opinion though

 

You sound whole hearted in your statement but I would kinda like to know how you know for sure? Like asked before, any dyno sheets to prove it? As far as I know, high temps are just to make an engine burn cleaner for emissions. I can tell you for sure that I've always noticed a difference in running a 160 stat in place of a stock 195.

 

i remember my TBI ALWAYS FELT(aka *** dyno) way stronger at about 160 then 200. it was a noticeable difference

 

To be honest, when my car is cooler, like 200 or below it runs fine. But when i get ever 220, the car at a stop when i press the gas, kinda hesitates for sec before it goes. I dont know if thats thermostat related or just heat issues, but thats what it does.

Now that i think of, it best be described as this: If i start the car, and start driving around, everythings cool, meaning fine. And even when it does reach like 220 for the first time, its fine. But lets say now its been like 30 minutes and i;m still driving, now its starts that hesitation ****, and it only occurs from a dead stop.

So i guess u could say there is some sort of performance increase when its slightly cooler.

I dont know if im making sense, but this seemed like the best opportunity to tell this little annoyance.

I'm hoping when i figure out how to configure my ECM chip, i can change when the fans kick in.

 

I know this generates a lot of differing opinions and that's what were are here for. My opinion comes from a lot of research into the subject and discussion with people in the engineering side of the auto industry. What they all seem to aggree on is that the hotter the engine runs the more efficient it is. This efficiency translates into fewer emissions and increased fuel economy. My personal experience was a decrease in fuel mileage with anything other than the stock 195. One thing that was also mentioned was stability in operating temp. A lower temp stat depending on driving conditions will generate a larger swing which I was told was not desireable. There is discussion about how well the ECM can control fuel delivery at different temps, and that is really the issue. Personally, I am not totally convinced that the ECM can properly manage all the emission controls for best efficiency when the temp of the engine is bouncing all over the place. When one considers that roughly a third of the energy from the combustion process translates into useful HP it would seem to make sense that with less emissions more of the fuel's energy is making it to the rear wheels.

 

my car actually runs better when it is at normal temp around 210...when it is cold it seems like it no power at all and it bogs...i know it doesnt help that i have an out of tune stock lg4 qjet on a rebuilt 350 but when its at about 210-220 it runs the best..

 

ive noticed a difference in performance when i put in my 170 stat. when im on the highway the temp chills around (150) between the first 2 yellow lines on my guage. at around that area i feel a performance gain cause it stays colder. throttle response is better overall. i dunno bout other peoples cars but mine enjoys the cold weather.

 

On the same note as BORLAZ06, generally all of our ECM controlled vehicles will enjoy cold weather and that is because the ECM will richen the Fuel:Air mixture per cubic ft. of air. Cold air has higher amounts of oxygen as compared to hot air which typically has lower amounts of oxygen per cubic ft.

So, bottom line cooler temperatures, overall will result in more power. However, I do agree with Danno in that higher temps result in decreased emissions and improved fuel efficiency, and these higher temps also help burn off carbon which tends to accumulate in the plenum, intake ports, on valves and pistons. But when going down the 1/4 mile strip, the ECM is in fuel enrichement mode (provided that you have the gas pedal to the floor) and the previous statemtent goes out the window.

 

A cooler engine means cooler under hood temps = more HP, simple as that.

At the track with my car running, close to 40* cooler I ran a lot faster.

emissions cars do like to run a little warmer for emission purposes though, to fully burn the fuel.

 

Smokey Yunick (you all know who that is right?) says that the SBC operates best at ~200*. He means efficiency, HP, idle stability, etc. Anything much warmer than that and you can overwhelm any 'hotspots' in the engine where coolant doesn't flow very well.

The only way an ECM richens the fuel mixture is from cooler air entering the intake that it senses using the IAT. That's why some companies make a IAT relocation kit, so you can move the IAT to a 'cooler' area and try to fool the engine into thinking it's actually getting cool air. The only draw back is that no matter what the IAT says, the O2 sensor has the final word.

The only explaination for some of you experiencing increased SOTP readings is that the underhood temps are increasing the temp of the intake charge as your car warms up. This will warm both the fuel and the incoming air. That means less fuel and less dense air. But the warmer the engine is, the better it'll perform.

That's why cast iron heads (with everything else being the same) will make more HP than aluminum. They retain heat longer, which is a big plus during the combustion process.

Just remember this.....

Cool air/fuel in.
Hot burn.
Hot exhaust out.

That's the best method for producing HP.

 

You pretty much said it all. All I know is that from my checking into this subject I found that the research is into materials that will handle more heat. The direction many manufacturers are going is into hotter running engines. The problem is simply being able to contain underhood temps and present material limitations. I guess the perfect scenario is to air condition the intake and run the engine as hot as possible.