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Old 11-19-2001, 04:18 PM   #1
Puckaveli
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Cool Can being cool make you go faster. No really!

I was messing around with my obd-2 software and I found that the cooling fan doesn't kick in until 190 degrees. I used to have my Mustang setup for 165. Can the hotter coolant temps actually rob any power? I don't expect to get any noticable power gains from this. I was just curious.
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Old 11-19-2001, 05:57 PM   #2
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actually yes, but i'm not sure about tampering with the fan. Its basically the same concept as an Intercooler, the intercooler keeps your engine cooler, therefore giving you magically more horsepower. I know in some cases in turbo applications, an intercooler added 40hp to some cars just by simply keeping the car at a cooler core temp. I'm not sure if i'd tamper with ure fan though.



-Kevin
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Old 11-19-2001, 06:01 PM   #3
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The intercooler doesn't keep your engine cooler... actually, it may make it run hotter.... but that's a byproduct... what an intercooler does is cool the air going into the engine. cool air is more dense, and you therefore get more air, which means you can add more fuel, and get a more powerful combustion.
Engines run more efficiently they hotter they are, BUT they can't be too hot or you get other problems. These problems can also rob power, as well as just plain ruin your car... I wouldn't mess with the fans unless you are having problems w/ already running too hot or too cold...
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Old 11-19-2001, 09:58 PM   #4
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You're that lucky bastard that has only hot gal friends... oh wait, that's OT...

PS, post those pics again...
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Old 11-19-2001, 10:20 PM   #5
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Figure this... your thermostat opens at 180 degrees(I really have no idea when Subaru thermostats open). You engine is always going to run that temperature, no matter if the fan is on or not. Turning the fan on at 165 degrees when the thermostat opens at 180 makes no sense. Now if you were to put a low temp stat in the car, like your Mustang probabily had, it would help. Then again, you could possiably run into a whole load of trouble running a low temp stat too. Could be worse. GM car stats open at about 195 and the fans don't come on until 212.
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Old 11-19-2001, 11:01 PM   #6
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You don't ever want ot change your thermostat or your fan settings without changing them both at the same time. The yare set up to work the best together.

However, if you do change the thermostat and you can find someone that makes a lower fan switch for our cars, go for it!

Eric
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Old 11-19-2001, 11:37 PM   #7
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yea, and tell me
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Old 11-20-2001, 12:25 AM   #8
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Actually, IIRC running HOTTER will net more power......

I've looked over SOOOOOOOOO many trucking mags and what not, they always advertize "power" packeges which usualy include a thermostat rated at a higher temp than stock.

This makes sence seeing how MOST of the power lost through combustion is in the form of heat. (someone correct me if i'm wrong) So if you run hotter (in the water jacketing the cylinders) there is less "heat sinking" happening inside the engine, which in turn means less loss in the form of heat transfer...???

Sounds good don't it......i think i'm not spewing forth a load of CRAP.....if i am some let me know please.

Peas,
AaRoN
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Old 11-20-2001, 12:33 AM   #9
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That is wrong.

although, coolant temperature is used for a variety of engine and emission control functions. The coolant sensor on late model engines tells the computer when the engine has reached normal operating temperature. This, in turn, affects fuel enrichment, spark timing, operation of the EGR valve, purging of the charcoal canister, etc.

If a colder thermostat is installed, the coolant may never get hot enough to trigger the appropriate control functions in the computer . As a result the engine will run as if it were continually cold, which increases both fuel consumption and emissions. Too low an operating temperature also increases cylinder wear.

However, that is pretty extreme. I don;t really know how to explaine it becuase I don;t know how the laws of thermodynamics affect a car to be perfectly honest, I know that using a little colder thermostat and fan switch will help you gain a few ponies.

I've done dyno tests to confirm them but the graphs are buried at work. I elieve it has something to do with the fact that sonce the ingine is colder overall, when the intake charge finally reaches the cylinder, it is a bit colder than it would be with a hotter running car. Plus it helps fight detonation!

Eric
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Old 11-20-2001, 02:03 AM   #10
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Cool......thanks for te info
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Old 11-20-2001, 02:31 AM   #11
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I have a idea of why a hotter engine might burn more effeciently. Fuel atomization..... Simply when the fuel hits a hot surface it turns to vapor form and combusts better. Hotter the surface, the quicker and more completely it vaporized.

Just an idea... no tech to back it up.
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Old 11-20-2001, 09:34 AM   #12
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I had a feeling that the ECU would be designed to match the thermostat and cooling fan as far as other coolant temp functions. I do know one thing after I changed the thermostat in my Mustang I went through 3 heater cores in 1 year and the car never heated up right again.

My car always feels faster with my girls riding in them, so being cool does make em faster.
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Old 11-20-2001, 12:15 PM   #13
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An engine that runs hotter will be more effecient. Heat is energy, and the more of it that is conserved the more energy can be used for work. IF you could run an engine at 1600 degrees, once it reached operating temperature, heat could not be accepted by the engine any more (heat can only transfer to cool) in reality, there would always be some transfer, but if it were possible to run that hot, we would insulate the engines to keep as much heat in them as possible, obviously cooling systems would not be needed.

This is theory, in reality there are problems with this. Such as the intake charge temperature with an engine so hot. We wouldn't be using gas anymore with high engine temps, so maybe even higher engine temps would be better. Starting the engine would be horrible, as things expand at different rates in different parts of the engine. All sorts of things would need to be figuered out, not the least of which the metalurgy (or likely alternate materials).

While right now, what is "right" (ie hotter engine being more efficient producing usable power per unit of fuel) Its not what current technology can support, so we amplify parts of the system that produce power gains. Like cooler intake temps. Notice though that effeciency and power are different. Lowering intake temperature increases the amount of fuel needed to have a correct A/F ratio. So we could add fuel to our very hot running engine through lower intake charge temps as well, and since it produces more usable work per unit of fuel, it would produce more power than the "normal" engine. How much, I don't know.

What it comes down to is that a hotter engine is more effecient, and with the same amount of fuel, will make more power. The problem is that CURRENT engines are run as efficently as possible (relitivly, we are talking about mass produced cars, that have alot of other considerations) and by making them run hotter, we are not amplifying a good part of the CURRENT design, and thus are not getting gains in the output from running them hotter. (The engine already runs to hot for the current design. If it didn't, why do we need to cool it.)

Greg
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Old 11-20-2001, 09:51 PM   #14
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So......I'm partly right.....kewl..
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Old 11-20-2001, 10:14 PM   #15
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Why does "REDLINE" Sell Water wetter. And the phrase "Keep your engine cooler".
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Old 11-21-2001, 05:41 PM   #16
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I don't know much about Redline Water Wetter, but I imagine that it makes you cooling system more efficient by changing the properties of your coolent. My guess is that it makes it more conductive to heat, allowing it to pick up more heat energy in the engine, and pass it along faster in the radiator.

They probably use the slogan "Keep your engine cooler" because it keeps your engine cooler.

Greg
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