Quote:
Originally Posted by 95 imp
So, if I run my engine 100* cooler, I pick up 10% hp?
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You would find in the real world the difference is negligible. If you are talking about intake air temperature and not coolant temperature, then you theoretically get something like 1 hp for every 10 degrees cooler intake air temperature. This is just because the engine is actually taking in more oxygen and has nothing to do with thermodynamic efficiency.
You always want to run your engine (coolant temperature) as hot as you possibly can while still being safe from engine damage. You'll see a lot of people don't under stand thermodynamics. The reason why there is aftermarket (and even I guess Katech has one, which is a well respected company that knows what they are doing) thermostats that are cooler, is to try to let you cheap and compensate for running inadequate lower octane fuels on a engine that was designed to run on higher octane fuel.
If you understand things like conservation of energy, the way heat flows, and a little bit of thermodynamics (you don't even have to understand entropy) you will see by having cooler coolant temperatures more heat >= energy >= horsepower is sucked out of your combustion chamber, goes into the coolant, and gets wasted out through the radiator into the air.
Back in the 70s Cummins did some research into trying to eliminate the cooling system on engines for the military, the goal was more to make the engines more reliable by making them not require cooling, and not necessarily more efficient. They used some exotic ceramic materials and achieved the highest efficiency for any engine, I believe to this day but I haven't seen an official paper on it. Of course the engine they made was probably way more unreliable and probably had millions of other issues (ceramics are brittle and prone to cracking) and I'm sure was extremely expensive. But basically if you don't cool and engine you make it more efficient and more efficient also means more available horsepower.
If you don't believe me that the radiator and cooling system "sucks" power from your engine, go out and see how your engine drives when it hasn't warmed up versus when its fully warmed up. There are some factory limiters and rev limiters at extremely cold temps for a few seconds, but generally until the engine is fully warmed you can sense a loss in response and power. This is because the engine block and coolant is very cold and is "sucking" heat from the combustion chamber at a way higher rate than it does when its fully warmed up. This heat could be turned into power at the wheels, so its kind of like until your engine is fully warmed up, you are "short circuiting" it.
Also all these people claiming that lowering coolant temps for power increase because it "heats" the incoming air too much, should really go do some heat transfer calculations and report back. The amount of heat transfer is so negligible especially to a moving fluid.