Tell me about heat loss
11-13-2001, 01:53 PM
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Re: Tell me about heat loss Yep, if you think about it all the force on the piston comes from the expanding gasses of the combustion reaction. Since Volume is directly related to heat as that increases so does volume, so your pressure at an instantaneous point does also.
Now when you take heat out of the equation you reduce the extent to which your gasses expand, reducing power output.
Where does it balance out? You want to run the engine as hot as possible without detonating/pre-ignition? Now where exactly is this magic point? It depends on just about everything, and is different for any given combination - hence we normally run far on the cool side just to be safe. After all is 5-10hp worth a cracked piston? On a race car it might be worth the risk as you can better control all the variables and are putting less demand on the car - and every last hp is critical. On a street machine? My vote would be no!
With that in mind, you can still shift the balance in one direction without getting in trouble. Thermal coatings are excellent in this regard - even if you don't pick up much power you will pick up some mileage.
Chris
Now when you take heat out of the equation you reduce the extent to which your gasses expand, reducing power output.
Where does it balance out? You want to run the engine as hot as possible without detonating/pre-ignition? Now where exactly is this magic point? It depends on just about everything, and is different for any given combination - hence we normally run far on the cool side just to be safe. After all is 5-10hp worth a cracked piston? On a race car it might be worth the risk as you can better control all the variables and are putting less demand on the car - and every last hp is critical. On a street machine? My vote would be no!
With that in mind, you can still shift the balance in one direction without getting in trouble. Thermal coatings are excellent in this regard - even if you don't pick up much power you will pick up some mileage.
Chris
11-13-2001, 07:16 PM
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Re: Tell me about heat loss this is why reverse cooling works very well, it keeps the heads cool, preventing detonation and pinging, and it keeps the block much warmer, which means less heat loss and less friction.
11-14-2001, 12:20 AM
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Tell me about heat loss I realize heat equals horsepower, and I've read a bit about this a few years ago but forgotten almost all of it. Now I need to explain it to someone and cant find the right terms and reasons.
Heat loss = why cars with lighter aluminum blocks make less power due to heat retention and mass, why you dont see 1 liter V12s (not enough heat in each cylinder) etc.
I mean we use aluminium heads because they lose heat more rapidly, so there is less chance to detonate. But what is optimal? We ceramic coat pistons to keep heat in the chamber, correct? Could you ceramic coat the combustion chambers too?
Heat from the motor goes to 1 of 3 places, out the exhaust, into the cooling system/block, or working to push the piston down.
Heat loss = why cars with lighter aluminum blocks make less power due to heat retention and mass, why you dont see 1 liter V12s (not enough heat in each cylinder) etc.
I mean we use aluminium heads because they lose heat more rapidly, so there is less chance to detonate. But what is optimal? We ceramic coat pistons to keep heat in the chamber, correct? Could you ceramic coat the combustion chambers too?
Heat from the motor goes to 1 of 3 places, out the exhaust, into the cooling system/block, or working to push the piston down.