by Cryptonic26 » Sun Jan 08, 2006 9:52 pm
On a very very small scale it does. not enough to matter, but slightly, possibly measurable.
The vacuum pressure is directly linked to two variables. Combustion energy, and the pressure difference between combusted gasses and gasses in the exhaust system.
That is, part of the combustion cycle in each piston is used to pull another piston down, sucking gas into the cylinder. Part of that cycle is used to push another cylinder up (evacuating the combusted gasses from the cylinder).
The less pressure in the exhaust system, the less energy it takes to push that piston up, the more energy is available for vacuum/drive.
If you remove a lot of heat from the exhaust system (via radiator setup), you reduce the pressure, improving overall engine efficiency by a small bit. It actually WILL increase vacuum pressure!
Again, i'm not sure it's enough to matter in the total scheme of things, but it's there nonetheless.