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+--- Thread: My name is Travis and I have a problem (/showthread.php?tid=868)
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- .RJ - 08-28-2004
MichaelJComputer Wrote:He swears it'll be running this weekend, I call
BS
He's said that every weekend for the past month.
mongooze Wrote:Props to Chris of course for having the fortitude to keep going back and turning up the boosthock:
More boost = more better
- mpg9999 - 08-29-2004
KPWSerpiente Wrote:^We are talking about one 2.0 liter engine, mine. And two different turbos one which will flow a certain amount of air in a minute and another that will flow more at the same boost.
I don't have maps for both turbos (I have never seen a map for the evo16g) but lets pretend my current smaller turbo is 90% efficient at 20 psi (just pretend with me) and this new larger one is only 10% efficient. If the wheel on the less efficient one is large enough it can still flow more air and make more power.
Quote:Or maybe IM wrong, and dont know what im talking about. I like getting into a good technical argument. Always a good learning experience.
You aren't saying anything wrong, it just doesn't have anything to do with what is going on here. Small wheel putting out a small amount of air vs a larger wheel putting out a larger amount of air. Engine size and boost remain constant the only difference is how much air one compressor pushes out vs another.
-T
It still wouldnt make more power. Especially with it only having 10% compressor efficiency, but thats besides the point. You can't magically increase the VE of the motor to make more power.
Mf=DI x displacment in CI x (rpm/2)xvolumetric efficency
The only way to get more air into the motor is by increasing one of those variables. There is no way around this. Let me break the equation down a bit more so we can examine this closer.
DI is the intake air density.
DI=(boost pressure+atmospheric pressure)/(R constant x 12 x (460+intake temp). R is equal to 53.3.
So, you can make more power, or get more air into the motor, by increasing displacment, increasing rpm, increasing volumetric efficiency, or increasing intake air density. Just because a turbo CAN flow more (like 45 lb/min v 35 lb/min), doesnt mean the engine can swallow that extra air.
A turbo can make more power by increasing the intake air density by being more efficient. It also increases power by decreasing backpressure, which results in less robed power to power the turbo and increased VE.
Hopefully that makes sense.
-Mike
- KPWSerpiente - 08-30-2004
Sure.
-T
- Mike - 08-30-2004
.RJ Wrote:MichaelJComputer Wrote:He swears it'll be running this weekend, I call
BS
He's said that every weekend for the past month.
he lied.