D_Echo

here's a discussion with one of my friends over the week about turbo size vs performance.

.............................this is one topic where i have a very good feeling i am completely wrong, so if anybody has time, please let me know where i am making my grand mistake.............

To me, it seems that a larger turbo vs. a smaller turbo, when both producing the exact same boost levels there are two sides to the matter. on the small side....it would spool faster, and on the big side, it would be able to provide enough air during increased rev range.

However, i don't see how a larger turbo produces MORE POWER with the same ECU programming. I know somebody here will know why. So please fellas, i'm just not seeing it.

I know that with a larger wheel & housing the air flow through the intercooler and into the intake manifold will be at a higher volume potential. BUT....since the only tubing/routing that has changed is the turbo housing itself, and the boost pressure is measured at the manifold and it seems to me that no matter how much air you're able to flow, if the boost is the same and the hp should be the same.

Take me to school PLEASE, i've searched everywhere to no avail.

BOOSTD

more air volume.

On3.8.TuRBo

i would guess the more turbocharged air the better....

Audi2ptzero

and will do so at a lower air temp. Boost is just a measurement of pressure not the amounts of air. To see this you have to look at the maf readings. You will notice that a bigger turbo will give almost twice the amount of g/s at the maf during the same boost level.

hman_a4

also - remember the 'ideal gas law' from basic physics/chemistry: <b>pV=nRT</b>

3rd page of article.<ul><li><a href="http://auto.howstuffworks.com/turbo.htm">http://auto.howstuffworks.com/turbo.htm</a</li></ul>

WYSIWYG

in no way my T28 feels better than my k04 setup in the lower RPMs

xr4tic

small turbos are good for low boost levels, big turbos are good for high boost levels.

The stock turbo is rated for about 7psi, that is where it is most efficient. When we crank the boost up to 17-18psi, the efficiency drops. At 7psi, the efficiency may be around 70%-75% or so, at 17psi, it's probably closer to 60%

A big turbo at 17psi will provide the same boost level, but at a better efficiency. It will have about 70-75% efficiency at 17psi.

A 10% increase in efficiency means cooler air, which is denser (more oxygen = more power) so you will be flowing more air at the same boost level.