PaulW

Okay....it's been a long time since I've actually had to make calculations....it's not that hard, but figuring out how to do that square root thing was not easy! :-)

Anyway, with a centifugal blower, the blower speed squared is proportional to blower pressure.

So at redline (6200 RPM), you have your max boost.....at half redline (3100 RPM), you have 1/4 the pressure (half speed) because of the squared relationship.

This curve represents an ideal Pressure Ratio (ratio of desired HP to existing HP) of 1.33.

The Audi specs all state that the KW is 220 at 6,000 RPM for the ABZ engine, which correlates to 295.02 HP from my calculations, don't know where they get 300 HP. I have used the KW numbers converted off a graph of the ABZ engine for this chart.

Note that the power now goes up from 6000 RPM versus down because of this squared relationship.

<img src="http://www.audipages.com/upgrades/supercharger3.JPG">

I haven't run the numbers yet, but I think it's going to be hard to get any more than this out of an ABZ engine which is at 10:8 compression ratio (CR). It will need to be intercooled.

But I think the curve looks great! Around town in normal driving it will be like stock and have all its torque, and when you give it gas.....it's gonna go once it gets above 3,000 RPM!!!

My spreadsheet shows stock HP 295 @ 6000 RPM (292 @ 6200 RPM) and supercharged HP as 385 @ 6000 RPM (388 @ 6200 RPM).

pw

skiracer

Looks promising! Let me know if I can be of any help......

PaulW

I wanted to get somebody to review the calcs that I've made.....and you're on my list!

I looked at the motor today, I might have a way to modify it to accept the bracket....need to go back and look again.

I have to say, doing this research is a lot of fun!

tozoM8

You know where to find me if you need some custom fabrication.

PaulW

I figure between me and you, we'll come up with something very cool in the design dept.

KaMaKaZieP -ALUMIN8-

What about the variable intake manifold.. would we benefit from keeping the runners long and disabling the changeover with forced induction? If so then the hp curve will be quite different.

PaulW

But the whole purpose of the manifold is to achieve low end torque with long runners.....then high end power with a short entrance into the cylinder with the runners changing.

So I don't know how much it will change it.

PaulW

Would have to take into account pressure losses across the intercooler.....but that's about it.

obLu

Most of the sc kits for other cars seem like they're just after burst power since they don't include an intercooler. I can't imagine what the power curve starts to look like when the intake charge gets heat soaked ... probably worse than stock.

Dan McBoost

<img src="http://www.ma70.com/danmac/bumperoffforlip.jpg">