tomcat

Hi Doug:

Yes, intake manifold design could cause differences between cylinders; which one do you think would have better distribution?

You can never talk about boost without talking about temperature. Here's an interesting comparison of temperatures @ 10 psi boost:

Blower - Intercooler inlet/outlet

Roots - 222F/137F, based on 60% compressor eff and 60% intercooler eff
Centrifugal - 194F/108F, based on 75% compressor and 75% intercooler eff

The centrifgual makes less heat to begin with and the bigger intercooler does help a lot. This kind of charge air temperature difference does make a difference in the onset of detonation and that's why the centrifugal can make more power. Or you can look at it as a bigger safety margin.

We measure parasitic loss on our blower systems using a NA mule engine on the dyno. We don't apply any boost to the mule engine, we just use it to drive the supercharger(s). We know the HP of the mule, and after we install the supercharger drive belt we measure lower HP on the dyno. The difference is the parasitic loss, measured throughout the RPM range.

There have been tests using the very same intercooler and engine. At the same boost level the centrifugal made more power than the Roots, primarily due to parasitic loss, since charge air temperature was only slightly lower.

We are not going to SEMA. We are displaying in Key West at the races in November, in the Florida Powerboat Clubs "vendor village".

RumRunner

Tom,

Thanks. Hopefully the Vendors village doesn't rain like it did last year!