Hal..........now this buggs me, I copied this from the www net somewhere and didn't save the url. I'm gonna try and type some of the pertent parts, al'fresco.
Dirt Cheap Supercharger......by Steven A Richmond
"ok her it is. pleases don't laugh until you've tried this. it really works.We've used this thing for many differnent jobs where we needed a lot of volume of air at low to moderate pressure levels and the almost always work out very well.
All you need is a smog pump. People don't realize just how efficient these little pumps are. At 8000 rpm you can feel a strong air blast from a one inch pipe attached to one of standing over 25 ft away. They will actually produce up to 60# or more and if you block the airflow completely, the pump will stop a 5 hp electric motor.
Most of them take in air through an impeller right behind the drive pulley, which is fine for most purposes, but some are equipped with a separate inlet port complete with a small air filtering device, which can prove useful in certain cirmcumstances. There are piles of them in junkyards which you can actually get for as little as $5.
Some of these pumps have more capacity than others I like to play with the ones for 350 Chevy police cars or 454 bigblock trucks. The only thing that will ruin these pumps is heat. 90% of pump body is aluminum, so they are relitive light.
Be careful how much intake pressure you apply to a high compression engine, keep it under 8 psi on a 9:1 comp engine.
We attached one of these to a friends son's go-cart engine (B&S) and the power increase was very impressive. One should suffice for most motorcycle engines........end quote
Like I said, big smogpump on our low compression, slow turning 120 cu/in engine could be an interesting adventure...........Dell