hot rod blower

I have this magazine saying that the classic hot rod blower is an exhaust scavenging pump from a 4-71 or 6-71 gmc diesel.\

1) what is an exhaust scavengin pump?

2) how expensive is it to buy one?

3) how difficult is it to install as a blower?

4) where can i find one?

5) what is a 4-71 or 6-71 diesel (what do the numbers meen)?

any help would be greatly appreciated.

an exhaust scavenging pump was an air pump they used on old diesels to suck the air out of the combustion chambers after igntion to let the new air in without forcing it in. With the new giant turbo diesels this isn't an issue.

you can buy them here: http://store.summitracing.com/default.asp?target=edepartment.asp&N=120+4294925239&x=17&y=12

They are bolt on kits for ford and chevy small and big blocks. If you don't have one of those engines you need to either find an intake manifold made for a weiland blower or make one yourself.

The numbers 4-71 and 6-71 means 4/6 cylinders, each of 71ci. This is how the two stroke diesel engines was designated.

As you might know a two stroke engine can't breathe by itself. If you take a look on a small two stroke engine you will find that it uses crankcase compression to feed the air to the cylinder. This isn't used with larger two strokes, instead they have a separate airpump to feed the cylinders with air. On the diesels 4-71 and 6-71 the compressors was used for exactly that. See picture below.

http://www.yachtsurvey.com/Fourstroke.jpg

Impressive!