blower loss

[joukaishou813924]

can anyone tell me of a place that will tell me the blower loss rate for a 4-71 blower or a 6-71 blower at 15-25psi?
i've tried to serch da web and found, well not much, the project in mind is a smaller motor and while i'd like to go bigger, i want to make sure it can at least turn the blower....

 

[CR55]

I would think that Weiand, Blower Drive Service or one of the many other companies that sell and service blowers should be able to help with tech info. Good luck with your search. CR

 

[Gastrick]

I can't help you with a parasitic supercharger loss chart but I would think a 6-71 on a very small displacement engine with 15 psi boost would be asking for trouble. Just out of curiosity, how small of an engine are you talking about and is it a street or race engine? You may have more problems with catastrophic explosion than parasitic loss.

 

[joukaishou813924]

it was an idea for twin charging a 2.1L inline 4 eninge, i've tried looking up wieands info but the smallest motor they talk about was a 289 v8....
and wheen i tried eaton their website was equally confusing giving me lots of info in metric and only havve one example to go off of.

 

[eyesore]

Gastrick is absolutely right. I think you would be better off putting a turbo on an engine that size.

ISore

 

[DJ3100]

Get "A Complete Guide to Street Supercharging" by Pat Ganahl.
ISBN 978-1-932494-93-8

The short story is that there are too many variables to accurately access the amount of horsepower a blower consumes. Eaton seems to be the only company that has any test data and it all amounts to a "depends on the situation" answer.

This book will explain why you might not want too big a blower for the engine.

 

[R Pope]

A 2-71 would be lots on a little banger like that! 2X71=142 cubes, and that's a 2-cycle. Just a rough guess I'd think it would put twice the air in the cylinder as it would normally get, which means about 15 pounds boost. Sure, that's not dead accurate, but it gets you in the ballpark.
You'd better have one mean banger if you're going to stuff 25 pounds in it without pushing the crank out the bottom!
Maybe look at a 3-53 unit, or if you want to push it, a 4-53. They're a lot more compact than their bigger brothers.

 

[Krooser]

25 psi would create an awful lot of heat...I'm not sure an intercooler would even cool it down enough. Anything over about 8 lbs on the street would be pushing the limit. A small Rootes-type blower would work good... just remember that too big is just as bad as too small.

 

[RPM]

If memory serves me correct I think the Toyota MR2 had a small 4cyl and was supercharged. You might explore that.

Just me but I think a turbo would be a lot better for that smaller motor. No HP loss driving it. It would be a lot easier to fab all the tubing to make it work.

 

[joukaishou813924]

they use mp90 on mr2's

 

[Krooser]

it was an idea for twin charging a 2.1L inline 4 eninge, i've tried looking up wieands info but the smallest motor they talk about was a 289 v8....
and wheen i tried eaton their website was equally confusing giving me lots of info in metric and only havve one example to go off of.

Twin-charging? Using a Rootes-type blower AND a turbo?

 

[jfg455]

remember 15 psi from a roots style blower equates to alot more CFM than 15 psi from a turbo. Even different size turbos will produce different power levels with the same psi due to more or less CFM

 

[joukaishou813924]

true, and i have some planning to do to find out cfm required to have boost at that low of an rpm

 

[Krooser]

You can adjust the boost with the pulleys... right now my 6-71 is set for 8 lbs... one pulley change can make a lot of difference.

Remember you have a very small engine at 2.1 liters... only so much extra air can enter and exit the heads.. the limiting factors are cubic inches and port/valve size. In your case smaller is probably better.