8-71 vs 14-71 boost

i have a interesting problem im trying to solve. we run a 14-71 hi helix ml with just the teflon strips in it in a kb 511. we are limited to 30% od at normal altitudes, and 43% at high altitudes. i also have a 8-71 ml std rotor with both sets of strips and we are allowed any od on. do you think the 8-71 could make as good or better boost with the unlimited od, or will it not pass enough volume to do it? havent tried it yet, wondering how it might work. any thoughts? im sure the 8-71 would take less hp to run, but not sure about the boost numbers. thanks, dan

 

It's interesting that you say the 14-71HH only has Teflon strips, in the 32 yrs I've been there I have never built one that way, a good rule of thumb for different blower sizes if all is the same is about 6% per size, for example, an 8-71 would be 18% less than the 14-71, the high helix will always make more power in the 35-40 % overdrive range

 

It is a mooneyham...

 

Either way the high helix will still be better, remember boost isn't horsepower if it makes to much heat to get it and the parasitic loss of turning a small blower faster is greater,

 

Super sucker

well, since thats not going to work out, what does a new lb20 hi helix do compared to say the mooneyham unit? is it better than a kobelco superman for a 30% deal?

 

So far every application that is running an LB-20 has had success and is very pleased, from nostalgia fuel, tractor pullers and AA- gas cars, we have done a lot of work to get the boost up, manifold temp down, and parasitic loss of turning the supercharger lower, so far all of those goals have been met, our of the shelf blower doesn't need any "upgrades" we do everything that we can to our production models

 

8/71

We run a 8/71 mooney ham retro blouwer on a 500ci chevy with a small intake air size,we have 29% od and it makes 25-28 lb off boost how much will it make @ 40% od .

thanks