delta opening in set back efficiency

hi all!
i need to make a set back plate for a standard helix 8.71 khul blower with a big bottom opening,run at 34% overdrive.
it is to go on a 454 CUI KB/MOPAR all aluminum wedge engine,that will run at 7500 rpm max,injected on alcohol,in a door car.
should i stick to the "square" bottom opening shape of the blower or would there be any improvement in overall blower/engine performance in a delta shape opening in the setback plate?
this blower has new teflon strips.
thanks a lot for any input
cyril

 

thanks a lot for your answer,Mike!
is the delta shaped bottom opening specific to high helix blowers?
i was explained,i i understood well,that this opening was meant to direct air "right" at the bottom and prevent some of it from going back up through the rotors,right?
can't the set back plate opening be used to obtain the same effect?

 

The Nostalgia TF and FC use a 60 degree rotor in a delta opening 6-71 case. Under 20 % od but 10,000 rpm engine speed.

 

I have heard of guys using a setback plate with a delta opening and thinking it was doing the same as a blower outlet that is a delta opening. I don't believe you are gaining by doing this, probably making worse, because this needs to be very close to the rotors, as in part of the blower case.

 

Set back plate for open case should match blower then be blended into manifold. However a slight sharp edge at the edge of the blower might help a little.

 

The plate deal might be lipstick on a pig but that is where the delta outlet was born...with a plate.

Dave Koehler
http://www.koehlerinjection.com

 

thanks a lot for all the infos!
a happy new year to all the ITA community!