front discharge vs retro

What is the difference in a front discharge and a retro blower Which one preforms the best and why I have a littlefeild high helix front discharge pie shaped opening, what kind of boost can I expect I have never run a high helix blower just a std helix what kind of power difference can I get out of this vs a std helix will my tune up be alot different? Thanks to all

 

As far as I know, front discharge and retro are the same design just different mfgr. terminology. Look for a pocket milled out in the front bearing plate and an opening at the front of the case. A retro blower will have to be moved back about 1.5 inches over a standard blower hence the retro plates.
The hi-helix rotor doesn't neccessarily make more boost than 60 deg. stuff it's just more efficient. Jim Oddy claims about 250hp for the helix rotor and another 100hp for the retro case/bearing plate. I switched from a large outlet 14-71 with straight rotors to a worn out hi helix retro and picked up 13mph with the same boost. If you can find it, the blowers with the small opening on top and bottom are the latest design and make the most power.

 

THERE IS TWO BLOWER STYLES ONE KNOW AS THE DELTA OPENING AND THEN THE RETRO. THE DELTA HAS THE PIE OPENING IN THE CASE BUT NOT CUT INTO THE FRONT BEARING PLATE ALLOWING THE USE OF A STANDARD INTAKE. THE RETRO HAS A 2IN. THICK FRONT BEARING PLATE VERSUS THE 1.5 IN. THICK BEARING PLATE ON A STD BLOWER AND HAS A POCKET MILLED INTO IT ALLOWING THE AIR TO ESCAPE OUT THE END OF THE ROTORS AND MAKING A MORE EFFICENT SUPERCHARGER. THE RETRO WILL PERFORM BETTER AND SHOULD MAKE 3 TO 5 POUNDS MORE BOOST OVER A STANDARD DELTA. BUT AS STATED BELOW YOU WILL HAVE TO MOVE BACK ON THE MANIFOLD. TYPICALLY THE HI HELIX OVER THE STANDARD WILL COOL THE AIR BY OVER A HUNDRED DEGREES AND TAKES LESS HORSEPOWER TO SPIN OVER A STANDARD 60 DEGREE HELIX ROTOR. IF YOU ARE RUNNING AROUND A 500 INCH MOTOR WITH 11 TO 1 COMPRESSION AND RUN A 1/4 MILE WITH SAY 50 OVER ON THE BLOWER YOU CAN HIT BETWEEN 35 TO 45 POUNDS OF BOOST MOST OF THE TIME. ON YOUR TUNE UP YOU HAVE TO MOVE YOUR NOZZLES AROUND A LITTLE AS NOW ALL THE AIR IS BEING DUMPED IN THE FRONT. BUT THIS ALSO DEPENDS HOW FAR BACK YOU MOVE THE SUPERCHARGER REARWARD. GOOD LUCK JR