High Helix, Retro vs std opening

OK, long story short. I have a 10-71 Mooneyham on a 8.0 drag boat. 500" engine. It is their "ski blower" meaning it is stripped to case, but not rotor to rotor. Cast rotors. I need to make about 5# more boost. This one quits making boost after turning over about 22%.
Obviously stripping the rotor sides would help. But how much?
What are the advantages of going to a high helix? Then Hi Helix Retro?
It is a bracket boat and always will be, so I don't need to make a million pounds of boost. Probably 20 max!
What do you think?
Oh, yea. I'd like to stay with a 10-71 because I am set up for that. MSD crank trigger with large diameter cap on dist. Don't want to go offset drive this, set back that, spacers here and there.
Thanks
Wags

 

call this number it is mert littlefield ask for andy wilfong he is a blower goo roo very very smart myself I think i would have them send me a retro plate it is the pie opening..Dave Lowe
714-992-9293

 

Hey Steve if you go retro you will need to set the blower back. Killing the distributor deal Craig

 

blower

A high helix will make hundreds more horsepower than std rotors in the same case at the same od and boost. A Kobelco or other trick blower can pick up even more. The cheapest/easiest deal is to get a old 1471 hihelix maybe even non retro.Use the short crab cap distributor or drive it off the front of the engine.The market is full of 14's but 10-71's are hard to find.

Mike

 

Hi Steve, you can also have them make you a plate with the pie opening and set it up standard, we have made several over the years..Dave

 

Is there any chance that one of you top guys could post a picture to show the difference between the H/H & the H/H retro as I'm not clear about the two. What are the advantages of the retro? What should minimum set back be?

 

This is not a retro, but a Hi-Helix (120 degree rotors)


A retro blower would have an even further cutout on the "pie" opening towards the front of the blower to where you can actually see a little of the front of the rotors.

See the link below of one of JR's at RBS for a retro style case...

http://www.rbssuperchargers.com/Store_Detail.cfm?ID=151742&InfoID=3921

 

So, a high helix has the small pie shaped cut out. The retro exposes the front of the rotors.
High helix rotors do not go with a standard open bottom then, right?
I probably should buy a worn out 14 and the crab cap deal. I only need the extra ass for 1 race. Easy enough swap.
A cool Blower shop 10 with the 18 point strip sure would look good, though.
Thanks
Wags

 

retro

The retro setup will have the opening cut into the front bearing plate. The retro design doesn't gain nearly the power of the high helix rotor.
A Kobelco superman has the rotors slid back in an extra long case and you can see the entire front of the rotor...kinda like extreme retro.
I know you boat guys like polished blowers but an ugly black Kobelco makes those others look like tunnel rams.lol.

 

How much will the pie opening change my cylinder distribution. It is great now. I hate to start over.
Boat guys...we are a bunch of characters. LOL

Wags

 

I agree w/ Mike....going from standard 60 degree rotors to hi-helix 120 degree rotors is a huge increase. According to Littlefield, a "retro" case is another 150hp gain. I'm not sure if the delta or "pie" opening automatically suggests it's a hi-helix, just front discharge. But it does keep boost from creating heat on the bottom of the rotors. Most move the blower back a couple inches to get better distribution of air w/ a "pie" opening, whether it's a retro case or not.

Josh Long

 

So, I could put high helix billet 18pt rotors in my case?
Wags

 

Well, good things come to those who wait.
My boat racing has an old 10-71 mooneyham competition piece in his garage. (I actually knew he had it but thought it was the same as mine) He said bolt it on and try it. If I like it replace it with a wore out 14. I have a ski Mooneyham 10 sitting on there. Everything "should" swap right over.
Wags

 

The competition mooneyham was pretty played out. So back to this question...
Will doing this make a few extra pounds of boost or some extra hp?
Wags