Blower daffynitions......

[Jim W]

I last ran a bower motor about 25 years ago. It was a Mag case 8/71. Things have changed a bit since then.
Been looking around for a alcohol blower (mainly RBSsuperchargers.com) and the new terms have me confused a bit.
Can someone clarify a few things for me please?????
Mainly looking for an explanation of terms and the pros and cons.
Alum vs mag cases.
Std. helix, hi helix and retro helix? Or is retro the bottom opening?
Cast rotors vs billet.
Rotors stripped with all teflon vs teflon and nylatron.
Top opening sizes. 10.5"--13"--buzzard, I have a bird now.
Bottom opening sizes. 15"--std.--large--retro pie cut
Front gears vs front and rears.
This will be for a 468 BBC 12-1 on alcohol, mainly lake use but might like to go racing in the future. Any suggestions on size, rotors, openings etc????
Thanks for the help.
Be good, Jim

[Jim W]

No one has a comment or suggestion?????
Be good, Jim

[BOOGEYMAN]

you running 12 to 1 sattic compression on alcohol and want to put a blower on top of that? how much boost are you planing on runing? Aftermarket or filled block?
got some buddies that run 11 to 1 on alcohol and blower set ups in their race cars but 12 to 1, blower and alcohol dosent sound like it's going to be a lake boat....?
Travis

[DetroitJim]

Lots of blown alky lake boats around here, just depends on how impractical you are willing to put up with!
I last ran a bower motor about 25 years ago. It was a Mag case 8/71. Things have changed a bit since then.
Been looking around for a alcohol blower (mainly RBSsuperchargers.com) and the new terms have me confused a bit.
Can someone clarify a few things for me please?????
Mainly looking for an explanation of terms and the pros and cons.
Alum vs mag cases.
Mag is lighter weight, costs more, wears out faster, don't need it unless you are racing Top Alcohol.
Std. helix, hi helix and retro helix? Or is retro the bottom opening?
Standard helix is stock GM, hi helix has more twist. Retro means the bottom opening extends forward past the ends of the rotors, makes the blower air flow more back to front. More bucks, more efficient, see comment above.
Cast rotors vs billet.
Stock rotors are cast, bigger blowers are made by adding an additional segment of a stock rotor. Billet rotors are stiffer so they don't twist under high boost. See comment above.
Rotors stripped with all teflon vs teflon and nylatron.
Teflon is white, wears out faster. Nylatron is black, used on rotor tips for longer life and tighter clearances again for racing only.
Top opening sizes. 10.5"--13"--buzzard, I have a bird now.
Bottom opening sizes. 15"--std.--large--retro pie cut
Many new blower cases are now using a pie shaped bottom opening, more efficient. Does'nt need to be retro unless you are racing Top Alcohol.
Front gears vs front and rears.
Rear gears keep the rotors timed under high boost, racing only.
This will be for a 468 BBC 12-1 on alcohol, mainly lake use but might like to go racing in the future. Any suggestions on size, rotors, openings etc????
Any teflon stripped 8-71 or bigger will be fine, make sure it is clearanced for alchohol.
Thanks for the help.
Be good, Jim

[Jim W]

Boogeyman,
by lake use I didnt mean playing around all day long.
Would like to flop it into the water once in a while and go out and get my need for speed thing met. Once I feel comfortable with the boat, may want to go to a Kentucky drag boat event.
Right now the motor dynos right around 750 HP injected on gas.
Would like to run that swapped around to alcohol for a while and then put on a blower starting around 1,000HP and be able to swap pulleys to gain more HP until the thing scares me.
I think a 10-71 would be ok but theres lots of nice used 14-71 blowers around.
Just wondering about what size blower and what options to try and get used.
By options I mean, std. helix, high helix, opening sizes, cast or billet rotors etc..
Be good, Jim

[Jim W]

Thanks for the info DetroitJim,
I just got a estimate for both new and used parts from RBS superchargers.
In the quote was....machine intake manifold for burst panel, INDY
Can you tell me what INDY means?
Also, what's the advantage of a burst panel over a pop off valve?
Be good, Jim

[DetroitJim]

I dunno about INDY, maybe they want to sell you a blower manifold made by Indy cylinder heads.
A popoff valve is just a spring loaded pressure release, if there is a backfire it prevents bending or damaging the blower rotors. Standard equipment on most manifolds.
A burst panel is a sheet metal piece about 3" by 6", does the same thing but it is destroyed if it blows open. Required for Top Fuel and Top Alcohol, not mandatory for bracket classes or blown gas. You don't need it, if you buy an intake with one just get a spare or two for $20.00 each. I have blown burst panels just from hitting the rev limiter on my blown gas hydro.
DJ

[@theRVR]

I dunno about INDY, maybe they want to sell you a blower manifold made by Indy cylinder heads.
A popoff valve is just a spring loaded pressure release, if there is a backfire it prevents bending or damaging the blower rotors. Standard equipment on most manifolds.
A burst panel is a sheet metal piece about 3" by 6", does the same thing but it is destroyed if it blows open. Required for Top Fuel and Top Alcohol, not mandatory for bracket classes or blown gas. You don't need it, if you buy an intake with one just get a spare or two for $20.00 each. I have blown burst panels just from hitting the rev limiter on my blown gas hydro.
DJ
and when you run out of burst panels, cut up a beer can it will also work to get you through the weekend.

[Jim W]

and when you run out of burst panels, cut up a beer can it will also work to get you through the weekend.
LOL
For a low boost motor, use Coors---->Lite....
Hi boost motor, Use Guniness--->Stout
Be good, Jim

[adjones419]

Jim,
Glad to hear you are getting away from gas and might try to make some KDBA races. Hopefully the SLDBA/KDBA co-points deal will go through and we'll have some nice races down in Kentucky.
Anyway, I'm in the process of building a new blown-injected alcohol setup myself at 12:1 compression. Should be easy 9's in my flatbottom and then step up to 8's when I get the tune-up figured out. I bought a Littlefield 8-71 aluminum high-helix retro blower with teflon and nylatron for starters. The retro refers to the "front discharge" on the blower. A standard helix has 60 degree rotors, while the high-helix has 120 degree rotors. With a high-helix, you'll want to run port nozzles as well as the hat nozzles. Remember, anything larger than a 10-71 and you will need an offset for the magneto (assuming you're going to run a mag...I personally am not!).
The INDY blower manifold is a very expensive piece...you won't need it. Just go with a BDS competition manifold. Go ahead and go with the burst panel...probably won't need it, but peace-of-mind to have it. You say lake boat, and that means water running through the engine in my mind, but make sure you fill the block with block filler.

[Jim W]

With a high-helix, you'll want to run port nozzles as well as the hat nozzles.
Can you explain why this is necessary?
Be good, Jim

[Jim W]

This is from the inside top alcohol forum.
Someone was asking the difference between a top fuel blower and a alcohol blower.
I thought this was a interesting response.
A top fuel blower is NOT a high helix retro blower but is considered to be a standar blower. A standard blower has 60* twist to the rotors and dumps the air directly out of square holes under the rotors. A high helix retro blower has 120* twist to the rotors and dumps the air out of a pie shaped opening in the front part of the bottom of the blower. It takes a lot more horsepower to drive a standard blower because more air is trying to push itself back up through the rotors from underneath and that creates heat and uses up horsepower. High Helix retros need less horsepower to run, make more boost and have a cooler air charge. My recommendation is to use a high helix retro for alcohol and not a standard blower.

[adjones419]

Can you explain why this is necessary?
Necessary? Not quite the word I would use. Better? Maybe. It allows you to fine-tune each cylinder as well as evenly distribute your fuel.

[jimsplace]

I am running gas with a 14-71 and carburetors in a flatbottom. I know gas and alcohol are not the same, but let me tell you why I went the route I did.
When I started looking to go with a blower my thought was to get an 8-71, it is what a lot of people run. As I talked to a number of people I trust, I was told an 8-71 on a 540 is somewhat marginal, because of the heat created in the blower, a 10-71 would be more acceptable. OK, I thought, I should go with a 10-71. Then I talked to the blower people and their response was if you are going 10-71, go to 14-71. The reason was it would be turned slower for the same boost, creating less heat, and they only cost slightly more. So now we have a 14-71.
I also went with the Indy cylinder head manifold with the burst panel. For a lake boat, if the burst panel goes, you are not going anywhere. So, I opted for a pop-off valve. To do that, have a block at least 1/2" thick machined to fit the pop-off area, and purchase a pop-off valve kit and install it on the block. I suppose this could be done on any manifold with a burst panel. The Indy manifold is taller than most manifolds and I think will accommodate a number of distributors under the blower. I run a crank trigger with a MSD crab distributor and there is about 2 1/4" of clearance above it. It is enough to remove the cap. One down side is the distributor can not be removed with the blower in place. (motor can not be oil primed through the distributor location). You can remove the blower belt and spark plugs to do the same thing.
I understand on alcohol, heat is not usually an issue. You indicate you are going with injectors which, with alcohol is probably a good thing. I already had the carburetors and I know nothing about injectors. My set-up is still new to me, but is starting to work well. I had a few bugs at first, but seems to be coming around now.
Good luck