Here's a question for everyone running a supercharger. I have a "stock" 1971 455 Stage 1, 4 speed, 12 bolt posi (Chevy type). What I would like to know is if I can run the 8 rib, lower boost system, on my otherwise stock set up? I do know that I have to upgrade the fuel system in order to run the blower. I am also assuming that I am going to have to upgrade the intake to a Performer type manifold to mount the Demon/Holley carb. Right now I am at stock bore, original pistons, original cam. I did add headers, but may go back to manifolds. I also upgraded the flywheel to a billet unit from T/A. Any thoughts as to upgrading the clutch. Currently a stock RAM replacement unit. Also, how much will a stock C-clip type Chevelle 12 bolt handle? Any and all ideas welcome! Jim '69 GS California 455 Stage 1, M20 muncie, 3.31 12 bolt "Passes everything but gas stations"
I'd say you would be ok running no more than 5psi and a solid tune. Any more that that and you will want Better headgaskets and pistons for sure.
I would say that the clutch and axles will only start to be a concern when you start doing 4000+ rpm drops with the clutch with slicks at the track.
This is more of a street car, than strip car. 2000 RPM blows the tires off. 2 & 3rd gears still break loose when power shifting. What kind of power increase would 5-6lbs of boost give me? Since the motor is still fresh I hate tearing it back down. (New rings, bearings, oil pump on a 40K motor). What am I looking at if I need to add the new pistons/rings and head gaskets? Jim
I would not run any more with 5psi without Forged Pistions and good Multilayer Head Gaskets. It's hard to say how much gain as it depends on what's currently being made. You will FEEL the differance though!
I'd be more worried about your transmission than the engine, but you obvisously have to pay attention to both. If you go for about 100HP over "stock" you'll probably be fine. But if your "stock" rebuild already includes a cam and some other high-HP stuff, I would limit the engine to about 600 ft-# or 550 HP. If you are already tearing up tires in 2nd gear, you might be near these numbers without the supercharger! What is your compression ratio? Have you dyno'd the motor? Do you have the M-22? -Bob Cunningham
Bob, Running an M-20 wide ratio, Hurst Comp Plus shifter, RAM Replacement Clutch, T/A Billet Flywheel. Stock compression 8.5 : 1 GM cast piston, C-M ring set Stock GM Stage 1 cam, installed straight up Tires are "stock" size & width, rather smooth at this time. Suggestions on parts combo???? Jim
Bob, Running an M-20 wide ratio, Hurst Comp Plus shifter, RAM Replacement Clutch, T/A Billet Flywheel. Stock compression 8.5 : 1 GM cast piston, C-M ring set Stock GM Stage 1 cam, installed straight up Tires are "stock" size & width, rather smooth at this time. Suggestions on parts combo???? Jim
Rule of thumb. 14 lbs of boost should double your HP so 7 lbs would give you @ 50% increase and so on. So 300HP + 7lbs of boost would be 450, 5 lbs would be 408 HP. With your combo, I wouldn't be worried about making too much if you keep the boost down. You have a mild enough of a combo, you won't get too wild with a little boost. :TU:
Fuel system for boost(boost referenced regulator) Blow thru holley or BG style carb B4B style intake supercharger kit
I'll have to let others say whether the M-20 can withstand the amount of power you want to make. I would guess that it cannot, but I am nowhere near an expert in that area. The supercharger can easily bring you into the high-HP arena, so frankly I'd be concerned about things holding together. Just a few PSI of boost would probably be great, but you might get more bang-for-the-buck out of other mods like cam, headwork, and so on. One thing for sure- with the supercharger cramming all that air into the motor, you'll need the headers to let the air out! You'll need a free-flowing exhaust for sure. -Bob C.
