HP on a roots-blown carbed Vette L98
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From: Missouri
Car: 1989 IROC
Engine: LB9
Transmission: T5
Axle/Gears: 3.42 Posi
HP on a roots-blown carbed Vette L98
I'm thinkin about a Vette L98 (aluminum heads 
) for my Cutlass, as the it's current 350 is in pretty rough shape. I'd be slappin a quadrajet carb. on it, along with my current headers and true duals system, and I was wondering how much power I'm looking at with this setup:
Vette L98 ('86, so cam specs are like 206 duration and .404 lift)
Headers/True duals
Wieand 144
1.6 ratio roller rockers
Rebuilt/Rejetted Quadrajet
MSD ignition setup
I assume I'd need to rejet the Quadrajet, and also pick up a new fuel pump, as I don't think the factory could handle the needed fuel flow.
Would expecting 350 hp at the crank be unreasonable?
) for my Cutlass, as the it's current 350 is in pretty rough shape. I'd be slappin a quadrajet carb. on it, along with my current headers and true duals system, and I was wondering how much power I'm looking at with this setup:Vette L98 ('86, so cam specs are like 206 duration and .404 lift)
Headers/True duals
Wieand 144
1.6 ratio roller rockers
Rebuilt/Rejetted Quadrajet
MSD ignition setup
I assume I'd need to rejet the Quadrajet, and also pick up a new fuel pump, as I don't think the factory could handle the needed fuel flow.
Would expecting 350 hp at the crank be unreasonable?
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Joined: Dec 2002
Posts: 531
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From: BC Canada
Car: 81Malibu
Engine: SBC 355
Transmission: TH400
Re: HP on a roots-blown carbed Vette L98
Originally posted by 80smetalfan
Would expecting 350 hp at the crank be unreasonable?
Would expecting 350 hp at the crank be unreasonable?
I'd get a book on tuneing that Q-jet though
Last edited by sleepybu; Jan 7, 2006 at 09:54 PM.
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Joined: Sep 1999
Posts: 7,072
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From: Philly, PA
Watch your compression ratio with a roots blower. I'm now on my 4th itteration of my roots-blown 383. It's been a little painful as I have a hard time getting it drilled into my head that 9:1 compression is TOO MUCH with a roots blower and pump gas!
My last engine with the Weiand 142 made 390HP to the rear wheels (420 torque as low as I could lug it) with 26* of spark advance, 8.7 compression, AFR aluminum heads and a modest cam. A few months back I turned the timing up to 28* and promply blew it to smithereens after 2 years of faithful service running at 26*. REAL touchy!
I've finally learned my lesson- I'm absolutely TANKING the compression on the 4th version of this motor: 8:1, no other changes to the combo. I should lose NOTHIG to the compression drop. I had to keep the timing so modest with the last combo I'm sure I was leaving a lot on the table. With this combo I should be able to run 28-30* safely on pump gas and make back what I lost by dropping the compression.
350 ponies at the flywheel? Like falling off a log if you don't blow it up from detonation.
BTW- I run a QJet on top of my blower, too. Tuned by yours truly.
My last engine with the Weiand 142 made 390HP to the rear wheels (420 torque as low as I could lug it) with 26* of spark advance, 8.7 compression, AFR aluminum heads and a modest cam. A few months back I turned the timing up to 28* and promply blew it to smithereens after 2 years of faithful service running at 26*. REAL touchy!
I've finally learned my lesson- I'm absolutely TANKING the compression on the 4th version of this motor: 8:1, no other changes to the combo. I should lose NOTHIG to the compression drop. I had to keep the timing so modest with the last combo I'm sure I was leaving a lot on the table. With this combo I should be able to run 28-30* safely on pump gas and make back what I lost by dropping the compression.
350 ponies at the flywheel? Like falling off a log if you don't blow it up from detonation.
BTW- I run a QJet on top of my blower, too. Tuned by yours truly.
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