113 vette heads--how much gain?
12-24-2009, 02:49 PM
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Car: 1991 Trans Am GTA
Engine: L98(5.7 L TPI)
Transmission: 700r4(A4)
Axle/Gears: G80 RPO, 3:23s, Auburn Racer's Diff
113 vette heads--how much gain?
If i slap some 113 vette heads on my 1991 350 TPI, how much HP gain should I see (with no porting, other work, etc.)
Is it a direct bolt on?
Before installing the heads, what should be done? (New springs, roller rockers, bolts, etc?) How much will all that extra stuff cost?
Am I better off going with aftermarket heads instead?
Is it a direct bolt on?
Before installing the heads, what should be done? (New springs, roller rockers, bolts, etc?) How much will all that extra stuff cost?
Am I better off going with aftermarket heads instead?
12-24-2009, 05:36 PM
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Car: 1996 Vette / 1992 GSX1100F Suzuki
Engine: 1996 Corvette Coupe 388 LT1 (+.060)
Transmission: Auto
Axle/Gears: 3.07
Re: 113 vette heads--how much gain?
You'd be much better off with a pair of after-market heads. Swapping from what you now have to 113s wouldn't be getting the most BANG FOR THE BUCK. Once you factor in all the machine work and parts a set of used 113s will probably need, the cost difference (if any) wouldn't be all that much.
Many of the aftermarket heads can be bought with the valves, springs, retainers, new valve job, etc. that you'd need already installed and ready to bolt on.
You can always use GOOGLE, or some other Search Engine, to track down the flow numbers of the stock 113s and compare them to after-market offerings. In most cases you'll see a BIG difference.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
Many of the aftermarket heads can be bought with the valves, springs, retainers, new valve job, etc. that you'd need already installed and ready to bolt on.
You can always use GOOGLE, or some other Search Engine, to track down the flow numbers of the stock 113s and compare them to after-market offerings. In most cases you'll see a BIG difference.
Jake
West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!
12-24-2009, 07:53 PM
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Re: 113 vette heads--how much gain?
The aluminum Vette heads really didn't flow any better than their cast iron L98 cousins. The smaller chambers will bump up compression a bit, but in a 91 L98 you are already close to 10:1, despite what official factory specs say (somewhere around 90-91 they switched from dished pistons to flattops in the L98- as verified by many members of this board who have taken their original engines apart).
I agree, it's not worth the swap. Not only will there be very little power gain, but your EGR system won't work any more (113 heads don't have exhaust crossover passages). And the intake bolt pattern isn't the same as your 87-up heads (Vette/113 heads use the earlier 86-down intake bolt pattern).
Look to the aftermarket if you're going to do a head swap on that engine, would be my advice.
I agree, it's not worth the swap. Not only will there be very little power gain, but your EGR system won't work any more (113 heads don't have exhaust crossover passages). And the intake bolt pattern isn't the same as your 87-up heads (Vette/113 heads use the earlier 86-down intake bolt pattern).
Look to the aftermarket if you're going to do a head swap on that engine, would be my advice.
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