Question: Supercharging a L98

[Corvette Emma]

I have a 1989 with the L98 motor. Can anybody tell me if the bottom end can handle supercharging and if so, how much boost. :confused

 

[6 Shooter]

CE - Ya might want to check with a few OEM's who have super-charged Vette engines.

Lingenfelter provide me with a quote earlier this year for my LS6...

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Later . . . . . .
6 Shooter

 

[boomdriver]

I would hesitate to add boost to a stock bottom end that had some miles on it....
even new, its a lot of additional stress on the stock rods and pistons.
For $2500 you can get a forged crank, some nice rods and pistons and start fresh with a reliable build.

Everyone that I know that has supercharged their vette, did so with a fresh block. I do know of one guy that runs Nitrous (a big dose) in his stock motor and does 1/4 runs all the time and so far has not had it self destruct. But again, he started with a fresh motor when he added the juice.

 

[Corvette Emma]

Plan B

I guess I will have to settle for a set of AFR Heads and a cam and hope AFR is close with their 80 added horsepower claim. Although my motor only has 20k miles on it so it might handle a low boost supercharger before exploding.
I'm so confused.
Lee

 

[93Rubie]

If you only put 5 to 6 psi to it I think it would be fine as long as you get it properly tuned and so forth. I would replace the head gaskets just due to age of them. Obviously with boost you need supporting modifications such as bigger injectors, tune, etc...

 

[Corvette Emma]

Head Work

If I pull the heads to replace the gaskets, are the stock heads worth machining? I am also wondering if I should go with 1.5 rockers?

 

[boomdriver]

If I pull the heads to replace the gaskets, are the stock heads worth machining? I am also wondering if I should go with 1.5 rockers?

The stock heads can be ported and upgraded, but not to the extent that they'll compare to these super flowing after market heads. Those L98 heads were designed 30 yrs ago...many things have changed since then.
If you;re adding a charger the heads become less of an issue. Heads are the issue with a naturally aspirated engine. And 1.6:1 ratio rockers for the intake...YES. Full rollers. 1.5 for the exhaust seems to work for many folks.

20K miles...? I'd feel safe about a 6 lb charger. That engine is still "fresh" mechanically. Gaskets and seals are the only real question and thats only from age. Time does as much damage as actual use or abuse.
Many of the kits available are as simple as the pulley size to limit the amount of boost thats available.

Just remember, as 93Rubie says, when adding a charger, thats just the beginning. There will be fuel injectors, and a complete retune after that. There will be "expenses" in making it right. That ECM tries to create a 14.7:1 air/fuel ratio at all times....so when you add massive amounts of air, the fuel has to be available as well. If not, it ain;t gonna run right, if at all.

Thats what makes Nitrous attractive...much more of a "bolt-on" HP gain. Cheaper, too.

 

[93Rubie]

Cost is the reason I am not going the turbo/supercharger route. I can get the HP I want out of my stock LT1 block. Ported and Polished Heads, Cam, etc, etc...seem to be for me the most cost effective way. Nitrous can be very good too if done right. Progressive controllers and wet systems and such. "In Case of Turbo, Push Button." I have seen that a good blower system to be priced new to be in the 4-6K range. Used I have seen them cheaper, but again fuel, ignition, and then tuning add up. Then again everything is better when its "blown."