C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1989 upgrades

Old Sep 12, 2022 | 10:03 PM
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Default 1989 upgrades

Just wondering about making some small upgrades to my stock 89 6 spd.
New injectors probably Bosch 3
Roller rockers 1.6
Exhaust manifolds shortie headers, or is there a stock Corvette exhaust manifold that will give me a little more power.
ECM? should I buy and aftermarket? Upgrade to a different year?

This car is rarely going over 4000 rpm.
Thank you
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Old Sep 12, 2022 | 10:44 PM
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- upgrade to a newer year is biggest bang for buck…if you want 300+ hp.

That said a nice easy upgrade for a stock L98 is a stock LT1 cat back exhaust. Cheap and easy, and should sound better too. Lots of people have them or are trying to dump them after upgrading exhaust. They flow very well.

After that I would think long tubes, cam and rollers would net you a decent gain. Some port the tpi… obviously these changes need a tune.

I wouldn’t just swap injectors to a higher flow…not unless other mods make it so you need them. That’s going to cause issues otherwise.

I also wouldn’t change the ECM…it can be tuned to match whatever changes you make.
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Old Sep 12, 2022 | 11:10 PM
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First. Thank you for the reply.
I thought long tube headers would be for higher RPM applications. Bigger injectors? 24 versus the stock 22s?
Thank you
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Old Sep 12, 2022 | 11:30 PM
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Curious, why do you not want to rev above 4K? That’s a lot of power band on the table?

What is your goal? Hp goal? Low end torque monster? Budget? What are you planning on doing with the car?
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Old Sep 13, 2022 | 03:24 AM
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Great question. What I mean about 4k is I am not looking to build a street racer. I don't get on the car often. That being said. I would like as much horsepower as I can get without new heads, rings, turbo charger, nitrous.
I had an 84. I ported the intake, a slightly higher profile cam and roller rockers.
I'm thinking something similar for this car. Good manners,. Some fuel economy and a tad more performance. I may take it to a road course once in awhile.
I hope this helps you help me. 😊
Thank you
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Old Sep 13, 2022 | 09:25 AM
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Depending on your local smog laws...

Long tube headers and a better flowing exhaust system is the place to start for most L98 guys.
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Old Sep 13, 2022 | 09:28 AM
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Thank you for the input. Long tube it is.
with respect to smog laws . Cars this old don't have to pass emissions testing,👍
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