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Drivability threshold when modifying an L98?

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Old Aug 6, 2007 | 11:08 PM
  #1  
CarolinaMTBguy's Avatar
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From: Rolla, MO
Car: '89 IROC-Z
Engine: 5.7 TPI
Transmission: 700R4
Drivability threshold when modifying an L98?

I've been hunting for a third gen equipped with a 350 TPI but haven't found the right one yet, so I'm left to imagine what I'll do when I get one. I want to get a feel for how extensively the car can be modified without exorbitantly sacrificing gas mileage or drivability and what kind of power I can expect. I know the L98 may not be the cheapest or shortest route to humiliate the nearest mustang, but I love the torque and the shape of the powerband. What are peoples experiences or suggestions with the everyday drivability of different setups? No power adders, I'm concerned with engine modifications. How crazy can I go before I start sacrificing?

Last edited by CarolinaMTBguy; Aug 6, 2007 at 11:11 PM. Reason: Mean what you say, say what you mean...
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Old Aug 7, 2007 | 12:03 AM
  #2  
Kevin91Z's Avatar
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From: Orange, SoCal
Car: 1990 Pontiac Trans Am
Engine: 355 TPI siamesed runners
Transmission: Tremec T56
Axle/Gears: 12-Bolt 3.73
Re: Drivability threshold when modifying an L98?

Practically any camshaft or cylinder head change is going to require a custom chip. I was able to use a ZZ4 camshaft and heads with the stock chip, but I have no idea how far off it was. That made 282 RWHP and 380 RWTQ thru a T5 and ran 13.23 @ 107.18 MPH. It also got about 25 MPG on the highway.

Last edited by Kevin91Z; Aug 8, 2007 at 12:27 AM.
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Old Aug 7, 2007 | 12:26 AM
  #3  
CarolinaMTBguy's Avatar
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Joined: Jul 2005
Posts: 17
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From: Rolla, MO
Car: '89 IROC-Z
Engine: 5.7 TPI
Transmission: 700R4
Re: Drivability threshold when modifying an L98?

Yeah, guess I should've mentioned something about a custom chip and a tune in the original post. Let's just assume an appropriate chip and tune is performed on the setup.......
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Old Aug 7, 2007 | 06:08 PM
  #4  
BMmonteSS's Avatar
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Joined: Feb 2002
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From: Buckhannon, WV
Car: 84' Monte
Engine: 350
Transmission: 700-r4
Axle/Gears: ferd 9" posi 3.50 gears
Re: Drivability threshold when modifying an L98?

Just to expand a bit, an "appropriate" tune is one that you do yourself with lots of datalogging and testing. Or you get done by some one with lots of experience with your car in hand. Mail order or telepathy chips as I call them won't cut it.

If you have complete control of the ecm you can run into the 12's and still break 20 mpg pretty easily.
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