Mystery L98 combo
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Joined: Nov 2003
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From: EC, WI
Car: 1988 IROC
Engine: 350 TPI
Transmission: 700 R4
Axle/Gears: 2.77
Mystery L98 combo
Just purchased an 88 IROC with 'mild' cam, head work, headers, hypertech chip, air foil, .30 over rebuild (7,000 miles). The guy I bought it from said he didn't know the cam specs and the guy who had it built and the shop don't know and can't find paperwork. He said it dynoed at 310 HP but it only ran 14.9, a few tenths faster than my stock 89. I have many questions.
-Would a custom chip be better?
-The converter is stock and 2.77 gears, do I need to change them?
-The fuel pressure is low at 39 psi at idle, what should I set it at with the mods listed?
-Can I bump timing with chip, it is set at 6 right now
I know this is a shot in the dark with no engine specs, any ideas to make it run like it should would help. Thanks.
-Would a custom chip be better?
-The converter is stock and 2.77 gears, do I need to change them?
-The fuel pressure is low at 39 psi at idle, what should I set it at with the mods listed?
-Can I bump timing with chip, it is set at 6 right now
I know this is a shot in the dark with no engine specs, any ideas to make it run like it should would help. Thanks.
Joined: Sep 2005
Posts: 28,052
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Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
You didn't list any real "mods", except for the headers. All the rest of that is either of no consequence or it's too vague to even talk about.
In the absence of knowing what's actually inside the engine:
You should set the fuel pressure to wherever it runs the best.
You should set the timing to where it runs the best.
No telling about the chip, as that depends strongly on the cam that was used.
Yes you need to change the converter and gears; even with a totally box-stock car, those can be improved on.
Take the car to a chassis dyno place and pay somebody that knows what they're doing for some tuning. In addition to maybe unlocking some hidden power, you'll learn ALOT about the car; like, what RPMs does it make power at (which will in turn tell you what converter and gears would be best), what RPMs does it NOT make power at (avoid forcing it to run there), how much effect changing the fuel and timing has on power output, and so forth. When you don't know what you've got, there's no substitute for measuring it.
In the absence of knowing what's actually inside the engine:
You should set the fuel pressure to wherever it runs the best.
You should set the timing to where it runs the best.
No telling about the chip, as that depends strongly on the cam that was used.
Yes you need to change the converter and gears; even with a totally box-stock car, those can be improved on.
Take the car to a chassis dyno place and pay somebody that knows what they're doing for some tuning. In addition to maybe unlocking some hidden power, you'll learn ALOT about the car; like, what RPMs does it make power at (which will in turn tell you what converter and gears would be best), what RPMs does it NOT make power at (avoid forcing it to run there), how much effect changing the fuel and timing has on power output, and so forth. When you don't know what you've got, there's no substitute for measuring it.
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Joined: Sep 2000
Posts: 1,940
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From: Glendale, AZ
Car: 4 Mopars total
Engine: Pentastar power
Transmission: T/F and New Process
Axle/Gears: Three 8 3/4's & one 9 1/4
Ok, it ran a 14.9? What were the 60' times, the MPH, 330', 660'? I dont believe anything without seeing it on paper. The gears absolutely suck, the converter sucks. You need to list more info. Also, as far a a PROM is concerned...go with an actual custom PROM. Dont get any of that useless aftermarket garbage from Hypertech or Jet or any of that other crap.
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