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

L98 guys...

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Old Mar 19, 2003 | 04:31 PM
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Default L98 guys...

I have a few questions for the L98 guys (and gals).

What's your best quarter mile time? What's the best quarter mile time ever posted by a normal tuner with an L98? In what order should I start doing modifications?
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Old Mar 19, 2003 | 05:57 PM
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Default Re: L98 guys... (Feenix566)

The best 1/4 mile time for a 100% stock L98 is ~13.8

I notice in your signature that you have run a 14.5@93mph. If you ran 93mph at a NJ track I would say that your engine isn't 100% in tune. It should be 96-98 depend on if you have an auto or standard.
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Old Mar 19, 2003 | 06:13 PM
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Default Re: L98 guys... (Feenix566)

All the info is in my sig. I did a 13.6 something with only a k&n airfilter.

I added cut box, removed frisbee, air pump eliminator kit, hedman 1 5/8" headers, true dual 2.5" exhaust without cats (now running 3" dual with h-pipe because of poor fitting 2.5" system), throttle body bypass. I think that's all, I dyno'd at 254rwhp and 354rwtq. I haven't been back to the track because of a slipping clutch, but I picked up about 30+rwhp, so I expect to run 13.3's

The track is at sea level, or below. Times are probably consistant with Englishtown, but E-town is most definately better prepped.

I plan to fully port my intake in the next month while I fix the leak.

Edit: changed gain of 40rwhp to more realistic 30+rwhp


[Modified by Raistlin, 6:23 PM 3/19/2003]
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Old Mar 19, 2003 | 06:21 PM
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Default Re: L98 guys... (Raistlin)

Best time along with mods are in signature
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Old Mar 19, 2003 | 07:02 PM
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Default Re: L98 guys... (Feenix566)

This is what i'm doing:
Catback exhaust, hi-flow cat, headers
then intake mods (superram, AFR 190 heads/ accel 219 cam)
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Old Mar 19, 2003 | 07:07 PM
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Default Re: L98 guys... (vader86)

I did 13.9 with the listed mods in the sig !!
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Old Mar 19, 2003 | 08:00 PM
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Default Re: L98 guys... (Raistlin)

OK, I figured I'd pick this up sooner or later, but I'm getting sick of waiting :bb . Whats a frisbee :confused: ? And while I'm at it I'll get this out of the way, my air filter lid is louvered with like eight good size louvers. Is this stock, and if so, what exactly do you gain by cutting the lid :banghead: ? Thanks everyone :auto:
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Old Mar 19, 2003 | 08:10 PM
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Default L98 guys...

Back when my car was stock(and I was still sane) it did a 13.98@98.X COMPLETELY stock. Just the way I bought it from the previous owner. No timing changes,filter etc. 1990 Car.

LOL I honestly wish it still we're stock on some days. A LOT less headaches. :yesnod:

Talk to chucks88, 65z01 and Vic'89.(To name a few) they all have quick L98's with minimal mods and they go like hell for the money they have invested.


[Modified by JD 90 383, 8:11 PM 3/19/2003]
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Old Mar 19, 2003 | 08:11 PM
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Default Re: L98 guys... (Feenix566)

see my sig for the mods i did and the times i got from them.
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Old Mar 19, 2003 | 08:11 PM
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Default Re: L98 guys... (86Moon)

Hey Vader, What do you expect to run with those mods? I want to do them as well plus an engine rebuild. Too many miles.

Cut lid cuts a bigger area in the air filter cover, 3-5 hp
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Old Mar 19, 2003 | 08:27 PM
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Default Re: L98 guys... (86Moon)

OK, I figured I'd pick this up sooner or later, but I'm getting sick of waiting :bb . Whats a frisbee :confused: ? And while I'm at it I'll get this out of the way, my air filter lid is louvered with like eight good size louvers. Is this stock, and if so, what exactly do you gain by cutting the lid :banghead: ? Thanks everyone :auto:
The frisbee is a metal disk, attached to the water pump pully with 4 bolts. It's about 10" in diameter (from memory) and was used to dampen vibration from the ac cycleing on and off. It's simple to remove, take the 4 bolts out, remove the disc, replace the bolts. I used some washers about the same thickness as the disc so the bolts wouldn't bottom out, some people haven't.

My air box had those same louvers, I just cut the louvers out instead of cutting the box out to the edges. The theroy is you'll get more airflow with a larger hole, plus you use more of the filter surface.
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Old Mar 19, 2003 | 11:29 PM
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Default Re: L98 guys... (Raistlin)

Stock auto wth 2.59's. Removed air lid, no pre-cats=13.9@101

Hooker Sc's, dual exhaust, 3.07 gears, 2,600 stall converter,drag radials,free mods= 13.2@102.


[Modified by Fastguy, 11:30 PM 3/19/2003]
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Old Mar 20, 2003 | 12:37 AM
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Default Re: L98 guys... (Raistlin)

Thanks Raistlin
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Old Mar 20, 2003 | 02:06 AM
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Default Re: L98 guys... (Feenix566)

I baselined my '88 in Aug. '00 at Raceway Park to the tune of 14.4sec @94mph (14.0sec @95mph corrected for weather); my current best numbers are in my sig.

For some simple initial mods:
-toss the "frisbee"-10hp
-install a 160deg stat & fan sw-10hp
-cut back the spark plug ground electrodes-10hp
-install a K&N air filter with a cut lid-10 to 15hp

When you get some real $$ up install a hi-flow cat & good cat-back. Either do ceramic coated LT headers or 2 1/2" front Y w/o pre-cats.

If you have an A4 install a TransGo shift kit and, for street use, a 2,000rpm TC.

If you want a nice recipe for over 350hp at the crank, drop me an e-mail.




[Modified by 65Z01, 1:08 AM 3/20/2003]
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Old Mar 20, 2003 | 07:39 AM
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Default Re: L98 guys...

I went 13.87 bone stock at 98mph.

You seem to be down some mph, could be a clogged cat.

Vic
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Old Mar 20, 2003 | 07:58 AM
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Default Re: L98 guys... (86Moon)

Thanks Raistlin
:thumbs: :flag
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Old Mar 20, 2003 | 01:10 PM
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Default Re: L98 guys... (Raistlin)

here's my "mods":

K&N air filter in stock air box
air foil
Flowmasters & catback y-pipe
removed frisbee
160 degree thermostat

also, it's a four-speed automatic and it has 101k miles on it.

how would i clean out a clogged cat? if that's not it, how should i go about tuning it?


[Modified by Feenix566, 1:14 PM 3/20/2003]
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Old Mar 20, 2003 | 01:16 PM
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Default Re: L98 guys... (Feenix566)

how would i clean out a clogged cat? if that's not it, how should i go about tuning it?
Buy a new Cat.

Vic
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Old Mar 20, 2003 | 01:28 PM
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Default Re: L98 guys... (Feenix566)

how would i clean out a clogged cat? if that's not it, how should i go about tuning it?
Broomstick.
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Old Mar 20, 2003 | 04:12 PM
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Default Re: L98 guys... (Jim85IROC)

13.8@97mph. Off the line it was a rocket. But the engine felt like it was hitting a brick wall at the upper rpms', not the same feeling as hitting 4,800 rpm though. Think my cats had something to do with it since a few months later the two pre-cats clogged the main cat so bad the car would barely run.
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