At the track saturday. I need some mods.

[tooez]

Well went to the track saturday to see what bone stock 1990 L98 auto would do. I have never been to a drag strip. We only have a 1/8 mile track around here.This was my best time.
.7530---reaction
1.9859---60 ft
5.8317---330 ft
8.4400---594 ft
9.0391---1/8
75.12---mph
My slowest time was a 9.28

I would like to break into mid 8's. I have read that the problem with the L98 is not getting enough air. So what some choices. Can I just get a bigger plenum and runners or do I need intake and all. Will this give me a little more. I know that I can get the heads ported and that will give me some. But I really don't want to do the heads until I do the complete engine. What kind of runners and where can I get them. I did a search. But came up empty. Thanks for any input.

 

[Moonunit 451]

Have you done the "free mods"? Next, it's exhaust, cats and headers. some folks will change out the stock rear gears to get quicker. Next, there are some porting and polishing you can do on the plenum, runners and intake.

Search MadMic's posts, you'll find similar but more specific advice. Also search for "free mods"

 

[Vettefan87]

The fastest my car turned the 1/8 mile was 8.91 @ 79.35 mph that was with a 2.0 60 ft time. I have done all the free mods, plus Headers, Ram Air, TB airfoil, and Hypertech Thermo master chip. Once you start the mods you will never stop, or at least wont ever want to.

 

[tooez]

I have read all about free mods. I will do them this week. I don't want to get bashed for this. But I got new exhaust on the car. No headers yet but I am running straight pipes from the manifolds to the mufflers. I will be checking into some 373 gears next and having the plenum, runners and intake ported and polished. I was thinking maybe a bigger or better plenum, runners and intake. thanks for the info.

 

[WhalePirot]

No bashing Zone, this CAC

It's now quite so simple, but with patience and a LOT of searching and reading here, and elsewhere, you will avoid the disasters of a few members, and the problems many of us have caused ourselves as we learned.

MadMic has a great family racing background and has documented many of his stepwise mods.

BTW, the '90 is a speed density system, which is less tolerant of mods than the MAF system is.

 

[Hrtbeat1]

What kind of gearing do you have now? You can look in the center console on the lid there should be a RPO list, on that look for GM1, or something like that.


1.98 second 60' time isn't too bad you can get that down some by working on your reaction time (.753 is a little long) Im guessing they use a .500 tree.

As far as runners there are a couple of places that sell them. Lingenfelter in Indiana www.lingenfelter.com ; TPIS in Minnesota www.tpis.com ; SLP in New Jersey www.slponline.com ; or Arizona Speed and Marine in Arizona www.azspeed-marine.com ; and Street and Performance also in AZ www.hotrodlane.cc are a few that come to mind. I think Edelbrock is the actually the foundry for the TPIS big mouth manifold but I'm not sure.

 

[C4Tom]

Did you notice wheel spin off the line? Make sure you are hooking up, that will kill your 60 foot times. I hear L98 owners talk about the big torque they make, so traction is paramount. A 1.98 sec 60' is respectable.

Getting a motor to breathe concerns both taking in air and getting it out, so you may need to check exhaust system as well. Clogged cats? Pipe diameter? You've mentioned the intake and that may not be your main concern.

Make sure you are using good premium fuel and add an octane booster. The spark control can add more timing sooner if the octane level is higher. You should run a tank full of gas with Chevron Techron through it first to get the injectors clean if it's been a while.

Good luck,

 

[tooez]

1.98 second 60' time isn't too bad you can get that down some by working on your reaction time (.753 is a little long) Im guessing they use a .500 tree.

Yes they are using a .500 tree. I have never been to a drag strip or never even seen one. I will be working on the reation time.

What kind of gearing do you have now? You can look in the center console on the lid there should be a RPO list, on that look for GM1, or something like that.

I'm running 3.07 gear. I'm going to check into some 3.73.

Did you notice wheel spin off the line? Make sure you are hooking up, that will kill your 60 foot times. I hear L98 owners talk about the big torque they make, so traction is paramount. A 1.98 sec 60' is respectable.

I'm hooking up good with not a lot of wheel spin.

Getting a motor to breathe concerns both taking in air and getting it out, so you may need to check exhaust system as well. Clogged cats? Pipe diameter? You've mentioned the intake and that may not be your main concern.

I still have the stock manifolds. But my exhaust was shot. I had a problem with the car running super rich. Which did clog the cats. So they were removed. So the muffler shop ran 2 1/2 straight pipe from the manifold to the mufflers. I'm going back to have a H pipe put in.

I will do the freemods this week. When I bought the car in feb. it didn't run that good. I have got it to run perfect. The car got about 140000 on it so I just want to do some mods to get a little better. This winter I will be rebuilding the motor. But I want to enjoy my first vette for the summer. then do the motor. Plus it gives me time to buy all the parts and have them all ready for winter. Less down time. I have read alot of mad mic's post.

one last thing. What size tires are people running for the track. Does some one know if I can put some 15 inch cheater slicks on or do they need to be bigger rim.

And I want to thank you all for repling to my thread. Someday I will have the knowledge to help others. Thanks.

 

[C4Tom]

Yes they are using a .500 tree. I have never been to a drag strip or never even seen one. I will be working on the reation time.

Leave on the last yellow.

I'm running 3.07 gear. I'm going to check into some 3.73.

Raising the gear will make it launch harder and cut your times. Harder launches will require a wider, stickier tire, so keep that in mind too.

I still have the stock manifolds. But my exhaust was shot. I had a problem with the car running super rich. Which did clog the cats. So they were removed. So the muffler shop ran 2 1/2 straight pipe from the manifold to the mufflers. I'm going back to have a H pipe put in.

Use the intake manifold money instead to get some headers on it. You'll find that to be your best gain right now.

I will do the freemods this week. When I bought the car in feb. it didn't run that good. I have got it to run perfect. The car got about 140000 on it so I just want to do some mods to get a little better. This winter I will be rebuilding the motor. But I want to enjoy my first vette for the summer. then do the motor. Plus it gives me time to buy all the parts and have them all ready for winter. Less down time. I have read alot of mad mic's post.

Mad Mic knows his $h1t! Listen to him.

What size tires are people running for the track. Does some one know if I can put some 15 inch cheater slicks on or do they need to be bigger rim.

I use 275/40ZR18 Goodyear F1 runflats on Y2K Vette rims(18x10) on the back. Spinning them out 20-30 feet and getting a 1.97 sec 60' time. With my short gear I ran 9.0 1/8 mile and 13.98 1/4 mile. I'm getting some sticker tires soon and that should get my times down quite a bit.

 

[Vettelt193]

In my experience stock or near stock L98's tend to be good 1/8 mile runners, especially the automatics.

definitely do the free stuff first... open the air-box lid etc., then do exhaust (it's pretty restrictive on the L98)

other good L98 Mods, IMHO, are full roller rockers and big intake runners.

I've got no experience with stock L98's and gear changes. I am doubtful that they will help much because of the engine's power-band. I think the low gears could actually hurt some just because you will blow through the peak power range so fast.

 

[Vettefan87]

I would not worry so much about reaction time. The time should not start until you move. Reaction time is only used during brackets and what not. At my local strip Friday nights is like a Test and Tune, pay 20 bucks and you can run from 4:30 till dark, but on Sunday there are brackets and the fun stuff.

I agree on the headers you don't want to mod your car backazzwards. Get it breathing better, then port the plenum, and buy a new intake.

 

[Edmond]

The L98 intake was originally designed for the 305 motor. What I would do is get some large tube runners, port the plenum and port the intake. 1.6 roller rockers would also be nice since you'll be working in that area. I think Mad Mic said you can see 20 hp with headers over the exhaust manifolds, probably save some weight as well.

The stock mufflers on the L98 only flow through one outlet on each muffler. An aftermarket performance such as Flowmaster or Magnaflow will get you much more than the stock system as they flow through both outlets on each muffler.

 

[Mad-Mic]

i've been a 8.24 at almost 86 mph so far with a handfull of bolt on's

 

[Vettefan87]

i've been a 8.24 at almost 86 mph so far with a handfull of bolt on's

I hate you :L. So if I pay to fly you out to South Bend, will you tweak my vette for me?

 

[Mad-Mic]

I hate you :L. So if I pay to fly you out to South Bend, will you tweak my vette for me?

sure

 

[max]

C4Tom' s Quote :Lleave on the last yellow.
As much as I seen it , better to leave a fraction before third yellow flicks on . Then you can get 0.600 on a 0.500 tree

 

[Mad-Mic]

C4Tom' s Quote :Lleave on the last yellow.
As much as I seen it , better to leave a fraction before third yellow flicks on . Then you can get 0.600 on a 0.500 tree

every car is differnt. it's called Roll Out. weight, trans gear ratio, rear gear ratio, torque, tire size and width all play a part in where your sweet spot is.

all Roll Out is, is how quick the tire gets out of the beam to trip the timers.

mines a fraction past the last yellow coming on and i average .550 lights

 

[C4Tom]

every car is differnt. it's called Roll Out. weight, trans gear ratio, rear gear ratio, torque, tire size and width all play a part in where your sweet spot is.

all Roll Out is, is how quick the tire gets out of the beam to trip the timers.

mines a fraction past the last yellow coming on and i average .550 lights

And... don't forget... deep or shallow staging.

I just tickle the beam... then go on the bottom yellow. It's a bit different with my Malibu.