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

L98 build up

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Old 08-21-2008, 09:11 PM
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snowmanmdp
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Default L98 build up

O.K. here is my plan for my 85 L98...

1985 Corvette
· 5.7L V-8 L98
230 HP @ 4000 RPM
330 lb-ft @ 3200 RPM
· 0-60 in 5.7 sec
· Quarter Mile in 14.4
Under drive pulleys: +8-11 HP
Vortec heads: 12558060, +40-50 HP
Long tube headers +20-30 HP
Throttle body airfoil: +3-5 HP
Vortec Intake: 12498060, +20-25 HP
Roller Rockers: 12-18 HP
52mm throttle body: +6-8 HP
Large tube runners: +10 HP
Ported Plenum: +10-15 HP
Ported Mass air sensor: +5-10 HP
If you did it all you would have similar power to a ’96 LT4 Corvette and it should be able to run low 13’s.

Well any thoughts?
Old 08-21-2008, 09:20 PM
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vader86
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Under drive pulleys: +8-11 HP -reasonable
Vortec heads: 12558060, +40-50 HP -not if you dont change the cam
Long tube headers +20-30 HP -only get that much from doing the whole exhaust
Throttle body airfoil: +3-5 HP -very funny
Roller Rockers: 12-18 HP -15 is reasonable

Vortec Intake: 12498060, +20-25 HP -
52mm throttle body: +6-8 HP -nope
Large tube runners: +10 HP
Ported Plenum: +10-15 HP

You may not get 30 from doing the whole intake, much less these numbers on individual parts.

Ported Mass air sensor: +5-10 HP -very funny
Old 08-21-2008, 09:25 PM
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cwyates4
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heads and intake are good mods, but a cam is needed to get their full potential.

I've got a ported/powdercoated plenum I'll sell you.
Old 08-21-2008, 10:55 PM
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CorvetteMike2024
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I'll take the LT4. How much does all these mods cost?
Old 08-22-2008, 12:00 AM
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CJWC4AZ
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Default Want to feel a difference?

The best upgrades to my '90/Auto was a Pete Kane rebuilt trans, 2600 TC and 3:73 gears. Will feel like you picked up 50 HP and nobody will beat you off a light. I mean off the starting line at the track. If yours is a daily driver go with 3:07's. Thank you Pete!
Old 08-22-2008, 12:54 AM
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corvettedan22
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I would jump into all thoose mods, with the cam, but im way past the tunning and trying to get a car to run right.
Old 08-22-2008, 05:47 AM
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snowmanmdp
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Originally Posted by CorvetteMike2004
I'll take the LT4. How much does all these mods cost?
About $1,800 with the G.M. discount
Old 08-22-2008, 05:50 AM
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snowmanmdp
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[IMG][/IMG]
Originally Posted by cwyates4


heads and intake are good mods, but a cam is needed to get their full potential.

I've got a ported/powdercoated plenum I'll sell you.


Sorry already have one
Old 08-22-2008, 08:32 AM
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Iroc57
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You can't just add the "advertised" gains from each and expect to have that power total. If you get it to breath it will make power so you are on the right track. Tap some experience here and find out what heads/cam/intake are making the best power, throw headers and a decent exhaust on there and go. The trial and error have been done by many on here for you already.
My advice is to take the money you would spend on the pulleys and airfoil and have a nice fancy dinner. You will get more for your money that way
Old 08-22-2008, 09:55 AM
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snowmanmdp
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Originally Posted by Iroc57
You can't just add the "advertised" gains from each and expect to have that power total. If you get it to breath it will make power so you are on the right track. Tap some experience here and find out what heads/cam/intake are making the best power, throw headers and a decent exhaust on there and go. The trial and error have been done by many on here for you already.
My advice is to take the money you would spend on the pulleys and airfoil and have a nice fancy dinner. You will get more for your money that way
Not saying that I will...The air foil and pulleys are already on the car from the previous owner. As for experience on the weekend we 6.00 @ 220 mph so I think we might have an idea? We will be at Norwalk today and Saturday for the ADRL Pro mod outlaw race.
Old 08-22-2008, 10:08 AM
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Originally Posted by CJWC4AZ
The best upgrades to my '90/Auto was a Pete Kane rebuilt trans, 2600 TC and 3:73 gears. Will feel like you picked up 50 HP and nobody will beat you off a light. I mean off the starting line at the track. If yours is a daily driver go with 3:07's. Thank you Pete!
What did you feel ?
Old 08-22-2008, 10:30 AM
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Iroc57
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Originally Posted by snowmanmdp
Not saying that I will...The air foil and pulleys are already on the car from the previous owner. As for experience on the weekend we 6.00 @ 220 mph so I think we might have an idea? We will be at Norwalk today and Saturday for the ADRL Pro mod outlaw race.
Sorry...didn't mean to offend. I didn't expect someone with your experience to list modifications with horsepower numbers like that. You still may be able to learn something from the corvette gurus here they have used many of the combos you will look at.
Old 08-22-2008, 10:50 AM
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Originally Posted by snowmanmdp
O.K. here is my plan for my 85 L98...

1985 Corvette
· 5.7L V-8 L98
230 HP @ 4000 RPM
330 lb-ft @ 3200 RPM
· 0-60 in 5.7 sec
· Quarter Mile in 14.4
Under drive pulleys: +8-11 HP
Vortec heads: 12558060, +40-50 HP
Long tube headers +20-30 HP
Throttle body airfoil: +3-5 HP
Vortec Intake: 12498060, +20-25 HP
Roller Rockers: 12-18 HP
52mm throttle body: +6-8 HP
Large tube runners: +10 HP
Ported Plenum: +10-15 HP
Ported Mass air sensor: +5-10 HP
If you did it all you would have similar power to a ’96 LT4 Corvette and it should be able to run low 13’s.

Well any thoughts?
You will need a good cam and tune to make this work. Put the throttle body and the airfoil money into a cam. Put the pulley money into an electric water pump.
Old 08-22-2008, 11:08 AM
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janarvae
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Originally Posted by snowmanmdp
[IMG][/IMG]



Sorry already have one
I'd never considered powdercoating my runners and TB, but I like that color combination. Do you have any more pictures?

Jonathan
Old 08-22-2008, 11:12 AM
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formul89
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Keep the long tube runner set up and it will make a mountain of delicious low end torque, but not much horsepower with those mods.

Which is perfect for the street.
Old 08-22-2008, 12:05 PM
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I'm with vader on this one, half of the listed things won't give nearly as much as you expect. You'd be better off porting the intake you have, getting bigger runners first of course, then porting the heads, getting a nice cam, and work with exhaust and gears.

What exactly is your goal? You want to outrun an LT4? Drag radials and a 3500 stall converter(auto) would beat it in the 1/8 mile. SR intake with a higher lift cam and full dual exhaust with LTs would take it in the 1/4. You do know these cars are made for more than straight-line, right?
Old 08-22-2008, 12:07 PM
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snowmanmdp
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Originally Posted by formul89
Keep the long tube runner set up and it will make a mountain of delicious low end torque, but not much horsepower with those mods.

Which is perfect for the street.
Finally...someone gets it I have not be offended and I don't mind hearing others input at all! What I'am trying to do is build a 350 horsepower car Nothing more nothing less I DO NOT WANT SOMETHING THAT EVERYTIME I TAKE IT OUT I NEED TO BE TURNING WRENCHES!!!! I just don't want a 230 horsepower turd So feel free to keep posting

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Old 08-22-2008, 01:43 PM
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cplonner
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Everything you said but I have a little bit of a bigger than stock cam.
I do not have an airfoil, my throttle body is stock and my mass air sensor is stock.

The higher hp run is with a better tune.
Old 08-22-2008, 04:53 PM
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black85
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You don't need all that stuff to run low 13's. My 85 ran a 13.7 the first time out, and all it had was the cat removed, a k&n airfilter, cut airbox lid, and the 2.5" Borla catback. I added TPIS headers and it ran a 13.3. I more recently put on underdrive pulleys and the airpump delete and it still runs a 13.3, just with more tire spin. I think it needs more traction at this point. I never shifted the car, just floored it in Drive. And this is with 2:73 gears. They match the TPI setup well b/c otherwise you would really blow the tires off the thing. This is also leaving at idle, b/c it spins too much if you get up on the converter.

I did do a few little things that aren't supposed to make much difference like the updated ESC, a tune up, airfoil, IAT relocate, power coupler (instead of accordian tube coupler), ported plenum (well, maybe that one does something), and afpr. I bet I could take half that stuff off and it would stilll run a 13.3. I should have listed the k&n down here with stuff that isn't supposed to do anything. Also, I ran Amsoil in engine, trans and rear.

This chart is prior to the underdrive pulleys and maybe airpump delete, but I forget if that was the case.




Last edited by black85; 08-22-2008 at 05:05 PM.
Old 08-22-2008, 07:33 PM
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Originally Posted by black85
You don't need all that stuff to run low 13's. My 85 ran a 13.7 the first time out, and all it had was the cat removed, a k&n airfilter, cut airbox lid, and the 2.5" Borla catback. I added TPIS headers and it ran a 13.3. I more recently put on underdrive pulleys and the airpump delete and it still runs a 13.3, just with more tire spin. I think it needs more traction at this point. I never shifted the car, just floored it in Drive. And this is with 2:73 gears. They match the TPI setup well b/c otherwise you would really blow the tires off the thing. This is also leaving at idle, b/c it spins too much if you get up on the converter.

I did do a few little things that aren't supposed to make much difference like the updated ESC, a tune up, airfoil, IAT relocate, power coupler (instead of accordian tube coupler), ported plenum (well, maybe that one does something), and afpr. I bet I could take half that stuff off and it would stilll run a 13.3. I should have listed the k&n down here with stuff that isn't supposed to do anything. Also, I ran Amsoil in engine, trans and rear.

This chart is prior to the underdrive pulleys and maybe airpump delete, but I forget if that was the case.



The car already has all of that stuff and there is no way it will run 13's I don't think it will run 14's! It sure will not roast the tires!


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