L98 build up
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 1,179
Likes: 5
From: Lake Orion Michigan
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?
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?
Team Owner
Joined: Sep 2001
Posts: 62,142
Likes: 1,729
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
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
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
Corvette Enthusiast
Joined: Oct 2007
Posts: 6,794
Likes: 2,706
From: So. Cal.
2025 C7 of the Year Finalist- Unmodified
2024 C7 of the Year Finalist - Unmodified
2023 C7 of the Year Finalist - Unmodified
mods
I'll take the LT4. How much does all these mods cost? 
Advanced
Joined: Mar 2006
Posts: 99
Likes: 0
From: Mesa AZ
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!
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 1,179
Likes: 5
From: Lake Orion Michigan
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Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
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
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
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 1,179
Likes: 5
From: Lake Orion Michigan
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
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
We will be at Norwalk today and Saturday for the ADRL Pro mod outlaw race.
Le Mans Master
Joined: May 2007
Posts: 8,448
Likes: 27
From: Valparaiso
What did you feel ?
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
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.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
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?
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?
Burning Brakes
Joined: Feb 2008
Posts: 988
Likes: 7
From: Sarasota Fl
Pro
Joined: Jan 2008
Posts: 584
Likes: 1
From: Near Lockport NY Black 1986 Coupe
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?
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?
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 1,179
Likes: 5
From: Lake Orion Michigan
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
Burning Brakes
Joined: Apr 2005
Posts: 1,110
Likes: 0
From: JUPITER FLORIDA
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.
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.
Pro
Joined: Jun 2001
Posts: 520
Likes: 6
From: Elverson PA
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.
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; Aug 22, 2008 at 05:05 PM.
Thread Starter
Burning Brakes
Joined: Apr 2008
Posts: 1,179
Likes: 5
From: Lake Orion Michigan
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.
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.
