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

Building a sub-5s 0-60 L98

 
Old 04-04-2019, 02:37 AM
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obijohnkenobe
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Default Building a sub-5s 0-60 L98

Hello everyone. I've been doing a LOT of reading and researching in an effort to find out what it would take to make a '91 C4 competitive with a base C6 or C7... and that seems to be 450 hp or thereabouts. I'd be starting with a L98, and thinking I'd need to rebuild it into a 383 stroker, get the factory heads ported, get a mild but decent cam and 1.6" rockers, and throw on a FIRST TPI manifold and headers along with a good exhaust, e.g., Corsa. With the factory D44 rear end and 6-speed, am I in the ball park? I figure this would be about a $5K build give or take... is that right? I want something that looks very much like stock upon first glance under the hood, but that runs like stink. Could I get by with the factory TPI but with large tube ASM runners, perhaps the Edelbrock manifold, have the plenum ported and the runners and baseplate extrude-honed? Comments?

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Old 04-04-2019, 08:11 AM
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Budget a little low unless you have access to a machine shop and ability to do most or all of the work. Getting there by going carb and a little luck searching used racing part sites. A 3.73 -4.33 gear will be helpful. You should be able to meet your goals. Tuning factory efi canbe time consuming and expensive. Stand alone efi can eat up half your budget. Nitrous Oxide another option.
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Old 04-04-2019, 08:13 AM
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You could probably get low 5s on the stock unit... but if you are trying to increase the usuable power band then it really shouldn't matter all to much going to something like the first... you'll get a mild boost up top compared to stock. The important thing is making sure to match all the parts. If you do a 383 use decent heads... the factory ported may get you there but you can do much better just bolting on imo and then you don't have to worry about having all the extra work done. Work the exhaust some use a mild cam in the 220s duration. It will be very drivable and pull well. Having the extra torque down low will make you launch better as well... so long as you can put the power down that is. You're on the right track.
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Old 04-04-2019, 08:37 AM
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383, Mini Ram, AFR Heads, Bigger Injectors, 220/220-ish cam, larger fuel pump, larger injectors, headers, high flow cats, 3.73 gear. Still may not get there, but this should be in the 400-450hp.

You are asking to near double your output, it won't be easy.

Just to get it to perform like an LT1 will require Head work, injectors, and a manifold change... getting into C7 territory...You would probably be money ahead to start with a C5 unless you are tied to the C4 or TPI for another reason. Remember, the TPI was designed to make a lot of torque and feel strong in normal driving conditions. It is not a high RPM/High HP system. The FAST system flows well but still will not outperform a short runner intake above 4500RPMS.
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Old 04-04-2019, 08:59 AM
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My 88 will run with my 2019, traction becomes a problem with the torque I make. You will need pretty good tires, but new cars are more efficient at putting engine power to the ground. Top end, the 2019 will pull away, and will always feel more stable. Gun my 88 and she might go sideways.

398 Superram, AFR 195 heads, Crane Gold 1.6RR, Crower cam, TPiS headers, true dual exhaust. I have between 10-12K in the engine alone. Traction will be just as much a problem with the FIRST if you choose that intake, and I don't think the FIRST will have any success after 60mph.
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Old 04-04-2019, 09:15 AM
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Originally Posted by obijohnkenobe View Post
Hello everyone. I've been doing a LOT of reading and researching in an effort to find out what it would take to make a '91 C4 competitive with a base C6 or C7... and that seems to be 450 hp or thereabouts. I'd be starting with a L98, and thinking I'd need to rebuild it into a 383 stroker, get the factory heads ported, get a mild but decent cam and 1.6" rockers, and throw on a FIRST TPI manifold and headers along with a good exhaust, e.g., Corsa. With the factory D44 rear end and 6-speed, am I in the ball park? I figure this would be about a $5K build give or take... is that right? I want something that looks very much like stock upon first glance under the hood, but that runs like stink. Could I get by with the factory TPI but with large tube ASM runners, perhaps the Edelbrock manifold, have the plenum ported and the runners and baseplate extrude-honed? Comments?
I think it can be done for around the dollars you mention, if you are handy and do the work yourself. machine shop work is not that expensive, buy reasonable parts but don't go crazy and assemble the engine yourself.

-355 or 383 will work
-Cast crank since you are not reving it to the moon with a First or TPI intake, assume a 6000 RPM or earlier shift
-Stock rods will be fine
-Forged pistons would be nice in the 10.25 to 10.5 CR range. Hypers would be OK but forged would be my choice.
-Assembly the engine yourself
-Add long tube headers
-Stock heads ported (maybe but if you have to pay someone it may be better to buy some aftermarket heads like trick flow or others that are similar) $1000 for heads goes a long way these days, that would probably be the porting cost
-Hyd roller cam like the ZZ9 or Hot cam, or work with someone to come up with a newer custom grind that has faster ramps for better power but still designed for good TPI performance
-30 lb injectors and a tune
-First would probably be the cheapest with the best power potential, a TPI with aftermarket base and runners may cost more then the first and have less potential. (look for used could be your best bet) I assume you wnat the TPI look so I have ruled out the Superram or Mini ram
-1.5 or 1.6 rockers are fine, if you spec the cam correctly either rocker can be used. (In other words target the lift you want and get a cam to do that with 1.5 rockers) If you need more lift from an off the shelf grind then use 1.6 rockers

One more comment, if your stock engine is good use it! The 350 willl get your goals with heads, cam, intake, headers and tune. (Saves money)

This combination should be around 350 to 400 HP (maybe more) and it will run hard.

I had a 355 with a Large tube TPI combination and it ran hard, 300 HP to the tires, around 360 HP at the crank and the car ran high to mid 12's at 108 MPH in the 1/4. Not 450 HP but ET wise was close to the new cars.

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Old 04-04-2019, 09:50 AM
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LS swap that ****! Why spend $5k + in hopes of running with a stock C6 or stock C7? Especially when most c4s are only worth about that to begin with?
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Old 04-04-2019, 09:55 AM
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Originally Posted by obijohnkenobe View Post
Hello everyone. I've been doing a LOT of reading and researching in an effort to find out what it would take to make a '91 C4 competitive with a base C6 or C7
a stock 91 6 speed coupe generally runs 0-60 in the mid-high 5 second range if you compare apples to apples stock LS3 C6 manual and C7 LT1 manual coupes are hitting low 4ís high 3ís figure abut TWO full seconds against a Z51 Manual Stingray in the 1/4 youíre talking about a car that traps around 100 with a car that can trap close to 120 SURPISING a poorly driven one at the stoplight with some 3.73ís, drag radials and FULL bolt ons can be done but hitting 120 in the 1/4 isnít going to happen with a streetable LONG RUNNERED N/A TPI

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Old 04-04-2019, 10:11 AM
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Originally Posted by vader86 View Post
My 88 will run with my 2019, traction becomes a problem with the torque I make. You will need pretty good tires, but new cars are more efficient at putting engine power to the ground. Top end, the 2019 will pull away, and will always feel more stable. Gun my 88 and she might go sideways.

398 Superram, AFR 195 heads, Crane Gold 1.6RR, Crower cam, TPiS headers, true dual exhaust. I have between 10-12K in the engine alone. Traction will be just as much a problem with the FIRST if you choose that intake, and I don't think the FIRST will have any success after 60mph.
People confuse efficiency of putting down power with technology... it isn't more efficient, the computer just reduces power enough so it doesn't break them lose. Big difference. It may have marginally better rear geometry but it isn't better at putting the power down. I've tried it without it... it isn't any better but the wider meats help a little. That's the big difference I've seen.
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Old 04-04-2019, 10:27 AM
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I often wonder with the original post how many of these people actually follow through ??
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Old 04-04-2019, 11:40 AM
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Originally Posted by Y-bodluvr View Post
a stock 91 6 speed coupe generally runs 0-60 in the mid-high 5 second range if you compare apples to apples stock LS3 C6 manual and C7 LT1 manual coupes are hitting low 4’s high 3’s figure abut TWO full seconds against a Z51 Manual Stingray in the 1/4 you’re talking about a car that traps around 100 with a car that can trap close to 120 SURPISING a poorly driven one at the stoplight with some 3.73’s, drag radials and FULL bolt ons can be done but hitting 120 in the 1/4 isn’t going to happen with a streetable LONG RUNNERED N/A TPI
People worry about trap speed too much. It is irrelevant, a drag race is about time, not speed. Reaction time and ET. Ever seen a top fuel dragster blow its tires off mid track and shut down? ET around 6 seconds and a trap of 150mph? Still got there in 6 seconds.

You can surprise a lot of people with more power using a well tuned chassis that gets the first 60' and 100' down well.

Another Example... Tesla P100D Model S versus a Hellcat. In the 1/4 mile the torque and traction trumps the Hellcat's power. The extra horsepower in the Heelcat shows in trap speed... but the Tesla gets there first. Many TPI builds have got into the 11s using long(ish) runners.

A very wise old drag racer once told me you build a car from the back to the front, because all the power in the world means nothing if you can't put it to the pavement.

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Old 04-04-2019, 11:43 AM
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Originally Posted by slow_zo6 View Post
LS swap that ****! Why spend $5k + in hopes of running with a stock C6 or stock C7? Especially when most c4s are only worth about that to begin with?
Because by the time you have a functional LS in there, you are way past $5k. Especially if you want all your dash functions working.

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Old 04-04-2019, 02:03 PM
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Originally Posted by KyleF View Post
Because by the time you have a functional LS in there, you are way past $5k. Especially if you want all your dash functions working.
it can be done much cheaper. Def not worth it spending $5k on some archaic set up in my opinion at least.

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Old 04-04-2019, 02:16 PM
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Originally Posted by KyleF View Post
People worry about trap speed too much. It is irrelevant, a drag race is about time, not speed. Reaction time and ET. Ever seen a top fuel dragster blow its tires off mid track and shut down? ET around 6 seconds and a trap of 150mph? Still got there in 6 seconds.

You can surprise a lot of people with more power using a well tuned chassis that gets the first 60' and 100' down well.

. Many TPI builds have got into the 11s using long(ish) runners.
This is true and basically what I said YES an L98 Long runnered 383 can match the new cars 0-60 especially in an automatic with stall/gears/ slicks etc it WONT match trap speed though
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Old 04-04-2019, 02:22 PM
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Originally Posted by slow_zo6 View Post
it can be done much cheaper. Def not worth it spending $5k on some archaic set up in my opinion at least.
You are not getting a 450hp LS in there maintaining all vehicle functionality for $5k. I have looked into it as an option and as with most swaps, it is a lot more involved than most give it credit for. I will say there are advantages to go LS, but there are some hurdles. If you are referring to getting a junk yard LS1/LS2... that's a roll of the dice too. However, if you see above I mentioned just starting with a C5 for this reason. I still believe you would be money ahead if you want to do an LS by selling the C4, buying a C5 and start from there.
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Old 04-04-2019, 02:55 PM
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Originally Posted by obijohnkenobe View Post
what it would take to make a '91 C4 competitive with a base C6 or C7... and that seems to be 450 hp or thereabouts.
Back in 2001 I ran a [email protected] in a 1990 L98 GTA I had car had everything done SLP package+ 2800 torque converter+ drag radials but stock heads&cam probably didnít put out much over 300hp used to take down LS cars all the time on the street 0-60 was probably in the mid 4 second range
Even though there was no C6 yet Im sure it would have given an LS2 2.73 geared automatic convertible FITS

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Old 04-05-2019, 08:09 AM
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Originally Posted by KyleF View Post
You are not getting a 450hp LS in there maintaining all vehicle functionality for $5k. I have looked into it as an option and as with most swaps, it is a lot more involved than most give it credit for. I will say there are advantages to go LS, but there are some hurdles. If you are referring to getting a junk yard LS1/LS2... that's a roll of the dice too. However, if you see above I mentioned just starting with a C5 for this reason. I still believe you would be money ahead if you want to do an LS by selling the C4, buying a C5 and start from there.


I agree

FWIW I have a 462rwhp running through a 3000 stall converter, and minus headers (already had) tune and injectors, I have about $5,000. in it. RKLESSDRIVER built it for me. With careful pricing it can be done. For that money I have a 4 bolt splayed block, forged rotating assy, AFR heads, Mike Jones Cam, etc. On the first day to the track, it ran an 11.19 at 124.6 mph with a soft 1.60 60ft.
Your not going to get that out of a $5,000.00 LS conversion unless you add Nitrous, or a blower. I may be wrong, and if I am, show it too me.


But, to the OP if 0 to 60 is your only concern, put a low gear in the rear and a good set of drag radials..... That may be all you need to get a 5 sec. 0 to 60
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Old 04-05-2019, 10:24 AM
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Originally Posted by 93 ragtop View Post

I agree

FWIW I have a 462rwhp running through a 3000 stall converter, and minus headers (already had) tune and injectors, I have about $5,000. in it. RKLESSDRIVER built it for me. With careful pricing it can be done. For that money I have a 4 bolt splayed block, forged rotating assy, AFR heads, Mike Jones Cam, etc. On the first day to the track, it ran an 11.19 at 124.6 mph with a soft 1.60 60ft.
Your not going to get that out of a $5,000.00 LS conversion unless you add Nitrous, or a blower. I may be wrong, and if I am, show it too me.


But, to the OP if 0 to 60 is your only concern, put a low gear in the rear and a good set of drag radials..... That may be all you need to get a 5 sec. 0 to 60
$3k of LS engine can get you near that power level. It is just whether or not you can get it in the car for the other $2k.

I bought my '84 with the swap already done for $8500. It isn't 462rwhp but it does make 420rwhp with a mild 220/224 .575/.575 cam. That car also came with C5 brake swap, 17" replica C6 Z06 wheels, D44 swap and TKO 600 conversion.
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Old 04-05-2019, 11:30 AM
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Originally Posted by Krusty84 View Post
$3k of LS engine can get you near that power level. It is just whether or not you can get it in the car for the other $2k.

I bought my '84 with the swap already done for $8500. It isn't 462rwhp but it does make 420rwhp with a mild 220/224 .575/.575 cam. That car also came with C5 brake swap, 17" replica C6 Z06 wheels, D44 swap and TKO 600 conversion.
Leave it alone man. If someone wants to spend thousands on a gen I sbc build hoping to make 400hp thatís their god given right.
Just be sure to use a 3/4 cam and have the cragars to match. 👌
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Old 04-05-2019, 12:06 PM
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Funny thing is these days the c5-7 guys are all using "stage xx" cams, goofy names etc. History repeats itself
LS1 isnt impressive by any means unles someone has really put some work into it. by the time they put say an AFR head, cam, headers tune etc they are going to spend a TON. So the Gen 1 needs a little more cam timing to get there not a big deal. I like the idea of a world block that takes an LS head, add distributor and it bolts in. Kind of an SB2 type engine on the cheap
If anyone remembers mseven he had a big ci SB2.2 with a hyd roller st driven motor that made well over 730chp, not hard to drive at all. Getting off track again..
Lots of LS swaps but one done right isnt cheap.

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