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86 C4 4speed trying to make it a 9sec without swap any suggestions?

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86 C4 4speed trying to make it a 9sec without swap any suggestions?

 
Old 05-06-2019, 06:31 AM
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The Dice Club
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Default 86 C4 4speed trying to make it a 9sec without swap any suggestions?

Hi my name is Joe Dice. I'm new to forums and herd it was a great place to get help with Corvette builds. As the title states I do have a 86 C4 with a 4 speed with overdrive. Has the L98 in it and I want to make it a 9 sec car if possible without swapping. If I have to swap it will only be for the Ls but trying to keep it as original as possible. Any suggestions or comments would be highly appreciated.
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Old 05-06-2019, 07:31 AM
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You'll need a minimum $15,000 budget to do it on the original L98, and that's if you do all of your own labor.

By the way, most newbies think they are going to run 9's on their manual transmission. About .001% can actually do it.
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Old 05-06-2019, 07:43 AM
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….. It should already be capable of running 9's … 1/8th mile …..
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Old 05-06-2019, 07:47 AM
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Originally Posted by JoeNova View Post
You'll need a minimum $15,000 budget to do it on the original L98, and that's if you do all of your own labor.

By the way, most newbies think they are going to run 9's on their manual transmission. About .001% can actually do it.
I mean I know my 4 speed is going to have to get swapped because the overdrive is a pain. I'm new to the forums not the drag. I go to the YouTube callouts and English town and maple grove. This is just the first time heavily modding a Vett and don't want to do it wrong. I know I'm bound to make mistakes, but thought this would be a good place to start so I make less of them. I know it will be a while before I hit 9xs I just want a point in the right direction.

Last edited by The Dice Club; 05-06-2019 at 07:48 AM. Reason: Wanted to add more
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Old 05-06-2019, 08:17 AM
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Like I said, $15k minimum is a start. I've built entire cars to run 9's for less than it would take a manual C4 to run it.
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Old 05-06-2019, 08:39 AM
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9 sec car? At least 500RWHP I would think. You could try a 200shot and hope it lasts more than 1 pass. That's probably all the rear would be able to take with sticky tires anyway.

Last edited by pacoW; 05-06-2019 at 08:39 AM.
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Old 05-06-2019, 08:42 AM
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You want to run 9's with an L98 C4 and you want to keep it an L98 with a stick? Well, first you'll need to swap the trans for a ZF six speed, then you'll need to convert the rear end to a solid axle 9 inch or 12 bolt, and to make the L98 do it you'll need a blower and a 500 horsepower nitrous shot...

Last edited by TheGreek!; 05-06-2019 at 08:43 AM.
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Old 05-06-2019, 08:49 AM
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500whp won't do it with a manual trans at that weight. 600whp @ 3400 lbs with a 6 speed netted us a best of 10.69 @ 129.
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Old 05-06-2019, 08:56 AM
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Originally Posted by TheGreek! View Post
You want to run 9's with an L98 C4 and you want to keep it an L98 with a stick? Well, first you'll need to swap the trans for a ZF six speed, then you'll need to convert the rear end to a solid axle 9 inch or 12 bolt, and to make the L98 do it you'll need a blower and a 500 horsepower nitrous shot...
The Dana 44 can do it. But the cost of making it handle that power may be close to the price of swapping in a budget solid axle. At that point you'll need to weigh your options.

Massive weight reduction is your biggest friend. But if you want to keep it as original as possible, there's only so much you can do.
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Old 05-06-2019, 09:36 AM
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Original what?
Youll need a different motor trans and rear....probably 20k (minimum)+ to dump into it
Couple guys here running 9s they will pipe in

500rahp wont come close to 9s

Last edited by cuisinartvette; 05-06-2019 at 09:37 AM.
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Old 05-06-2019, 09:53 AM
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Engine - Forged bottom end, decent set of heads, intake manifold, boost (pick your flavor. If you can weld, turbos are BY FAR the cheapest). MS3x or Holley EFI.
Transmission - ZF 6-Speed is about the only way to go to keep a manual in a C4. You can swap to T56 with some work (again, if you can weld).
Rear diff - Solid or good poly bushings where it mounts to the frame, full axle upgrade. Late-C6/C7 hubs, outer stubs, axle shafts, inner stubs. I'm not sure on the carrier itself for strength.

Last edited by JoeNova; 05-06-2019 at 09:54 AM.
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Old 05-06-2019, 01:05 PM
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Why do so many people show up here and want to make 500 hp out of a 245 hp engine? I love the body and engine compartment but trying to squeeze that much hp out of the anemic L98 seems like it would be difficult and very, very expensive.

My other Corvette has a 427 and makes way too much hp for just driving around casually. Everywhere you go people are going to know you have power, not much of a "sleeper". The worst part is the police that think you are an idiot and follow you around waiting for you to do anything illegal so they can write you up. Every time I take my 500+ hp C3 Corvette out I have tons of idiots that want to race me in their Civic. The funniest part is they actually think a (Mostly stock) Civic can run with my C3, I just laugh and drive off at my own pace. Not all C3's came with a 1977 engine between the frame rails. I like the fact that I can put a nice small block in it or the biggest baddest big block and they both fit easily.

If you want a Corvette that can go fast easily or at least more easily, buy a newer C6 or C7 or go back and get a early C3. The early C3's are fun cars and they can be made fast using the old methods. I love the wind in my hair, the sound of my 427 and the experience of driving a car built in 1968 with all the technology they could squeeze in. My C3 is my speed toy, the C4 was purchased as my wife was feeling left out. I have enjoyed the Corvette experience for close to 28 years now and know that I have been one of the lucky ones to have a Corvette in the first place. I have never owned a car as long as I have had my 1968 C3. I have great memories of driving around with my son in his Car Seat facing the rear while driving the convertible with his baseball hat and sunglasses on. Funny thing that both of my kids want to own their own Corvettes.

I hope you find a way to make enough power that you are happy with your Corvette! My C4 coupe is a great cruising car and I even broke 30 m.p.g. on I-95 between Washington and Baltimore, Maryland. Corvettes are a well designed product and I like them all.

Best Regards,
Chris
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Old 05-06-2019, 08:37 PM
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Here is what runs mid 9s.
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Old 05-06-2019, 09:20 PM
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Yep, agree. Buy a new ZR1
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Old 05-07-2019, 08:29 AM
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Originally Posted by ctmccloskey View Post
Why do so many people show up here and want to make 500 hp out of a 245 hp engine? I love the body and engine compartment but trying to squeeze that much hp out of the anemic L98 seems like it would be difficult and very, very expensive.

My other Corvette has a 427 and makes way too much hp for just driving around casually. Everywhere you go people are going to know you have power, not much of a "sleeper".
My 4.8 started life with like 255 HP and I added 600 to that with nothing but a cam and boost.

Boost solves the sleeper issue too. Sure, when you have a 500+ horsepower 427, its going to be loud. Its going to be cammed. Its going to sound fast.
With boost, 500 horsepower comes and goes by accident, and the engine can be every bit as quiet as stock, because you can even run the stock cam with stock displacement.
Its absolutely plausible. Doing it N/A with the L98 isn't going to be easy, and it will be much more expensive than boost.
A pair of $99/each ebay turbos would make enough power to get a C4 into the 9s, but there is going to be much more to the equation than just those.

Originally Posted by Capt Mike View Post
Yep, agree. Buy a new ZR1
15k into your C4 is a LOT cheaper than 120k for a ZR1.
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Old 05-07-2019, 02:09 PM
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I hate to beat the Cleetus drum, but if you dont know who he is, look up Cleetus McFarland on YouTube and watch the c6 videos. From what I remember, he ended up with a boosted water intercooler 5.3, built power glide, and a host of other goodies to that made 900 some hp and a 9 (or was it 8?) second quarter.
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Old 05-07-2019, 09:26 PM
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No offense, throw all the boost you can to a stock 2 bolt main Tpi tork monster the only thing going 9s are the rods running away from the pan! lol

It takes a LOT guys, more than a motor or power #. Everything from bumper to bumper is going to need touching on, suspension work and much more. Takes lots of time/money its endless.
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Old 05-07-2019, 11:17 PM
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Originally Posted by The Dice Club View Post
I do have a 86 C4 with a 4 speed with overdrive. Has the L98 in it and I want to make it a 9 sec car.
9ís with a TPI manual?

Last edited by Y-bodluvr; 05-07-2019 at 11:20 PM.
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Old 05-07-2019, 11:37 PM
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Lots and lots of spray and pray it makes it to the stripe.
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Old 05-08-2019, 08:52 AM
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Original as possible 9 second c4 ?

God I love this forum!

-- Joe
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