Engine upgrade
Thread Starter
Racer
Joined: Nov 2020
Posts: 265
Likes: 76
Engine upgrade
Hello All,
I have a 1980 Corvette with L48 that run really smooth with a new TKO600 I just put in. Only problem is no power. I got rid of cats, did dual exhaust and changed timing advance springs so not much else but some major upgrades. I figure I'm right around 200hp right now but I'd like to get to 350-400hp. Not looking to go to the track just want some power to avoid being embarrased mini vans if you know what I mean.
My two options are top end upgrade: https://www.summitracing.com/parts/sme-k-375-400 $1738 or crate engine https://www.summitracing.com/parts/mll-bp35513ctf1 $5989
I have a 1980 Corvette with L48 that run really smooth with a new TKO600 I just put in. Only problem is no power. I got rid of cats, did dual exhaust and changed timing advance springs so not much else but some major upgrades. I figure I'm right around 200hp right now but I'd like to get to 350-400hp. Not looking to go to the track just want some power to avoid being embarrased mini vans if you know what I mean.
My two options are top end upgrade: https://www.summitracing.com/parts/sme-k-375-400 $1738 or crate engine https://www.summitracing.com/parts/mll-bp35513ctf1 $5989
- Don't really want to pull engine unless I really need to. Can the CAM be changed without pulling motor?
- Anyone have experience with these top end kits. Is the 375HP listed realistic after this upgrade (I know this L48 is not made to be power demon)?
- Has anyone had issues with old L48 bumped up to this horsepower?
- If I go with top end kit should also replace stock carb with holly 650 or 750?
- I did transmission swap and have replaced heads in the past but I've never dealt with lifter lash, hydralic lifter etc. How complicated is it to swap out top end?
Last edited by joserpaq; Feb 14, 2022 at 03:56 PM.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
Thats a nice kit, no doubt.
However, a couple of things concern me.
You may run into interference issues with sparkplugs hitting the headers. In my opinion, "angled" plugs are not needed.
Next. That is quite a bit of cam duration for a low compression engine. Even with the 62cc chambers, I doubt your old 8:1 pistons will meet the need of around 10:1 CR. That cam duration usually requires some big gears out back also. Better ask Summit lots of questions.
The good side of kits is you usually get a good price for buying everything whether it fits your app or not It's kind of like ordering deluxe cheeseburger when you hate onions.... . .take it or leave it . . .
Some of us prefer to purchase parts heads, cam, Intake, independently at a higher cost, but with a specific & correct outcome instead of general "one kit fits all".
However, a couple of things concern me.
You may run into interference issues with sparkplugs hitting the headers. In my opinion, "angled" plugs are not needed.
Next. That is quite a bit of cam duration for a low compression engine. Even with the 62cc chambers, I doubt your old 8:1 pistons will meet the need of around 10:1 CR. That cam duration usually requires some big gears out back also. Better ask Summit lots of questions.
The good side of kits is you usually get a good price for buying everything whether it fits your app or not It's kind of like ordering deluxe cheeseburger when you hate onions.... . .take it or leave it . . .
Some of us prefer to purchase parts heads, cam, Intake, independently at a higher cost, but with a specific & correct outcome instead of general "one kit fits all".
Racer
Joined: May 2020
Posts: 497
Likes: 167
That intake in the summit kit won’t fit a stock Corvette hood and comes with a flat tapper cam…. Just take off the hood and pull the radiator and plenty of room to install the cam.
https://www.edelbrock.com/performer-...hevy-2089.html
This comes with the very good EPS intake (fits under the hood) and a roller cam.
https://www.edelbrock.com/performer-...hevy-2089.html
This comes with the very good EPS intake (fits under the hood) and a roller cam.
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
No way I'd buy that 350 from summit if I can get this directly from Blueprint.
https://blueprintengines.com/product...or-bp38318ctc1
https://blueprintengines.com/product...or-bp38318ctc1
Drifting
Joined: Mar 2006
Posts: 1,263
Likes: 188
From: Wabasha Mn
Hello All,
I have a 1980 Corvette with L48 that run really smooth with a new TKO600 I just put in. Only problem is no power. I got rid of cats, did dual exhaust and changed timing advance springs so not much else but some major upgrades. I figure I'm right around 200hp right now but I'd like to get to 350-400hp. Not looking to go to the track just want some power to avoid being embarrased mini vans if you know what I mean.
My two options are top end upgrade: https://www.summitracing.com/parts/sme-k-375-400 $1738 or crate engine https://www.summitracing.com/parts/mll-bp35513ctf1 $5989
I have a 1980 Corvette with L48 that run really smooth with a new TKO600 I just put in. Only problem is no power. I got rid of cats, did dual exhaust and changed timing advance springs so not much else but some major upgrades. I figure I'm right around 200hp right now but I'd like to get to 350-400hp. Not looking to go to the track just want some power to avoid being embarrased mini vans if you know what I mean.
My two options are top end upgrade: https://www.summitracing.com/parts/sme-k-375-400 $1738 or crate engine https://www.summitracing.com/parts/mll-bp35513ctf1 $5989
- Don't really want to pull engine unless I really need to. Can the CAM be changed without pulling motor?
- Anyone have experience with these top end kits. Is the 375HP listed realistic after this upgrade (I know this L48 is not made to be power demon)?
- Has anyone had issues with old L48 bumped up to this horsepower?
- If I go with top end kit should also replace stock carb with holly 650 or 750?
- I did transmission swap and have replaced heads in the past but I've never dealt with lifter lash, hydralic lifter etc. How complicated is it to swap out top end?
Le Mans Master
Joined: Apr 2011
Posts: 6,284
Likes: 1,170
From: Hermosa
If you go the top end kit route, the current pistons are not ideal for power. I tried to go down this road myself. Ended up rebuilding the bottom end and top end.https://www.corvetteforum.com/forums...er-size-2.html
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Pro
Joined: Jun 2021
Posts: 505
Likes: 230
Dump the L48, get a 383 crate with a roller cam around 230 duration, .550 lift, 10:1 compression, aluminum heads, hypertonic or forged pistons. You will end up there anyway after spending money on a top end kit that will be disappointing with that lower end.
Thread Starter
Racer
Joined: Nov 2020
Posts: 265
Likes: 76
I really appreciate input. I guess I'll have to save some $$ to get something like this.
https://blueprintengines.com/product...-drop-in-ready
https://blueprintengines.com/product...-drop-in-ready
Drifting
Joined: Dec 2020
Posts: 1,586
Likes: 956
From: Central Florida
2024 Corvette of the Year Winner - Modified
2023 C3 of the Year Winner - Modified
2021 C3 of the Year Finalist - Modified
I have an l48 with some top end upgrades. It can handle it. Check out skip white performance for crates. If you want to stay small block consider a 434 from them. Some hate on their products but I’ve dealt with them as many others here have and I can say they do a good job. Good prices but they buy their parts in bulk.
Instructor
Joined: Nov 2011
Posts: 195
Likes: 147
It's not so much the pistons, as the heads are killing you. Stock heads will pour at near 76CC! I did an '80 for a customer and used GMPP fast burn (small chamber heads) on a stock bottom end. I used a hydraulic roller retro-fit, and the GMPP intake for a ZZ4. With the cam pulled forward a couple of degrees, it made just over 360. Final compression with an .027 gasket came in at 9.6:1. Holley 650 (vacuum secondary, electric choke) The car was fun to drive, but when the rear gears went to 3.73, it was a blast. Total timing was at 36 on the dyno and I used 93 octane.
Brandon Unklesbay
All-In Performance, LLC
Brandon Unklesbay
All-In Performance, LLC
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,034
Likes: 9,156
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
how much horsepowerr is that aluminum rear end going to handle?
Thread Starter
Racer
Joined: Nov 2020
Posts: 265
Likes: 76
It's not so much the pistons, as the heads are killing you. Stock heads will pour at near 76CC! I did an '80 for a customer and used GMPP fast burn (small chamber heads) on a stock bottom end. I used a hydraulic roller retro-fit, and the GMPP intake for a ZZ4. With the cam pulled forward a couple of degrees, it made just over 360. Final compression with an .027 gasket came in at 9.6:1. Holley 650 (vacuum secondary, electric choke) The car was fun to drive, but when the rear gears went to 3.73, it was a blast. Total timing was at 36 on the dyno and I used 93 octane.
Brandon Unklesbay
All-In Performance, LLC
Brandon Unklesbay
All-In Performance, LLC
Thread Starter
Racer
Joined: Nov 2020
Posts: 265
Likes: 76
Instructor
Joined: Nov 2011
Posts: 195
Likes: 147
I'm in Ohio. Part availability sucks currently, so you might want to procure all of your parts before you down the car with spring around the corner. A good head with a smaller chamber (64-ish) and a smaller runner (180-ish) will serve you well. You really won't need the hydraulic roller, but it does help. It doesn't need to be the ZZ4 head/intake combo. They worked well for years ago though with a proper spec'd cam.