L92 600 Crank HP

[MD383]

Hello, I have a L92 that will be a N/A street/strip build in a 67 Chevy II. I was looking at comp cam. https://www.summitracing.com/parts/cca- ... /chevrolet What’s needed to get 600hp at the crank? Will this parts combination get me over the HP goal? The engine is apart so I can make changes to get to there. I’m used to some surging down low with a large cam and a manual transmission. I’m not driving around parking lots at 5mph.

Dome -2cc pistons I’ll keep the quench tight and aim for around 11.2-11.5 compression to stay on pump gas
Stock bottom end
823 heads not milled 70cc chambers but can mill them if need be
1.8 full roller rockers
850 holley double pumper?
Edelbrock 71197 dual plane manifold
2” headers
3.73 rear gear
Manual transmission
Car will be almost 3,000 pounds without me in it

[Walter R. Malik]

To get that kind of power you will probably need to get up-to or over 7,000 RPM ... for that engine size the headers are probably to big.

Hope you can get there...

[mag2555]

Those heads are said to have a peak intake flow of 315 to 317, and your cam will need to have enough lift to get you 290 cfm of 317.

With the intake flow numbers you need I don’t think a duel plane is the way to go for a manifold, and 2” tubes will reduce too much average torque if you going to run the car in the 1/4 mile.

[sbcthor]

Dont use those carb manifolds those things are garbage on a LS.
Unless its like a dominator/4500, an stock LS3 manifold would be better

[MD383]

To get that kind of power you will probably need to get up-to or over 7,000 RPM ... for that engine size the headers are probably to big.

Hope you can get there...

Ok maybe 1 7/8” headers?

[MD383]

Dont use those carb manifolds those things are garbage on a LS.
Unless its like a dominator/4500, an stock LS3 manifold would be better

Definitely going carbureted.

[MD383]

Those heads are said to have a peak intake flow of 315 to 317, and your cam will need to have enough lift to get you 290 cfm of 317.

With the intake flow numbers you need I don’t think a duel plane is the way to go for a manifold, and 2” tubes will reduce too much average torque if you going to run the car in the 1/4 mile.

Ok, how about 1 7/8” headers? I wanted to use the dual plane because I’ll be on the street mostly and after doing some research the dual plane seemed to suit my needs better. https://www.onallcylinders.com/2020/09/ ... d-4-8l-ls/

[Dave B]

Those intakes have horrible distribution and runner sizing and taper. You will need someone that really understands intake manifold porting if you want to get it straightened out. Your 4 corner runners will look waaaayyyyy different than 4 center. If you don't get after your setup I'm going to say 540 - 555 hp will be allot more of a reasonable expectation.

[MD383]

Those intakes have horrible distribution and runner sizing and taper. You will need someone that really understands intake manifold porting if you want to get it straightened out. Your 4 corner runners will look waaaayyyyy different than 4 center. If you don't get after your setup I'm going to say 540 - 555 hp will be allot more of a reasonable expectation.

I wasn’t aware of the bad rep the dual planes had. I’ve been running them on all my street SBC/BBC setups for years. I always chose to give up top end hp for more tq and hp earlier down low where a street car lives most of its life.

[Dave B]

I was looking at pick of intake you posted on that's on dyno. I guess I misread what you were asking ?

[Dave B]

Those intakes have horrible distribution and runner sizing and taper. You will need someone that really understands intake manifold porting if you want to get it straightened out. Your 4 corner runners will look waaaayyyyy different than 4 center. If you don't get after your setup I'm going to say 540 - 555 hp will be allot more of a reasonable expectation.

I wasn’t aware of the bad rep the dual planes had. I’ve been running them on all my street SBC/BBC setups for years. I always chose to give up top end hp for more tq and hp earlier down low where a street car lives most of its life.

Well if you want 600 real world hp you better concentrate on what happens from 6500 rpm and up. When my daughter was 18 we had her racing in a class that couldn't port intakes or heads. I let her do what she wanted on engine. Her first attempt made 540 hp on dyno at 4.070 bore and 3.625 stroke. 11 .65 to 1 on pump gas .It had almost identical cam you stated in numbers. She ran 7.18 best at 3380. It had dual plane on dyno and made 522 hp. We put single plane like in that picture you post and made 537 hp. She had 1-7]8 headers. 850 carb.

[MD383]

I was looking at pick of intake you posted on that's on dyno. I guess I misread what you were asking ?

The picture is for a link for a dyno comparison between single vs dual plane. I believe victor jr vs edelbrock rpm.

[MD383]

Those intakes have horrible distribution and runner sizing and taper. You will need someone that really understands intake manifold porting if you want to get it straightened out. Your 4 corner runners will look waaaayyyyy different than 4 center. If you don't get after your setup I'm going to say 540 - 555 hp will be allot more of a reasonable expectation.

I wasn’t aware of the bad rep the dual planes had. I’ve been running them on all my street SBC/BBC setups for years. I always chose to give up top end hp for more tq and hp earlier down low where a street car lives most of its life.

Well if you want 600 real world hp you better concentrate on what happens from 6500 rpm and up. When my daughter was 18 we had her racing in a class that couldn't port intakes or heads. I let her do what she wanted on engine. Her first attempt made 540 hp on dyno at 4.070 bore and 3.625 stroke. 11 .65 to 1 on pump gas .It had almost identical cam you stated in numbers. She ran 7.18 best at 3380. It had dual plane on dyno and made 522 hp. We put single plane like in that picture you post and made 537 hp. She had 1-7]8 headers. 850 carb.

Interesting, what intake made the 540?

[Dave B]

Holley 300-291 is single plane she has in that class

[MD383]

Holley -321 is single plane she has in that class

You mean 300-131?