Chevy LS engine with carb. drag race potential question.

[Dragsinger]

For those of you with LS engine experience. Using the example of a 4.00" bore x 3.75 stroke, iron block, well done cathedral port heads, cast intake, methanol carb, dome piston providing at least 12:1 compression, enough cam for 7400 - 7500 shift point.

Given the above guideline, what is the power per cubic inch potential?

I know from experience a first gen small block can make around 1.65 - 1.7 with off the shelf parts and well-done heads. Is the LS in about that same range? Do some of you with LS experience see any advantage with the LS design over the first gen design with such specifications?

[Walter R. Malik]

For those of you with LS engine experience. Using the example of a 4.00" bore x 3.75 stroke, iron block, well done cathedral port heads, cast intake, methanol carb, dome piston providing at least 12:1 compression, enough cam for 7400 - 7500 shift point.

Given the above guideline, what is the power per cubic inch potential?

I know from experience a first gen small block can make around 1.65 - 1.7 with off the shelf parts and well-done heads. Is the LS in about that same range? Do some of you with LS experience see any advantage with the LS design over the first gen design with such specifications?

With well done Cathedral port heads you should certainly be able to match that ... L92/LS3 heads should better it, easily.

[Dave B]

I take it you are talking like a 23 head with those low hp per inch listings?
The ls has some decent port area and ssr height over some conv 23 heads. Valve angle is better in ls. Imo if perimeters of valve size stay same. Let's say 2.125 in both conv 23 and ls 15 deg. We used to make 750 hp with 23 rolled over brodix 10 ri heads back in the 90s. I did 2.100 valve ls casting and we made 805 hp. Very similar cam profiles. It is less work to do ls platform because of area in port etc. Imo the valve angle and ssr in ls helps the wet flow/ burn pattern characteristics also. If I had the choice of 23 afr 245 head or factory ls casting ,I would take the 15 deg valve advantage. Jmo. Now you take a current 15- 16 wedge head and you should make 800 hp with them also now days.
Sprint 15 deg #12 brodix castings would easily do 340 cfm. We used to make 840 hp, injected 410 inch, alky sprint engs in 93. These are just baseline examples. The sprint eng I gave example of had 2 pts more comp also.

[Walter R. Malik]

I take it you are talking like a 23 head with those low hp per inch listings?
The ls has some decent port area and ssr height over some conv 23 heads. Valve angle is better in ls. Imo if perimeters of valve size stay same. Let's say 2.125 in both conv 23 and ls 15 deg. We used to make 750 hp with 23 rolled over brodix 10 ri heads back in the 90s. I did 2.100 valve ls casting and we made 805 hp. Very similar cam profiles. It is less work to do ls platform because of area in port etc. Imo the valve angle and ssr in ls helps the wet flow/ burn pattern characteristics also. If I had the choice of 23 afr 245 head or factory ls casting ,I would take the 15 deg valve advantage. Jmo. Now you take a current 15- 16 wedge head and you should make 800 hp with them also now days.
Sprint 15 deg #12 brodix castings would easily do 340 cfm. We used to make 840 hp, injected 410 inch, alky sprint engs in 93. These are just baseline examples. The sprint eng I gave example of had 2 pts more comp also.

I am talking comparing a small block Chevrolet with comparable O.E.M. production heads to an LS with Cathedral port heads.

NOT apples to grapefruits.

[Dave B]

Walter
I should of quoted who I was talking too. It had nothing to do with you at all.
Drag singer was talking 1.6 hp per inch. That seems like 23 territory. That is who I was addressing. I have made 800 plus hp with cathedral port heads . But they were not anything like factory crap when I was done with them. So Walter that is now comparing your apple to a much better grapefruit.lol