L5 or L6 Difference between them

[nsarvis]

Hi all, I'm trying to find the difference between the L5 454 and the L6 454 produced by GM. I have a 454 in my Vert but I don't know if it is a L5 or a L6, I have done some research and it appears that the Case is the same but the HP is completely different. The L6 has an aluminum intake and four barrel Carb increasing the HP I guess ??? any help here would be great, mine does have an aluminum intake and the four barrel carb, Thanks again, Noah

 

[Peer81]

Hello Nsarvis

I see you have a 81 vette but they never came with a 454, maybe you want to contact a moderator to move this topic to the general section of the c3 technical area. Good luck!

Groeten Peter.

 

[Tom Bryant]

The LS5 was basically a 427/390 with more cubes. It ran a low rise oval port intake and had oval port standard performance heads and a passenger car smooth hydraulic cam. It was the same thing you got in an Impala if you ordered a 454. It was rated at 390 hp in1970 but this number fell until it died in 1975.

The LS6 in 1970 was not available in Corvettes, Chevelles only. It had higher compression, a solid lifter cam. open chamber big valve and rectangular port heads, a high performance aluminum intake and a big Holley carb. It was rated at 450 hp. In 1971 when the LS6 was available in Corvettes it lost a tad of compression but was given aluminum heads. The hp rating was 425.

The LS5 continued on into the mid '70s in Corvettes (1974) and big cars (1975) with iron intakes and Q-jet carbs. The LS6 was a 1970 and 1971 only engine but was available over the counter from GM parts for a number of years. The LS6 name was again used later on a crate big block that was available in modified form from the original engine with 425 horsepower until the new LS1 series of engines came out. Then they used the LS6 name for the Z06 SB2 small block engine. The former LS6 big block crate engine is now known as the 454HO but this is a different beast than the early LS6.

As was said above the big block was not available in the the '81 Corvette. 1974 was the last year.

Tom

 

[Peer81]

If you have a 454 in the 81 I would worry more about the weak 81 alu diff that what kind of 454 it is

Greetings Peter.

 

[Vettehead Mikey]

If you can tell us what is stamped on the small pad on the block directly in front of the passenger side cylinder head (should be two sets of letters and numbers) we can help decode what car the motor came from.

 

[nsarvis]

More info

If you can tell us what is stamped on the small pad on the block directly in front of the passenger side cylinder head (should be two sets of letters and numbers) we can help decode what car the motor came from.

There is nothing in the front of the engine but on the back it has GM1 D6/70 3963512 it has an old aluminum intake and a 4 barrel Carb, this car was modified from the dealer in California in 1981 by a Company called Flint Corvette. As far as I can tell not much has been changed since then, I'll throw a picture of the car in here, you can see that it has a costom hood to allow for the height of the engine, Thanks for every ones help, but i'm still at a loss

 

[Vettehead Mikey]

The 3963512 casting number was used for both 427 and 454 cu in engines across all engine lines at GM, including full size cars and trucks. The date code might mean that it was cast in 1970 and is a 454.

Since there's nothing on your stamping pad, this probably means that the engine has been rebuilt at least once. Without tearing it down, there's no real way of knowing what it is/was.

 

[22229stingray81]

Does anyone else notice that his car is also a convertible?? Quite a custom car you got there.

-Tatortot

 

[Tom Bryant]

Yes. It's been a topic of interest lately. A real beauty.

Tom

 

[22229stingray81]

Indeed it is! Thanks for the link.

-Tatortot