piratebaseball

Hey guys,
I spoke with ERL Performance about either sleeving a 5.3 block or a LS2 block for a 427 or 454 build for my 67 Camaro. The person I spoke with said the 5.3 had more meat and people using a blower typically like it better. However, he said that the LS2 had breathing holes and many people thought they made more power in NA applications even though he couldn't confirm it. At this point, I don't have either block so I can go either way. My question is does the breathing hole make that big of a difference and does it have an effect on power?

Here is my top end: Nick Williams 102mm, Holley Hi Ram, Lingenfelter CNC Ported Heads, PAC 1205X Springs, Tony Mamo Spec Cam, LS7 Roller Rockers with Trunion upgrade.

I plan on going NA and maybe run 7-8 psi in the future.

Thanks guys!

KCS

iTrader: (20)

Yeah, it makes a difference. GM saw something like 10hp at the flywheel on the LS6 in comparison to the LS1 block. I've heard of twice that much in larger cubic inch engines.

1989GTA

This ^^^^^

piratebaseball

So in a 427 or a 454 application shooting for 700 hp at the crank, going with the LS2 block over an 048 5.3 block would be worth 20 horsepower.

KCS

iTrader: (20)

That's what people have seen who've tested that sort of thing. The effects are greater with higher cubic inches and RPM.

piratebaseball

Thanks guys! That's the information I needed to know. Appreciate it!

Millenium Z06

Seth told me that on any motor they can drill a hole thru the main web and create a breathing port so it really doesn't matter which block you go with relative to breathability

KCS

iTrader: (20)

That hole isn't very big though. It's the same as what GM does on the LS1 blocks.