Vortec 5.7 L31?

[Jclgodale3]

Opinions? Pros and/or cons for a mild street engine build? If ok for the build, what would you change on it? Found one with 40K on it and just curious if it was worth building and putting in the vette?

 

[greg75vette]

I believe that's out of a '96 to '99 truck, right? I'm not positive, but I believe they are simply a Gen I block with a one piece rear main seal like the other Gen I's '86? and later. Is it a 2 bolt of 4 bolt main? I think a 2 bolt, but should be fine for a mild build. I'm sure it will need the usual head, intake and cam swap for good power tho.

 

[Twin_Turbo]

Why buy used? L31 engines are dirt cheap new.

They are roller blocks, 1pc main seal. They use self aligning narrow body rockers. A pretty enat engine for a street build.

 

[moose5.7]

Vortec's are great for street and mild strip use. They use a different intake than old SBC's. I put vortec heads on my 84--big difference. The only downside is they cant handel much lift stock--.470" max. Add comp cams beehive valve springs and .100" taller valves and you good for .550"+. They come with 1.94/1.5 valves. The vortec's flow better untouched than earlier heads that are ported. That block is factory Hyd Roller. Thats worth a big HP gain over a flatt tappet cam. To be short, a vortec motor with 10 to 1 comp, headers and the right cam and intake will be an easy 400HP.

If it were me, I'd rebuild it with flat top hyperutetic pistons, LT4 hot cam, and Performer RPM and 750 CFM carb.