black06g85

iTrader: (6)

I have a set of 5.3 heads too. might run those, I dunno yet. we'll see what happens.

Bob Niles

Hey I never was much a turbo fan but mostly because of the disasters if improperly installed but i was looking at twin turbo for my 5.3L 2000 chevy silverado 4x4 ls and a cam upgrade possibly new heads. I have headers and flow masters for exhaust and a cold air intake from Is3, monitored with hypertech max what would be a good compression if I bore it out to accommodate the twin turbo and a lil spray

1994silverado

I'm looking to build a 2002 5.3l chevy. I'm going to carborate it and put twin 76mm turbos on it. Bottom end is stock. What heads are best for that? Apparently 317 heads are too low compression? Will the stock heads shaved 30 thousandths work fine? It has 11.1 compression now. How much boost can I run on pump 93 non ethanol?

MY_2K_Z

iTrader: (1)

If it's stock it doesn't have 11.1 cr. Why would you remove the fuel injection. Seems back asswards to me. Twin 76s on a 5.3 is pointless

1994silverado

twin 76s on a 5.3 will actually build about 780 hp.

kbracing96

iTrader: (25)

One 76mm turbo with a 75mm turbine will make 780 hp. Twin 76mm turbos on a 5.3 will be lagggggg city, even with tiny 65mm turbines.

The BallSS

iTrader: (9)

I did some quick calculations and a LM7 with flat top pistons, cometic .040" MLS head gaskets and 317's w/ a 72cc chamber should net a 9.52:1 compression ratio.
Down slightly from 9.8:1 on a LS1 w/ the same 317's.
That reduction doesn't seem too bad at all for a street car and would allow a touch more boost.
Thoughts?

Forcefed86

iTrader: (4)

I think you did your quick math incorrectly. Compression will be lower I'd think.

If a flat top LC9 with 64.4cc heads is 9.6:1. Add 6.5ccs with the 317 heads and subtract a cc or so for the .010 thinner head gasket. You'd around 9:1. If you mill the 317's .030 and you'd be in better shape. I just milled a set and it cost me $75.

SteenH

I also believe you're too high on your calculations.

roastin240

iTrader: (13)

Ha ha I love how specific this is. I wish I had more room in my signature for this post

Dimeomboost

wow I didn't know it was this easy now just throw them on and stop tuning when u see 780hp seems simple enough wonder y the forced induction section is full of new help me with my turbo build threads every day

The BallSS

iTrader: (9)

A l33 5.3 with flat top pistons, .051 gasket and 64.4cc heads is 10.1:1 compression per GM.
Add a .040 head gasket and 72cc heads I get 9.5:1 compression per the calculator I'm using.
What am I missing?

The BallSS

iTrader: (9)

According to GM the bore is smaller and the chamber is bigger??