I think the bottom end is good. Motor has 40K on it. I'm thinking of boring it out to LS1 specs and going with forged pistons. I'll probably use the stock crank, but I'm wondering about the rods. I don't plan on spinning it past 6K. I'll leave the blower pulley at 3.1" and the cam that's in my sig. I'm thinking that boost will go down, but power will be up. Also considering the 90mm J tube conversion.

I'm wondering what to do about the heads. Know I want to change them, but wondering which way to go. Would 6L truck heads be the ticket, or would you go with LS1 or LS6 heads? I'd like to keep CR around 9.5:1. I don't want to spend a bunch of money on ported heads because I don't believe they will be a good bang for the buck on my setup. Your thoughts appreciated.

 

From what I understand, the hot ticket is 317's because they flow the same as LS6 heads and they are 72's allowing more boost.

 

I'd go with the 317 cast 6.0 heads. As for Rods at least do ARP bolts. Also Hit up Rich from WCCH about his rods.. If you have the 400-500 bucks, it is worth getting rods, plus you can get them in 6.125 and have a touch longer rod.....

 

I would go ahead and do the rods. For $390 shipped, its worth it.
I would do the 317s if you want to do a good budget head.

 

Building a 6.0 may be a good idea also, if you can find one. You need the heads anyway, and the rest of the engine cost the same, and your machine work would be a little less. I wouldn't trust the boared out 5.3 for a boosted app. I know guy's get away with it, but with my luck I wouldn't.

 

iron 347's (bored out 5.3's) are widely used and can make big horsepower even with a few less cubic inches. Check out ls1tech in the FI section. There are people making 800plus with it. Even with the 3.90 bore, it has plenty of meat left in for stability.

 

alot of people are using boring out the 5.3 to a 5.7... do a search here, blownchevy is one of them I believe...

 

Is there any advantage going to the 6.0? I think my blower will be about maxed trying to satisify 5.7. Am I about at the limit of what the 112 will feed effeciently? I've been told that I can make a little more boost, but a whole lot more heat by going with a smaller pulley.

My son has a bored out 5.3 (to 5.7) with a Trick turbo setup that's running too good. Just got it back from the tranny shop. Twisted the output shaft in two (on just 6psi).

 

Contrary to popular belief, the Radix 112 can make good power on the 6.0L effectively however it will show its limit. I would think the 112 on a 5.7L would be a nice complement to each other with the correct cam. And I wouldn't hesitate to strap on a 2.9" pulley. I run the 2.8 on a 6.0L and have nothing good to say about it.

So, what did you do the 5.3L again to require a rebuild?

 

I don't know if it just got tired of 9psi or possibly the boost cooler quit. The light on the boost guage came on at 6psi to indicate it was working, but I have no way of knowing if the fluid was actually getting to the motor. AFR has been right on. Right now it has 150 to 170psi on cylinders 1-6. #8 has 0 and we didn't check #7. I'm guessing #8 piston is trashed. Haven't pulled the valve cover off to make sure the valves are moving, but I think that's a long shot. Have I missed something? Truck has 18K on it when we added the mods. Now has 40K. I don't beat on it constantly, but do like a full throttle blast from 30 to 80 on occasion.