Why do you prefer the 4.8/5.3 for turbo builds? Better mileage out of boost?

 

6.0L block would be the better option in my opinion. The 5.3 just can't take much bore + boost, especially for an 800hp goal. Walls just get too thin. That, coupled with lack of availability for GOOD forged pistons <3.905" makes for a tough build. If you plan to make 800hp, I would stroke a 6.0L block to 408c.i. and work from there. You can get NEW 6.0 blocks for $899 plus freight at this GMPP dealer I know of! They keep them in stock!!

 

Cheaper short blocks would be my reason.

If I was going to replace any internals, it would be the rods and pistons. I'd maybe cut the heads for bigger valves. I'd stick with a trailblazer ss manifold.

My main focus would be on the turbo sizing, boost cam profile, fuel system, and a transmission that can handle the power.

Nothing wrong with shooting for 800 to the wheels. I think you should research was some trucks run with 100-200 rwhp less.

 

why bore it out? wiseco make a piston that is bearly over bored. leaves you with thick walls and smaller motor that loves turbo's. again, you don't HAVE to stroke to get big power. if a 1.6l honda can make 800hp i'm sure a 5.3 can do it too. yes i know they rev to 9000 rpm but with over 3 times the displacement you don't need the rpm.

 

You make good points. Boosted applications do love smaller stroke. I must have read through too fast or just assumed he was looking at boring the 5.3, which on a boosted application isn't the best idea, as you could agree. Now with stock cubes, either way would be good route. Cost probably being the deciding factor as 800 boosted fwhp from either block is quite obtainable. Considering cost in this particular case, the $275 5.3 looks to be the better option. I retract my previous statement!

 

Not to rub salt in your wounds but Weisco does have off the self forged pistons for th 5.3/4.8 bore size. Certin Sponser cary them in stock. I have had good luck dealing with SDPC while other sponser just want to pimp there products... I will just leave it at that....

 

I would buy a 4.8 before considering the 5.3 if you dont need the displacement. The 4.8 is superior to the 5.3 for a turbo app. The question that really needs to answered is what are you going to be using the truck for and how much do you care about your power under the curve. The truck is gonna run hard at wot regardless of what you go with, but the 6.0 will obviously be the more spirited setup for daily driving. Ideally I would like to swap a 6.0 in for my 5.3 in the dd and pick up another rcsb 4.8 to turbo and play with.

 

4.8/5.3 are the same bore. They have a different stroke and rod length. The pin height is the same for the piston. The shorter stroke in the 4.8 is what alows it to spool faster.

The Ideal candidate would be an 05 up short block because of the floating Pins and coated side skirts on the pistons.

If some one has a good short block for cheap, I wouldn't pass it up because some said it wasn't the right thing to get.

 

Im interested to know how a reduction in displacement increases spool time. Also, I was under the impression that the crank was the difference in the engines not the rods. Regardless, its the difference in piston to rod ratio that makes the 4.8 superior for high boost and resistance to detonation.

 

Give me a second to get the info for you.