Hey guys, I've been lurking on this sight for a while an finally registered. I just bought a 66 Chevy II, and I'm thinking of possibly building a 4.8 FI engine for it. I know, iknow, why 4.8 you ask. WEll its simple, I'd rather play around wilth a relatively cheap engine before I drop lots of cash into a bigger engine. Here's what I'm thinking and you can tell me what you think. 4.8 pullout, turbo pistons, maybe rods, heads/cam, and injectors and maybe running 10-15psi turboed. Again , I knew to this Gen 3 stuff so tell me if I'm Crazy. I'd like to be around 500hp.

 

i don't think there are too many if any off the shelf pistons for the 4.8l they would have to be custom made.

 

bore it to 5.7
thats cheap, oreillys charges 12 bucks a hole, and you were already buying forged pistons anyway.

 

IMO, take the money you would spend on custom pistons and put it towards a 6.0 pullout instead. They are not that much more than a 4.8 really if you shop around, and then you could make 500rwhp with less boost on stock pistons.

 

If you really want to do a 4.8 turbo, there are a few guys around here with a ton of experience.

Parish8 dropped in a 4.8 to see if he could blow it up with n2o and turbo. I think he made upwards of 500rwhp at 18-20psi. Oh... here's the thread: https://www.performancetrucks.net/fo...d.php?t=245938

8ALTNG also had a big numbers 4.8 turbo build -- he made 547/582 on an STS equipped 4.8 (but is now going to a 408 and a HUUUUUGe turbo)

VanillaGorilla ran a turbo 4.8 (adding more cubes)

kbracing has a 4.8 with an STS

 

4.8 pistons would have to be custom made. It sounds like you are wanting to do something on a budjet. With that in mind get a pullout 4.8 or 5.3 pull the pan and swap out the rod bolts for some aftermarket ones and run your boost levels just fine with a good tune. That chevy II doesn't weigh **** anyhow and it will haul some ***. No need to get crazy with inches and money to have fun in it.

 

I have a set of custom 4.8 piston (Je Pistons) sitting on a table right now. Actually, I have the pistons, rods and the balanced crank all sitting on the shelf. The combo works and the parts are clean. let me know....

 

To get 500rwhp out of a 4.8 you will need to run about 15-18psi of boost. I'm running 10psi on the high side and am in the 425 range. Like the other have said, forged 4.8 pistons aren't easy to come by. If you want to do a budget turbo motor, this is what I'm thinking about. You can take a 5.3 have it bored for LS1 pistons (5.7) and find some LQ9 (6L) or LS2 rods (there a little bit beffer then stock 5.3 rods). SDPC has a budget forged piston kit with flattop forged pistons, moly rings, ARP rod blots and rod & main bearings for $600. Have all that balanced and get a set of 317 6L heads and you will have a nice budget 5.7L forged boost motor. 500rwhp will be easy with a potential of mid 600's I think.

 

don't you need at least a 4.00" bore for the 317 heads?

 

Can you safely run 10psi+ boost levels with just fuel, hardware, and a tune+
Also, whats size turbo should I be looking for?