Ok, so I'm gona build a new motor for my truck. What I'm wanting to do is build an iron block 347 out of my 4.8. This will be a turbo motor too. Here's what I have, the block that's currently in the truck 4.8/5.3 bored out to 3.898, a crank out of a 6L, a set of ls2 rods and a set of 317 6L heads. I figure with flat top pistons this will put me in the mid to low 9's for compression with stock gm gaskets.

This is what I'm looking at for the pistons. Anyone have any experience with these piston kits from SDPC? Are they any good? I will have the rotating assembly balanced and will be using ARP heads studs. I also plan to run this combo up to around 13-15 psi of boost. Think it will hold up? Sound like a good budget, forged FI motor? Please let me know your thoughts.

 

It looks like the kit uses Speed Pro pistons. I have heard good things about their rings, haven't heard anything about their pistons. I would research what alloy they use, the 2014 (I think) has a lower co-efficient of expansion which makes it better for high heat/stress applications. Also, they come with metric ring grooves. I have heard that the standard ring grooves are stronger (1/16 1/16 3/16). Hopefully Rex will find this post and give his opinion/experience.

 

If you are going to do this,I would highly suggest you put good rods in the engine. Stock rods are OK for A while but they do fail. To answer your question about the pistons as long as they are forged they will be fine. And yes, the 1/16 1/16 3/16 are much tougher than the metric rings,although I have used many metric ringed pistons with much success. You must pay close attention to ring gaps and piston design or your engine will drink oil. You need A piston that only requires minimum piston to wall clearance say .0035-0045 A street type forged piston. They are plenty tough for most applications. Rex........

 

Thanks Rex, I was hoping you would chime in here. Do you really think that after market rods are necessary? I chose the LS2 rod, cus there a bit beefier then the stock rods and have the floating pins. This is mostly going to be a daily driver, I just wanted to get away from the short stroke of the 4.8 and build something to get some low end toque that the 4.8 lacks and be a bit stronger then a stock motor. This current motor has stood up to 40k boosted miles with out problems and I run it pretty hard. The truck is a dog under 3k until it builds boost. I only plan to spin this motor to about 6200 as that all the cam I have (Vinci ultra torque) and the current motor make about enough power for me at 10psi, but could always use more, lol just want more low end and a dependable mid 12 sec truck. Am I on the right track?