I'm not sure where this 370 comes from other than taking a stock 6.0L and boring it over .030" to clean up the cylinder walls. Many have done this, so have I. I don't see where a 4.8L could become a 370 unless using some odd-sized piston. I think the 370 is strictly referring to the 6.0L block. If you leave the stock 4.8L bore alone at 96mm, then with a 4" crankshaft you're left with a 359 cubic inch motor. That would be a 5.88L with some awesome torque being how small the bore is. It would be like stroking an old school 305 into a 340...torquey S.O.B., but no power after 5000 rpms. Plus I don't see the 96mm bore having many piston options in the aftermarket stroker kits. The LS1 specs would have a wider selection of compression ratios and piston material types.

 

Yeah 5k rpms is enough... I am going to run the vic jr with a 650 or 750 carb setup, so i need something that will handle 6500-7000k. I like that idea though....

So here is the plan

bore/hone the 4.8 block to 3.898 (stock ls1) and get the 4" crank that ive had my eyes on... call my buddy at Weisco get my "off the shelf" pistons. And I am guessing the trod length is 6.098"?

My goal is to have this thing built by the end of july so I can take it to the Woodward Dream Cruise in Detroit... so I need to get light the fire under my butt

 

I'd also recommend getting a set of Scat forged rods while your at it. They make some I-beams that are pretty cheap and much better then any stock gm rod. I'd go with the common 6.125 rod with the .927 pin and get your pistons to match. That is the most popular size to get pistons and rods in the aftermarket. I made the mistake of going to use stock rods and got forged pistons for them only to change my mind and I wanted some better rods and had a really hard time finding rod that would fit, where if I had got pistons for 6.125 rods with .927 pins, it would have been easy. I ended up with Maule pistons and Scat 6.100 rods.

 

kbracing96, is the motor in question with the long rods finished or has it been run hard? I'm curious as to what benefits the longer rod would make and how they compliment these motors. I would assume however, that with a 4" crankshaft one can't use the long 4.8L rods simply because there's not enough deck height...I don't know for sure but I would figure the piston would be out of the hole too much for head clearance. Am I right or are the pistons just that short skirted with a really small pin?

 

My motor is a LS1 and is almost done, but Blowchevy has a Iron 5.7 and I'm pretty sure Rex built it with Probe pistons and Probe 6.125 rods. I don't thing there is any way you could ever use the stock 4.8 rods in anything but a 4.8. They're too long to fit any piston and longer stroke crank.

 

well i planned it out tonight with my builder and we are going to get started on the 383. I say that TX Speed has the rotating assembly for 1700+/- . I did find a price of a 4" crank for 970....so if we're thinking pistons/rods/bolts/rings so on would be more than 1700 if purchased seperately so I think the TX Speed deal is the way we are going to go...

 

I agree. Packaged rotating assemblies are proven combinations of parts, and the bennefit of mass production makes the price lower so let the fun begin!

 

I was thinking about the same thing for my 4.8. Im on a tighter budget and i found a crank out of a 99 silverado and the rods and pistons out of an 01 ss all for under $300. I was also thinking about adding the ls6 cam and maybe a little port work. Any thought?