anyone know the difference in stroke between 4.8 & 5.3 motors, also I'd like to pick up a used 4.8 crank if anyone who is doing this swap wants to let their old one go for cheap, I'm trying to build a higher RPM motor for a kitcar swap and don't know but I think I can drop that in a LS-1 alum block....

 

One thing to consider is that you could probably find a stock 5.7L LS1 rotating assembly just as cheap as a 5.3 rotating assembly. Just think how many LS1 guys go w/ forged rotating assemblies. Take the iron block out to 3.905 and make an iron 346 for just a little more than making a 325.

 

Stroke: 4.8 = 3.27". 5.3, 5.7, 6.0 = 3.622"
Rod : 4.8 = 6.278". 5.3, 5.7, 6.0 = 6.098"

Anyone have the weights of the various piston?

Andy1

 

so what combination of parts makes the short stroke motor i want? stock crank which are all the same and the shorter 5.7 rods ? I'm totally confused now?? whats the difference in bore size? believe it or not I'm trying to build a motor that will run to 7kRPM reliable and not have alot of low end TQ???

 

If you want a seriously oversquare engine the 6.0L block/pistons with the 4.8L crank/rods would be the item. 6.0L bore = 4.00", 4.8/5.3L bore = 3.78".
Or bore out the 4.8/5.3 block to 3.898" ( stock 5.7L size ), use 5.7L pistons, and the 4.8L crank/rods.
Again check out the piston pin height on the 5.7L or 6.0L to make sure you would not poke one above the block deck and/or drop a serious amount of compression.
I am pretty sure BigTex/Richard researched all the dimensions last year for someone, try some searches or drop him a PM.

 

Upgrading the bolts in the stock 4.8 it should be able to see 7000 with no problems.

 

Would you have to pull the engine to do this or could one drop the oil pan and swap out the pistons, rods and crank with it still in the truck?

 

Pull it.

 

Is there not enough room between the frame rails or what?

 

when doing this swap your going to wany to pull the motor because you are bascial looking to rebuild the motor. you'll want new bearing's and will have to check tolerances as well as at lest hone the bore's. after all if your going to this work wouldn't you want to take the lest amount of risk and get 200k+ out of the motor? I'm also doing a simliar build for a slightly differnt type of project how ever I'm building a very stout motor with some nontypical theory's.