hey guys i have a 5.3 with a whipple and i was wondering which would be better ls1 heads or 6.0l heads and how would they effect the compresion?

 

6.0 heads have a 71cc chamber and will give about 8 to 1 compression with a 5.3 block,while ls1 heads have 67cc chambers compared to a 5.3 head with 61cc chambers.The ls1 heads shoud give around 8.6 to 1 compression with a 5.3 block.Both the LS1 and the 6.0 heads have a larger 2.0" intake valve compared to a 1.89" in a 5.3 head.The 6.0 317 casting has porting similar to a LS6 head and will out flow the LS1 head.That being said,unless you really plan to turn up the boost really high and go with a big cam I doubt that the increased flow would make up for the lost compression.Plus the 5.3 has a smaller bore that partially shrouds the 2.0" intake valve negating part of it's advantages.You may do just as well to stick with your 5.3 heads.

 

Yeah I would stick with your heads...

I thought about putting 317's on my truck, but like whitt1 said, Unless your planning on running like 16psi or something up there then its kinda pointless..

Plus without alot of boost that low compression will make the truck run pretty shitty!!

 

thanks for all the advice but i got one more question if i intercool my 5.3 how much boost can i run with 9.5 to 1 compression

 

safe or unsafe?

 

Im running 8-10 psi intercooled with twin turbos, on stock bottom end 5.3 with stock heads!!!!!

I dont know if I would run much more than that though.... Maybe with a really good tune and some methenol somwhere between 12-13 psi... But thats pushing it!!