I would like to build a Sy/Ty clone with the lsx motor and came across a 4.8l for next to nothing. After a little research i found that the 5.3 and 4.8 are the same except for the the 5.3 has a longer stroke so the pistons are dished to lower compression. So i was wondering if they would in the 4.8? I would like to lower the compression so the it would be easier to turbo charge and not spend a fortune to do it. I only want 450-500 horse so the stock parts from what i have read should hold up. It will also be backed with the 4l80e and a awd transfer case. With the 35/65 split (50/50 slipping) the stock drive system should also be fine for a while also.

 

Put LS6 heads on it. This is the perfect solution for you. It will lower your compression (61.15cc on the 4.8 head vs 64.45cc on the 243 head) and also the 243s flow a lot better. Win win and you can get them for about $450

 

Hmmm, haven't thought of that.

 

flat tops are better as well...better quench

 

In this article it said that they have a 71cc http://www.enginebuildermag.com/Arti...all_block.aspx (you'll have to scroll down a little). I have read different threads and they all very. Could i use the 6.0l heads they are suppose to have 71cc? Would this drop compression too much?

 

You might not be able to run the bigger heads because of valve shrouding

 

It should be fine. The new 5.3s come with LS6 heads right out of the factory with 2" intake valves

 

I'd just run the 4.8 as is, I made 500rwhp with a small cam and 11 psi of boost on a stock 4.8 motor.

 

As would I. The stock 4.8L sits at 9.5:1 compression from the factory. That's perfect for 8-10psi, just make sure the intercooler does it's job. However, in an AWD vehicle, I would rather start with the 5.3L. They are the same cost, if not cheaper, from most junkyards than the 4.8L and will make 10% more torque everywhere.

 

What size turbo were you running to get that?
What was the redline at and dose it have the same redline as the 5.3.
I know that the 5.3 would put out a few more ponies but i can get a 4.8l for $200 and the 6.0 head run $200-300. So for $500 it wouldn't cost me to much. If i could run the 6.0 heads to lower compression to 8-8:5 i could turn the boost up a bit.