Racerhoze

I have a 5.3 LM7 with 90k on it, have also picked up a ls6 intake, 243 heads and a GTO oil pan. If I don't want to spend more than a couple grand, what can I do from here that would give me the most reliable power? I know the 5.3 has the dished pistons and I was reading that some were using the 4.8 flat top pistons to keep compression up. I also read that some were using a stock LS1 rotating assembly and having the 5.3 bored to 5.7. I could just get the existing heads ported and go with a big cam like the modern mouse build...

http://www.superchevy.com/how-to/pro...l-block-build/

I am a pretty big LS noob, been more of a BMW guy until now. So tell me what you would do given my budget and current parts!

KCS

iTrader: (20)

I would rebuild it with an LS1/6 rotating assembly. Bore the cylinders and torque plate hone them for the larger pistons. Can't get much more reliable power gains than an extra 20ci from a freshly machined shortblock.

Always2Slow

iTrader: (8)

What KCS said is the cheapest way of doing it. Things to look out for when sourcing parts is scuffs on the piston skirts or the sides of the pistons. If I had to give preference to which setup you would want I would opt for the ls6 setup because it was a full floating setup and would be easier for you to install yourself.

Racerhoze

So you guys would look for a used ls6 rotating assembly? I am not sure if the crank/connecting rods are different 5.3 to 5.7...

KCS

iTrader: (20)

The crank for the 5.3L is likely balanced to a lower bobweight. If you find an LS6 crank, rods, and pistons, you won't necessarily have to rebalance the crank. Other than that, just make sure the clearances are good and that reluctor is right for the vehicle/PCM it's going to and you should be good to go.

Racerhoze

I have been digging around and am not finding much on used rotating assemblies. There are plenty of new, and ones that come pre-balanced... though those are $$$.

I am guessing that if I were to find some 4.8 flat top pistons, that my rotating assembly would need to re-balanced anyway, though going with flat top pistons would limit my cam options as well.

Always2Slow

iTrader: (8)

Going with flattops wont limit your cam options unless your doing something ridiculous with this thing.

garygnu

buy the cam last ! consider a 383 ls stroker rotating assembly .check Texas Speed to get a idea of what things cost .