Hey Everyone.

Ive got a set of 716 casting 5.3L w/ a bowl blend done on them.

Trying to determine if i should use these heads or go for some 241 castings.

Here's my motor spec's:
'99 LS1 shortblock
TR230 cam
Stainlessworks LT headers
LS6 intake

Im trying to make the car a good cruiser, make about 380+ Rwhp, and get some decent fuel milage.

Ive got the 5.3 heads now, is it worth selling them to go for 241 castings? I really dont want to buy any CNC heads, or LS6 heads.

If it means ill make 380rwhp w/ the 5.3l and 385 w/ the 241 heads i wont bother, but if its a 10+ rwhp difference, then i might as well

All help greatly appreciated.

 

I would not expect to see more then 5-10hp from a swap like that. The nice thing about the 5.3l heads is they will have a smaller combustion chamber which will give you more compression yielding more torque.

 

Are the stock size valves still in the 5.3's?

 

I'd use the 5.3 heads, have them milled as much as you can get away with before having to flycut ($50), and cut for 2.00 / 1.55 valves ($24). That way you can use the stock valves out of a set of LS1 heads that you could probably get for $25-50 depending on your shopping ability. That'll let you work with what you have and work well on a budget.

 

I dont think id want to mill them, but would my machine shop just cut my current valve seats for the new valves?

If its only going to cost me $100 to have the bigger valves in my 5.3L heads and i would have higher compression so more tq. then id definately be willing

 

^ Why would you not want to mill them? That's just giving up power. Yes, stock 5.3 seats will go out to 2.00 / 1.55 and they'll give you an increase in flow.