COMNBYU

Did a search but couldn't find anything. I'm sure it's been asked a billion times but....


Will 5.3 heads fit/work on a LS1?? I've heard yes from most people.


Any modifications needed?
Is it worth it?
How much power gain would be realistic?



Just know where I can get a set of 5.3 heads cheap and am wondering if it's worth it.....











TIA, Jon

ty_ty13

iTrader: (42)

http://www.totalengineairflow.com/

check there for 5.3 heads..

COMNBYU

Thanks for the link, but I was more or less wondering if I bolt a set of stock 5.3 heads on a LS1 would that be sensible?? Better/worse?? Will they fit???


I already know where I can get some stock 5.3's cheap...









Jon

blkZ28spt

You should be able to find more by searching.

You can. The 5.3L truck heads have a smaller combustion chamber that increases the compression ratio. LS1 heads flow better than the 5.3's though, so I'd only put 5.3's on if they are nicely ported. Watch the PTV clearance if you cam it.

ssheets

iTrader: (1)

They are the same heads as far as ports go, they have smaller intake valves and the cumbustion chamber is about .030" loer giving the chamber a 61.37cc volume vs the 66.67cc volume of the 5.7 LS1 head.

The advantage is the smaller chamber without affecting valvetrain geometry. Throw in some bigger valves and you've got got the same or better heads than your stock running about 10.9:1 all things being equal.

...I've learned most of this in here so I'm not sure how hard you researched.

I'm currently building a set of 5.3s with 2.02" Manley Pro-flow valves and PRC gold spring kit. I'm trying to squeeze in a Futral F14 cam which is going to be tight for PtoV clearance. I'm trying to go with a 61cc chamber and .042" gaskets for an 11:1 compression ratio.

silverTA2002

iTrader: (1)

Would it work? Sure.

Would I bother taking the entire engine apart to put a set of unported heads on MY car?

Definitely not.

If you're gonna change the heads, at least get a ported set.

ssheets

iTrader: (1)

Yes, since they have smaller intake valves the net advantage of increased compression is negated in a direct swap.

However, for a normally aspirated LS1 the 5.3 heads make a great foundation. Keep in mind that most performance increases on LSx heads are gained in the valve job and unshrouding. The ports need very little work, actually you can do more harm then good by messing with them unless you know what you are doing. The stock seat material is supposed to handle up to 2.02" valves, although we opted for new seats to be on the safe side.

So, if you can find a set of 5.3 heads, have a quality valve jod done on them you'll get better flow than stock (based on the valve work alone) and about a .6 to .7 bump in compression ratio.

So like I said, "a good foundation" for a budget normally aspirated motor. Throw a nice cam into the equation and the increased compression will really start to show benefits.

In simple terms, the 5.3 heads are just lie 5.7 heads with the chamber ceilings lowered (the reverse of milling the head surface) .030". If you are looking for a way to get your LS1 into the 11:1 compression range with stock pistons you either have to shave the heads down .025"+ (yeah, there's a plethera of gaskets out there) and then worry about valvetrain geometry or go with a set of 5.3s.

COMNBYU

Thanks a bunch SSheets!








Jon