headed-ws6

iTrader: (34)

I have been looking at 5.3 heads and was wondering how they flow stock compared to the 5.7 241's? I have my 241's p&p'ed but was wondering if I got 5.3's p&p'ed with the smaller cc chamber if they would add my hp?

orangeapeel

iTrader: (18)

It will add power due to raising the Compression Ratio alone. 5.3's are also higher velocity heads in addition to the raising compression to 11:1.

headed-ws6

iTrader: (34)

So I would get more hp if I just put the 5.3's on with a p&p job?

orangeapeel

iTrader: (18)

Yeah, because higher compression alone will net you more power. Just an unported set makes a difference on mostly stock applications.

headed-ws6

iTrader: (34)

I know the valves in a 5.3 are smaller what would it take to get them up to a stock size ls1 head valve, and how much would a p&p help these heads?

orangeapeel

iTrader: (18)

Don't change the valves. You will end up having to get all new hardware. Gets expensive. They will have more machining to do and lapping the new valves in.

Bigger valves do not always equal more power. That is a common misconception on here. Keep them stock.

headed-ws6

iTrader: (34)

could I change them to a stainless valve? and would you recommend P&P them?

Mikey 97Z M6

iTrader: (37)

True, that is a misconception in some circumstances, but in this case I think the ported 241's with the larger stock valves will flow better, and make more power than a fully ported set of 5.3's with their measly 1.89/1.55 valve combo.

Maybe I'm missing something here, but it just seems pointless to port a head with that small of valves and not replace them with larger ones. ?

Mike

SUTTERERMAN85

iTrader: (42)

arent the 5.3 and 5.7 the same intake runners? just with with the smaller cc and smaller valves? FWIW gunnar at PP was going to put stock LS1 valves in my 5.3 for no additional cost other than the cnc'ing. he said it was part of it. just letting you know what i know.

orangeapeel

iTrader: (18)

Dude. I thought that you had 243's?

headed-ws6

iTrader: (34)

so if they have the same intake runners they would almost flow the same as the 241's and raise the compression which would give me more hp in the end even if they werent ported?

KingSS

iTrader: (1)

I think TSP has come out with a new port for the 5.3 castings. With the 220cc runner they got them to flow 314@600. They tested the heads on a cam only car and picked up 62 rwhp. 460 though an LS6 intake isn't too shabby if you ask me.

https://ls1tech.com/forums/dynamometer-results-comparisons/604283-all-new-prc-stage-2-5-5-3l-head-results.html

headed-ws6

iTrader: (34)

Well I was kind looking to get some on the 5.3 truck heads and get the work done to them. its kind of a budget think. which I know is know way to build LS1.

Zach@Texas-Speed

iTrader: (7)

If you send us the 5.3L heads we can do the porting and valvejob, it should save you some money from having to buy a new casting. If you are interested let me know!