SPANKY LS1

iTrader: (24)

I have a few questions about 5.7s -vs- 5.3s and I'm too lazy to search. Both flow the same, the only difference is compression, correct? For example, a 5.7 head ported and milled .030 should produce roughly the same power as 5.3s unmilled but ported identically, correct? The advantage that 5.3s have over 5.7s is that a 5.7 has to be milled to obtain the same compression that an unmilled 5.3 head does, right?

Thanks, Shawn

SLowETz

iTrader: (12)

stock vs. stock

SPANKY LS1

iTrader: (24)

Ok, take a ported 5.7 and a ported 5.3 from the same company, the same size valves, springs, CNC program (for consistency, we'll use TEA, PP, or another "CNC" porter). Will the 5.7 flow the same and produce the same power as the 5.3 head, if the 5.7 is milled to make up for the difference in compression that the 5.3 has?

Are/were your heads 5.3s or 5.7s? The reason I'm asking is I'm curious why everyone is leaning towards the 5.3 heads so much, you rarely ever see 5.7s being used anymore, and I was under the impression that both flowed comparibly, the only (main) difference was the added compression of the 5.3.

Pro Stock John

iTrader: (34)

5.3 heads have a smaller combustion stock than 5.7 heads.

taqwache

also stock 5.3Ls have smaller intake valves then stock 5.7s and need to be upgraded.

SPANKY LS1

iTrader: (24)

I know that the chamber is smaller. What about flow and power? Is the only difference the chamber size (compression)? Will a 5.7 head that is milled enough that the chambers are the same size flow the same/make the same power as the 5.3? Or are there actual flow/port differences?

SPANKY LS1

iTrader: (24)

OK:

Head A: 5.7 head, (milled to where the chamber size and compression is equal to that of the unmilled 5.3 head), 2.02 & 1.60 valves, CNC ported with the same program as the 5.3 head.

Head B: 5.3 head (unmilled, assume same chamber size and compression as 5.7 head milled .030), 2.02 & 1.60 valves, CNC ported with the same program as the 5.7 head.

Both heads will (theoretically) flow the same and produce the same power, right? (Assuming compression and chamber size is the same.)

Damian

iTrader: (89)

From what Tooley told me, until the 5.3's are opened up they flow less than a 5.7 head...

So theoretically, you would make less power w/ a stock 5.3 vs. a stock 5.7 until they were opened up, cleaned and ported...

Josh

Cal

iTrader: (1)

Another factor is the 5.3's will give you more P/V clearance in comparison to the milled 5.7's.

SLowETz

iTrader: (12)

Given all else is equal, (ie)port/blend/valvesize/shape, they should flow the same # on the same bench w/in a few cfm. Milling the 5.7 will bring up CR, and yield you the 5.3 CR, hence theoretically making the same power even though the chamber sizes were larger before the mill. So....yes, the main benifit to the 5.3 is higher CR w/out the P2V #'s shrinking. Not sure if the material removal areas/blending of the two chambers is different though.

FWIW....Brian is getting as good or better #'s from the stock valve as the aftermarket valve, and the load test results from the stock valve was insane. I had no idea they were that strong. Don't quote me, but I believe Brian will also confirm that for N/A combo's, the stock valve will hold up just as well as the Ferrea, the only benifit being the Ferrea is lighter.

The heads you purchased are '02 5.7L castings. Unless you think yer ever gonna run some donkey dong stick in it, go ahead and cut them and get yourself lil' more CR(it's a good thing )

SPANKY LS1

iTrader: (24)

I'm not gonna use those heads after all

Shawn

SLowETz

iTrader: (12)

LOL!... Casper was right....said you wouldn't stick to the plan for very long.

...btw....got the letter....thanx!