Mack'sZ28

Why are alot of people going with the 5.3 heads instead of ls1 heads?

Fast SS on TNT

iTrader: (1)

Higher compression ratio. More power (insert grunt).

Extinct SS

What does the compression get raised too??

Mack'sZ28

Isn't cheaper to get the 5.7 heads milled?

Spellbound

You can mill them, but your push rod length will be affected by how much you mill. With the 5.3's, you can get the compression without milling and keep your stock length push rods.

mike m

iTrader: (6)

plus 5.3 heads out flow the 5.7 heads.

jrp

iTrader: (16)

how is that when the ports are the same? most everything i've seen show the 5.3's and 5.7's flow the same with a comparable port job. only thing the 5.3 has over the 5.7 is the 61.1 CC for the added CR.

Mack'sZ28

How much does 5.3 heads run?

M6HuggerSS

stage 2 heads at PATRIOT are only $1,295.00 And thats a complete CNC port job, there double gold springs, 2.02/1.57 valves, titainium retainers, and new viton seals!

Tally TransAm

iTrader: (17)

you get higher compression with less milling so you can keep maximum p-v clearance

Flyer

iTrader: (1)

I've got a spare set I'll trade someone. Stock for stock. I wanna lower my compression, so the ls1 heads would work out good for me.

FYI, it moves the 5.3 from 9.5:1 to ~9.1:1

JZ'sTA

iTrader: (23)

A few headporters I have talked to say the 5.3's flow a tiny bit better after they finish them. The difference is very little (1-2cfm's from what I gather) Also a stock LS1 is 10:1 CR by adding the 5.3's you will have around 10.8:1 CR. Also you can add a bigger cam because you dont have to mill the heads for the added Compression.
If lower compression is what you want you need to try and trade the 5.3's for the 6.0 truck heads. The 6.0 heads will take a stcok LS1 from 10:1 down to 9.4ish:1 CR. Works greak for the FI guys wanting to run 10psi. Plus the 6.0 heads are better in almost every way then the 5.7 LS1 heads and the 5.3's

FASTONE

Whats the biggest valves you can put in 5.3s, I know you have to put new valveseats ,can you put 2.05 and 1.6s??Bore will be 4.030 also are 5.3s 61cc,s?How much can you mill a 5.3?

WS6 #3392

I love the 5.3 heads. They flow 300 cfm at .600. TEA is the place to ask the questions about what you can do with the 5.3 heads. Look in my sig and you can see what I got with them.

Eastern Bowtie

What kind of numbers can be obtained with a pair of ported/polished 5.3's with big valves and all the right hardware. Matched with the right cam and long tubes of course. Is 400+ RWHP unreasonable?

Tally TransAm

iTrader: (17)

400+ is easily obtainable, people are getting upwards of 430-440 hp. a few might be over 450 but not sure

tea, as, patriot all offer nice 5.3's

ls1/7

iTrader: (2)

if you go with a nice size cam and a set of stage 2 5.3 heads will it be ok to spray like 150 shot on that compression? i know ill have to retard the timing just wondering if it would be ok

bigoneZ28

Good question..I would like to know as well.

JZ'sTA

iTrader: (23)

Will be fine as long as you can get enough fuel. (injectors/pump might be needed)
93 octane would should work just fine.
People have been milling 5.7 for forever and spraying. Many people spray the LS6 heads which are 10.5 CR the little extra compression wont hurt a thing.

black99ta

iTrader: (1)

I was thinking of putting 5.3's on my TA. Can you still run pump gas with the 10.8 CR (with a stock cam)? Does anyone know what kind of power is added by just adding 5.3s?