AustinL911

iTrader: (-1)

I've got the stock 5.7L heads on my car now and I bought a 5.3L truck engine that burned oil, for $300, took the heads off of it, and sold the shortblock. So, I've got me a set of 5.7 and 5.3L heads, both of which are stock. I plan on running the G5X-3 cam, LT's and True duals. I also planned on just taking the one or the other set to a local shop and having them ported and larger valves dropped in. But which should I have the work done too? I have all the rockerarms and components for the 5.7s, but nothing for the 5.3's. Should I just sell the 5.3's and go with my stockers? Thanks.

JoSeY

5.3'ls so u get an increase in compression w/out the millin of the heads that could produce p/v problems....the 5.3's...flow w/ported and have bigger valves as good as any 5.7.

AustinL911

iTrader: (-1)

ok, cool. another question. I don't want to have to spend money for new Rockers, cause they're too damn expensive, so will my stock 5.7L rockers, work with the 5.3's?

770Guy

compression = horsepower

AustinL911

iTrader: (-1)

eh? this doesn't pertain the the rocker question does it? I'm sitting here trying to thing how rockers affect compression, but I'm not an expert when it comes to heads, so.....I can't think of any reason they would. But, yes, I know more compression = more HP.

JoSeY

the rockers will fit fine...

Ben R

Most people I talk to say that 5.7 heads will out flow 5.3 heads pretty easily. I would think that milled 5.7 heads would be the best bet, because you would get the CFM numbers and the bumped compression.

Most 5.3 heads I've seen don't even flow 300 CFM.

JoSeY

they are the same casting....u will just need a port job on the 5.3l's....many NA 5.3's in the low 10's an 9's....

Ben R

Then why do 5.7L heads typically out flow a 5.3L heads. Surely something is different.

Which NA cars have 5.3L heads and are running 10's and 9's?


EDIT: Got the 5.3 and 5.7 backwards.

JoSeY

George had 5.3's.....it's all about the valves...u MUST change out the valves to make'em run right

Ben R

George who? Link to info on his car? I'm kind of new to this LS1 stuff.

LS1derfull

I agree 5.7 head will outflow 5.3 without tedious unshrouding in combustion chambers. Why make more work for your self or your local head porter? If he goes too far or is not able to duplicate his unshrouding work than you will risk chamberwall failure or missfire codes from uneven compression cylinder to cylinder. Just mill your 5.7's to the compression you want.

mikey

iTrader: (6)

I'll put my stock compression 5.7 up against any 5.3. I'm not a big fan of higher compression on pump gas. I tune ALOT of packages and none yet have beat ours. Last 5.7 heads and TR224 cam we did put down 441rwhp and 415 lbs/ft Tq. That was through FLP headers and GMMG exhaust.

We are working with Phoenix Performance (SCCA racing) on an LS6 headed package that is going to rock!

PSU_Engineer

Hey Mikey,
That SCCA team wouldn't be Phoenix Motorsports would it??

mikey

iTrader: (6)

Sort of. They are not allowed to port heads so it's not directly for them or their race cars. Joe and I are joining forces to put out some high HP streetable packages. You'll see more on this in a few months.

JoSeY

how hard is it to unshroud the valves...? not very...the only reason ur 5.3's outflowed is their smaller stock valve size...period...and I'm talking George C that's here on the board....you don't want me to go get a buncha back up cause I'll have him and about a dozen other people in here. Trust me I've seen them both work over at MTI (I live about 5miles away) and the 5.3's def. flow....

JoSeY

Mikey...sounds like you have an awsome replicable shop there..and never once did I say either was better....but if ur going big cam use the 5.3s, unshroud the valves and put in some nice 2.02's or use the 6.0L heads and weld'em up to produce a bit more compression...hell....I HAD MTI STG 2 5.7's...I'm not arguing they produce power..hell I madeover 440rwhp w/the X1 and their heads.....I'm saying a lot of people have done it w/the 5.3's as well...just like Chris ARE 360....George C.....I'm not some 16 yr old playing on the HS computer between classes...I have just the tiniest bit of knowledge....

Ben R

Calm down Josey. Nobody's attacking you or your statements. You're being very defensive.

You said that the benefit of 5.3's over 5.7's was the compression that you gain from going with 5.3L heads, even though they're easily out-flowed by 5.7L heads. Why not get a set of 5.7L heads, port them to flow 320ish, and then weld material to the combustion chamber so that you get not only the awesome CFM numbers, but also the added compression from having the 5.7L's milled. Wouldn't that be the best worlds? That would save somebody from having to decide between having 300+ CFM flow numbers and more compression. They could simply have both.

Billiumss

iTrader: (11)

Hey Austin, you can post stuff like that on our board too you know...

Are you going for most HP you can get? Then use the 5.3L heads.

With using that cam, your gonna have to fly cut the pistons...

Are you getting those heads ported here in Columbus? Have they ever done LS1 heads before? If they say LS what?, then you might want to use a sponsor on here. Absolute Speed is good, a bunch of us in the club have them...

Brian Tooley Racing

iTrader: (13)

5.3's !!!!!!