8banger

iTrader: (16)

Hey everyone. I'm thinking of doing some minor heads over the summer. I don't want something that has insane flow...I'm not looking for like a Stage III LS6 or anything. I just want a little bit more airflow and perhaps some higher compression. That's why I'm thinking of getting some stock 5.3's and changing the valves out for larger ones and leaving them unported an seeing how that goes. I figure the valves would increase flow a little and I'd still have the higher compression, therefore adding some power without spending a lot of money on portwork....yet. Good idea?

ssheets

iTrader: (1)

For what you're doing, you might as well just mill the 5.7 heads down about 0.025" and use a thinner 0.040" gasket. That should (roughly, before I get schooled on CR and chamber sizes ) put you around 11:1.

That would get you the same effect and you wouldn't have to change the valves...if 2.00" intakes are OK?

I'm doing similar with the 5.3's I'm trying to also acheive 11:1, but I'll be going with 2.05" intakes and custom porting and chamber work. I'll be installing the heads with a nice new cam, possible an F13 or F14 or the Thunder Racing 230/236 stick.

8banger

iTrader: (16)

Hmmm, didn't think of that. Would they flow any better after that?

Blue02Ws6

iTrader: (3)

Do a search on "home hand porting". You would be amazed how many people ask the same thing over and over.

ssheets

iTrader: (1)

I understand that the 5.3 and 5.7 heads have the same port design. The 5.3's obviously have smaller valves. You said,

"I just want a little bit more airflow and perhaps some higher compression. That's why I'm thinking of getting some stock 5.3's and changing the valves out for larger ones and leaving them unported an seeing how that goes."

So if you took 5.3s and left the ports alone and added 2.00" intake valves, you basically have a 61.37cc LS1 head. You would be somewhere around 10.9:1CR, but would have the same port flow as your LS1 head. That's a lot of work to just get a nice compressin bump. You could get the same net result by shaving your stock LS1 heads.

That being said, if you are going to port the runners too and/or if you want to go larger than 2.00" valves then I'd go with the 5.3s as your getting the small chambers for compression and more chamber area to play with without giving up too much compression and not having to shave the heads a bunch which will have to be considered when re-assmebling with respect to valvetrain geometry and pushrod length.

So if you just want to bump the compression a .5 - .9 you can shave the heads a bit (~.012 - .025) and then use a .040" head gasket.

If you want to go all out then get a set of 5.3's or LS6 heads and put in big valves and get them to flow better in the porting too.

There's always about 3-4 ways to skin this cat, some will say only their way works or they have a secret cam or top secret head tricks, but it all boils down to getting the air in, adding fuel, lighting it and afterit goes boom you've got to get it out.

It's not too hard to get the 90% mark of what most mods will do, it's that last 10% the seperates the true artist from the mix...me, I'm still working on my paint by numbers kit.

8banger

iTrader: (16)

Thanks...what I needed to read.

ssheets

iTrader: (1)

BTW, (I think I said this) I'm going with 5.3s and 2.05" valves. The heads will be custom ported and the chambers worked. I'm looking for 11:1 compression and good flow. Still trying to decide on the right cam.

I'm running through Long tubes, race pipes, and SLP catback.
LS6 intake with SLP 345 Blackwing lid. We'll see what happens?