evo462

iTrader: (27)

I picked up a set of used 317 heads I am going to be using for my turbo install. Being that they are used, I wanted to have them at least checked out and cleaned by a shop. I was wondering if these heads have any room left in them for greater performance in the way of porting and polishing? I figured if they're going to be at a shop getting cleaned up and it wasn't too much more money, maybe I could get the worked over a bit.

I know they're similar in flow rates to LS6 heads, and I do see a lot of P&P's 243's out there, so I wasn't sure. What does a basic P&P generally run?

batboy

iTrader: (6)

You bet, porting helps, just like the 243 heads.

evo462

iTrader: (27)

I thought I remembered reading there was less material in the runners or certain areas compared to the 243's which made porting them more difficult. I don't even know of a reputable porter in my neck of the woods anyway, but I thought I might as well try to squeeze out every last HP I can.

elias_799

iTrader: (8)

just do it yourself.

what i did is remove all the casting imperfections on the combustion chamber and the exhaust runners and polished them afterwords, the intake runners where not that bad, so i left them alone.

the casting on the combustion chamber was disgusting, it had like little droplets of metal hanging off and that would of created hot spots

evo462

iTrader: (27)

Yeah, I don't know that I trust myself enough to go screwing around with a dremel on my heads. More power to ya if you're skilled enough though!

I guess I wasn't sure if it was even worth the trouble or money. I'm hoping for 525 - 550 RWHP with the 317's, LS6 cam, and MPT70 turbo. In the grand scheme of things, is a P&P job going to net enough extra HP to make it worthwhile?

SweetS10V8

iTrader: (4)

ALWAYS!!!! (see sig)

Ported heads in a boosted application means more power using less boost!

Justus67

iTrader: (3)

The shop my cousin is at actually welds and reshapes the runners then does the p&p. They flow just as much if not more than the 243's. I think they are around 315-330 cfm on the 317's. He is boostfedcivic on here, pm him and he can tell you about it better.

Zerokube

iTrader: (4)

are 317 heads good for a n/a set up with a big cam though? not to jack the thread

evo462

iTrader: (27)

They have larger combustion chambers so I'm gonna say no compared to 243's, from my research, because they'll lower your compression. On N/A...higher compression = higher HP.

elias_799

iTrader: (8)

no, they will lower CR, for N/A motor i would stock with 243's if you are on a budget

Z28SteveA4

iTrader: (16)

what kind of compression will these when give u?? Im just asking because i believe they will give you higher compression then ur stock heads and for boost applications higher compression is not good. How much boost do you plan on running with this motor?? Im not trying to be a dick im just trying to save you money in the long run so you dont blow apart your motor after putting that kind of money in the setup.

02*C5

iTrader: (1)

Your thinking of 799's from 241s, 317's will net you a 9.5:1 ratio with no milling done to the deck. 317s are the bets head if you are on a budget, as it is they flow close to 243/799 and yet they have great potential if you get them to the right hands to port and polish them.

You out fit them with LS6 valves and you have a hell of a valve train set up for boost and high rpm, application.

elias_799

iTrader: (8)

with 243 on a ls1 with stock size headgasket it will be 10.6:1

with 241 it will be 10.25:1

higher compression does not necessarily mean that it is going to blow apart a turbo motor , it is the wrong fuel that destroys high CR turbo engines

02*C5

iTrader: (1)

You can have what ever compression you want with a FI set up what makes the difference is the fuel. You can run an e85 conversion and make 600+ rwhp on a t76 set up on an LS1 with 243 heads. Seen it done, and ran great.
People like lower compression because you can run more aggressive timing & tune than with higher compression and use 91 or 93 octane than having to go with 100+ octane on every fill up.

The word of the day is Detonation

That is the dirtiest word in a engine builders vocabulary.

orangeapeel

iTrader: (18)

Unless you are a diesel engine builder.

02*C5

iTrader: (1)

Hey

elias_799

iTrader: (8)

that is why i have a 8.6:1 CR motor i do not even use meth

orangeapeel

iTrader: (18)

I hear its hard on your teeth.

evo462

iTrader: (27)

I wish there was e85 stations around here, but there's none...the best I can easily get is 92 octane, hence the lower compression.

Kris Mess

I just know I pro charged a 05 lq9 with 317 heads .. I'm guessing 10:1 and a 03 Zo6 cam .. tuner said it choked at 5k rpms making 350hp and 400tq with 100% .. asking for a safe tune .. my brother has twin turbo at 7 pounds also with a ls2 and 317 heads running 9.5:1 100% gas and maxed out the 60 pound injectors a little over 700hp .. so I at least know them heads can flow 700hp , just not sure what my problem is .. porting heads help that much? or the cam? .. he's even running less timing that I am .. kinda baffling to me