jwatts

iTrader: (4)

I have an LQ4 I am building. Right now I have a set of 317 heads on it. I am wanting to up the compression without milling the heads I currently have. I have been looking seriously at a set of 243s or 799s. Lately I have been seeing a good many 241s for sale, and at a much better price. I was wondering, at what HP level do the 241s lower flow rates become a limiting factor? Would I see enough gains from the increased compression to offset the lower flow of the 241s compared to the 317s?

This setup is going in a 66 chevelle. My goal is around 425-450hp at the flywheel, or 350 or so at the wheels. I want the power mainly in the lower rpm range as it will be more of a cruiser/street car than a track car. I would like to get into that power range as cheap as I can, because honestly if I can get the power I want and save a few dollars I can put that money toward other parts of the build. I plan to hold on to the 317s, because if in the future I decide to go with more power it will most likely be through a forced induction setup of some kind.

I am new to the LS scene, so please forgive the seemingly basic questions.

BlackLT1Z

iTrader: (11)

241s will get you to 350rwhp no problem with a good cam. You can make 400rwhp with stock heads and the right cam.

jwatts

iTrader: (4)

Thanks man. I didn't figure it would be an issue, but I wanted to make sure before I bought a set of heads.

SIC GTO

There's a Gto making 455/397 to the wheels with AI 219cc 241 heads. The power you want should be easy, btw my dad has a 67 chevelle hes restoring right now. Post pics of your car lol

jwatts

iTrader: (4)

I am going to start hitting up a few ads on here and try to pick up a set of 241s then. The car is in the early stages of restoration. Here is a pic of it as of a week ago:



And here it is before I took it apart:

BlackLT1Z

iTrader: (11)

Ya... for $100 bucks or less... you can't beat that.

96capricemgr

iTrader: (1)

The LS6 makes more power than an LS1 and the 243s are part of that.

jwatts

iTrader: (4)

Oh I realize that. But, if I can get to my HP goal cheaper by going with the 241s vs the 243s I figured I may as well. If it weren't for the fact I am still running a 45yr old 10 bolt and my wife will be driving the car some I would get the 243s anyway knowing they would support more power than the 241s if I made changes down the road. That's the reason I am keeping the 317s, in case I go forced induction later on. I haven't bought any heads yet either so I may still end up with 243s.

nomasterase

iTrader: (4)

350 at the wheels should be easily attainable with 241s and bolt ons. If you decide to go with more power later a good port job from our sponsors will get you damn close to whats available from a good aftermarket casting like AFR or Trick flow. Buy the cheap 241s in my opinion

96capricemgr

iTrader: (1)

Where I was going was the 317s have the same ports as the 243s. IMO the 317s should get you your goal without having to buy any additional heads.

Yes I understand the compression is lower. Your goal is quite modest though so I don't think you need to spend a few hundred dollars(not just 241s but gaskets and bolts) swapping heads to raise compression.

I understand the wife driving it thing, my wife has even raced my car, and on rare occasion taken it grocery shopping if I was working on her w-body 3.4l FWD turd.

thunderstruck507

iTrader: (18)

If it were my car I think I would rather shave the 317s I have just a little than drop any money on stock ls1 heads (241s).

The 317s can get you your 350rwhp just as easily if not easier than the 241s and since you already have them theydon't cost you a thing.

Beotch

Nice project, going to be very cool when finished!!!

jwatts

iTrader: (4)

I had kicked around the idea of shaving the 317s. I decided against it in case I decided to boost it later. It's still not completely out of the question though. I am checking on a set of 241s with springs right now. If that doesn't work out maybe milling the 317s may be my best option.

jrob56

iTrader: (39)

Ya it doesnt make sense to me to change em if you only want 350 wheel anyway. You could leave them as is unmilled and hit that with a cam.

jwatts

iTrader: (4)

If that's the case I may just leave them as is to cut down on some costs. Like I said, I don't know a whole lot about the LS platform.

PREDATOR-Z

You can have the chambers in the 317s filled in and therefore reduce chamber size. if you get them to 64cc, you'll basically end up with 243 clones. Advanced Induction does such work.

jrob56

iTrader: (39)

I believe you could easily hit it with a cam, you might be close with full bolt ons. Im doing the same, lq4 into my 01 Camaro. Stock 317 heads and stock cam, plus bolt ons. I dont know if I want to go FI or stay stock, so to me right now its not worth the work to swap anything.

If FI ill leave it alone and throw a frount mount turbo or procharger on it.

If NA Ill slap some ls3/l92 heads on it down the line and get a good sized cam and fast for it.

01ssreda4

iTrader: (96)

As stated, 241s will do what you are wanting. I've got a fresh set of 241s that have been cut .025 if you're interested.

thunderstruck507

iTrader: (18)

If the heads are not off the car and you don't have to take them off for anything, I would slap in a small/medium cam and do bolt ons. With a good tune you will pass your mark easily.

jwatts

iTrader: (4)

I'm pulling the heads as soon as I get the engine fitted in the car. I haven't looked at it internally so I plan to check the cylinders before I button the front cap back on the car. That's one of the reasons I considered swapping the heads out. The old ones will be off anyway, so I will be getting bolts and gaskets regardless.