UUHH no they wont. Ported 241's are not on par with ported 243's. Where do you get your info from? If you think a 241 chamber mimics a 243 chamber you are totally misinformed in what you have read on the net. The 243 combustion chamber is superior over any 241 or 317 cyl. head. A ported 241 engine is not the same as a ported 243 engine. The combustion chamber is everything.

 

241 casting is so 1997 technology lol. Its lame, same as the 317 is. At least the 243 has MAJOR updates to the combustion chamber. It is absolutely superior. Its like the dopes that say a 5.3 head is the same as a 243 once ported lol.

 

You do realize a 317 head is the same casting as a 243 just with a larger chamber to lower compression right?

 

Did you not see the threads I posted of AI's ported 241's making killer power on numerous setups??? One of them is from username Damian, who knows more about this stuff than you or me could ever dream of knowing. Read his thread where he basically puts the whole "241's can't make killer power" myth to bed and then come back and spout off some more. I never said ported 241's were better than 243's, but there isn't that much difference. You need to quite believing all the horse **** you read on the internet, do a little bit of research like I did, listen to LSx experts like Damian, and quit acting like you know what the **** you're talking about because you don't know jack ****. Anyone who says a 317 casting is **** and a 243 casting is gold should refrain from posting in the big boy threads and go hang out in the racers lounge with the rest of the clowns.

 

Hey man, I agree that non-243 heads can make some great cars run fast...really fast.

BUT GODDAMNIT SOMEONE GIVE SOME KIND OF QUANTIFIABLE DIFFERENCE BETWEEN LS1 AND LS6 HEADS FULLY PORTED!

Please a decade later what's the damn difference? How much to gain?

All input so far is valid and appreciated but holy **** what is the difference in full-out potential?

I am sure someone will bust my *** for seeming like a dick about this but I think we owe it to ourselves to come to some kind of standard.

Thank you for all of your input and taking the time for me to bitch.

 

There really isn't a right or wrong answer. In a all out NA race application, the 243 castings are best. They've gone the fastest, to my knowledge, in SAM's orange Camaro like 10 years ago. I believe it's because the port is more critical in those applications.

In a street application, which mostly have stockish sized valves, relatively low .600" lift hydraulic roller camshafts, and plastic manifolds, the differences between the heads (mostly in the ports) are not as critical.

A really good cylinder head guy once told me that in these applications, you could takes 10 sets of heads ported by 10 different guys, and if they all have the same valve size and same valve job, you won't see much more than a 10hp difference on the same engine. It's like the old school guys (like David Vizard) have been saying for years, 90% of your gains are in the valve job and 1" above and below.

 

You're over thinking this. If all you are looking for is a fast *** street car that you can run at the track, then it really doesn't matter which heads you run. Since you have ported 241's already, run them and focus on getting a custom cam to match the heads and rest of the combo. If you are dead set on the best heads, then look at some TFS, MAST, PRC, AFR, etc. Since you're on a budget, likley those are going to be out of your price range. If you're so concerned about chasing a number, just dyno the car on a well known high reading dyno and call it a day. A car running ported 243's may make 415rwhp on dyno "a" and your car may make 440rwhp with ported 241's, but if you line both cars up at the track and your car only traps 112mph and his car traps 130mph, well, then you see who's making more power. Just a scenario I'm throwing out.

 

Seems to me that comparing cylinder heads by using chassis dyno numbers is like saying Cherrios equals a 6 minute mile and Wheaties is good for a 5 minute mile. Way too many variables.
I'm an engine guy only and have devoured every ounce of small block Chevy info for at least thirty years, however I' m admittedly new to the LS world. I've owned a few trucks w/some mods and my Vette is by no means fast.....IMO
With that being said my guesstimate of the LS6 making 55 more HP than my Vette LS1 would be 5 horse from the compression increase, 25 from the camshaft timing, and 25 from the heads.
Obviously the difference between 241/243 castings gets much closer when someone like A.I. works them over and the HC treatment primarily targets the combustion chamber by welding it up and reshaping it to both improve the breathing as well as the combustion efficiency (flame propagation).
The one glaring difference that can only be enhance but not corrected is the floor aproach and short turn radius of the 241. It's just not shaped as well as the 243/799/317 castings.
The general admitted to corresponding with Lingenfelter who was already CNCing 853/241 castings in order to correct/improve the casting for the birth of the 243s.
If the OP is on the "I already have these" program then it seems he's got some darn nice heads and should run em'.
If he wants the most from a GM casting then we already know he needs to start with 243/799 versions and pick your porter.
Max effort in my opinion means MAST, TF, AFR, or PRC....definitely more money but certainly more power as well.
If I was forced to speculate what the engine dyno horsepower difference would be from AI HC 241s to AI 243s; I'm saying minimum of ten and a maximum of fifteen. Totally up to you of it's worth the price.

 

Thank you for putting up a number(range). Sounds like "max effort stock ported head" build might be worth the 243 as a starting point. I've got a set of both and since I probably won't ever see a dyno, I'm likely to sell the 243s and put that money into porting the 241s. I can get good money for the 243s and most folks don't want to cover the shipping on used 241s.

 

Just make sure you maxamize compression for your setup. A good bump in compression is worth quite a bit of power.

 

Right. Forgot to mention that. Would mill the 241s at the same time.

Thanks.

 

Ported 243's at 63cc compared to ported 241's at 59cc on the same setup would likely mean more power out of the 241's. Just another thing you have to add into the equation. All about the combo.

 

That was an interesting read. That is the magic that makes the difference between a lot of flow and a lot of flow /with/ a lot of power/efficiency.

The mention of their intake "wing" reminds me of the threads asking about the beleaguered swirl ramp.