When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Here is 243 Vs the 241 casting. I recall in older conversations with head porters that the 706 are similar to the 241 casting in port shape. They just use a smaller intake seat and valve.
243 on the left 241 on the right Intake 243 on the left 241 on the right Exhaust 243 on the left 241 on the right Top Veiw
That's awesome fastbrick, I appreciate the post. Even if it is 243 vs 241
Looks like the 241 has a flatter floor that flows into a sharp turn on the short side, and the 243 port floor dips down closer to the intake side then comes back up then has a smoother transition down around the short side to the back of the valve. Interesting.
Because of these talks I grabbed a 799 the other day off a 4.8 that had already had one head robbed. From quick inspection this 799 looks very close to the 243s I have already... The inset area around the valves that some other guy said (and pictured) that weren't on his 799s are present on this head... Its also smooth like the multiple 243s I own. Is the chamber identical? I don't know but will look when I get out in the shop one of these nights.
I am willing and completely regardless of this forum or any other am going to have some of these heads flow tested. I also want to take a set of 862s or 706s and install a 2" intake valve flowing them before and after as with the way the stock 1.89" intake fits there is room for improvement.
If you do the testing it would be really awesome to see back to back testing on the same bench between them all, especially with the before and after 2" valves on the 706 heads vs the others. And the 243's vs 799 with the top cut. The other guy tested 243's with a top cut the 799 didn't have...
Now I'm wondering if not all 799's are created equal if yours have the top cut and his didn't.
I'd really like to know if a 243 with a 61cc chamber is or is not better than a 706. But 243's keep getting tested as 799's and tested against 706's, while being down on compression, and then judged when they are down 5-10 hp in the low end, which should be made up by the compression. And we all know what happens on the big end between these two heads.
Last edited by 00pooterSS; 02-13-2020 at 04:32 PM.
post like this hurt my brain to technical for me at times lol
seriously tho how much HP/TQ do you think the difference can be between the 3 heads? or is it more about this head with smaller cams and this one with bigger type of deal?
That's awesome fastbrick, I appreciate the post. Even if it is 243 vs 241
Looks like the 241 has a flatter floor that flows into a sharp turn on the short side, and the 243 port floor dips down closer to the intake side then comes back up then has a smoother transition down around the short side to the back of the valve. Interesting.
Really cool cutaways there, thanks again.
It's all I could find and from back in the day.
The old Sponsor's who ported heads used to cut them open and check them for how much meat was in them for porting purposes.
Occasionally they would post stuff like that up.
You don't see that kind of stuff today. Everyone is a professional porter even at home so much less participation.
post like this hurt my brain to technical for me at times lol
seriously tho how much HP/TQ do you think the difference can be between the 3 heads? or is it more about this head with smaller cams and this one with bigger type of deal?
It's just me being super curious about things that most would consider a waste of time. There wont be any big numbers. It's just something I've been really curious about. And it would be nice to know what the baddest out of the box cathedral head is for budget builds. We already know it's these 3 for motors that want decent compression. But, I'm still curious of the differences in the 3.
Over here the crowd favorite is the 706. On LS1tech it's the 243.
Part of what got me going on this was seeing a guy make 470 to the tire with a stock long block that had a stock cam and stock 243 heads. It does have a fast intake and lots of little things done to free up power. But it is still shocking.
Then I saw these test come out where 706 heads make more than the 243 but they also tested the 243 at lower compression then judged it for being down a little bit of power in the lower rpm range. So I just wanted to open discussion and look at pictures.
Add to all that I've always thought the 799 should do as well as the 243 based on what everyone said. Then I saw the thread I posted where the dude posted up flow differences between the 799 and 243 and it all got me thinking that I want to see more detailed info on these heads and the 706 in comparison.
Ultimately, none of these will make or break someones combo. But some of us feel one head is a clear winner over the other but I haven't seen a fair test between them, only biased tests.
Is it mostly a waste of time? Pretty much lol.
I think what we will find is that in stock form the go to head for guys should be the 706 if you have a 4.8 or 5.3. The smaller valves well help reduce shrouding losses on the small bore. I think the 243/799 would be good for the 3.898+ bores, maybe.. For sure better on 4"
But will the 706 compete or kill the 243 with 2" valves on a 3.9 or 4" bore??? It's a possibility.
One thing I am curious about though is how shrouding will affect power on the ls1 bore of 3.898, most likely the 243 head will be best, but a good 706 with smaller valves and a killer valve job on an other wise stock head may actually kill a 243.
Part of what got me going on this was seeing a guy make 470 to the tire with a stock long block that had a stock cam and stock 243 heads.
whhatttt????
now how to do make that much power on stock heads and cam? my zo6 was full bolt'on, prc 2.5 243's, btr stg 2 ls1/ls2 cam, ported fast92 & ported TB put down 475/415 wheel, my full bolt ls6 intake manifold z28 also a manual car put down 380rwhp (dont remember tq #'s) how did this guy find h/c/i power on a stock engine? super hard to believe with out seeing it
my brain tells me he had a bottle connected to a button.... but i've been wrong before
02-12-2020, 03:48 PM
lol