hypothetically??
On The Tree
Joined: Mar 2015
Posts: 154
Likes: 12
I posted the graph from that in Gen IV yesterday. Two issues with that test: 1) the 4.030" bore doesn't help the LS3 head and it's huge valve. 2) the FAST intake manifold is garbage.
It homogenizes the performance so bad that it essentially creates the same result.
The real test would be to put a Super Victor on both with a single plane cam. I bet there's a 30+HP difference and no visible change in torque between the heads. Torque would be down vs the FAST, but power would be up significantly for both heads. Add a solid roller to the mix and you have even more of a runaway for the rectangle ports as the RPMs keep climbing.
Now, does that equate to best "street" head? Not really. But it does show a clear advantage on that type of motor. And that's where the rectangle port head is worth it.
I will say this - 1.55 to 1.60HP per CID is a rule of thumb that Tooley threw at me the other day for plastic stock style intakes and hydraulic cams. I went back and looked at just about magazine article and engine dyno I could find. It holds up well regardless of the combination. It's just physics.
But move to a single plane and solid roller and it moves up pretty significantly. To something more like 1.75HP per CID.
I think what we need are better intakes that don't choke out the heads. No aftermarket intake that isn't a Beck, Victor, or MAST intake even comes close to matching these insane flow rates of these new heads. It's where the next revolution needs to come. Then, you'd see more out of any of the heads you're looking at. Otherwise, stick with 243s and port them. TEA 243s hit 625HP with the same cam and 408 setup for Hot Rod as the MAST heads did when they hit 630. So did TFS 235s, PRC 237s, AFR 247s... etc etc. The FAST just kills the heads. Everything was within 10HP of everything else.
It homogenizes the performance so bad that it essentially creates the same result.
The real test would be to put a Super Victor on both with a single plane cam. I bet there's a 30+HP difference and no visible change in torque between the heads. Torque would be down vs the FAST, but power would be up significantly for both heads. Add a solid roller to the mix and you have even more of a runaway for the rectangle ports as the RPMs keep climbing.
Now, does that equate to best "street" head? Not really. But it does show a clear advantage on that type of motor. And that's where the rectangle port head is worth it.
I will say this - 1.55 to 1.60HP per CID is a rule of thumb that Tooley threw at me the other day for plastic stock style intakes and hydraulic cams. I went back and looked at just about magazine article and engine dyno I could find. It holds up well regardless of the combination. It's just physics.
But move to a single plane and solid roller and it moves up pretty significantly. To something more like 1.75HP per CID.
I think what we need are better intakes that don't choke out the heads. No aftermarket intake that isn't a Beck, Victor, or MAST intake even comes close to matching these insane flow rates of these new heads. It's where the next revolution needs to come. Then, you'd see more out of any of the heads you're looking at. Otherwise, stick with 243s and port them. TEA 243s hit 625HP with the same cam and 408 setup for Hot Rod as the MAST heads did when they hit 630. So did TFS 235s, PRC 237s, AFR 247s... etc etc. The FAST just kills the heads. Everything was within 10HP of everything else.
I posted the graph from that in Gen IV yesterday. Two issues with that test: 1) the 4.030" bore doesn't help the LS3 head and it's huge valve. 2) the FAST intake manifold is garbage.
It homogenizes the performance so bad that it essentially creates the same result.
The real test would be to put a Super Victor on both with a single plane cam. I bet there's a 30+HP difference and no visible change in torque between the heads. Torque would be down vs the FAST, but power would be up significantly for both heads. Add a solid roller to the mix and you have even more of a runaway for the rectangle ports as the RPMs keep climbing.
Now, does that equate to best "street" head? Not really. But it does show a clear advantage on that type of motor. And that's where the rectangle port head is worth it.
I will say this - 1.55 to 1.60HP per CID is a rule of thumb that Tooley threw at me the other day for plastic stock style intakes and hydraulic cams. I went back and looked at just about magazine article and engine dyno I could find. It holds up well regardless of the combination. It's just physics.
But move to a single plane and solid roller and it moves up pretty significantly. To something more like 1.75HP per CID.
I think what we need are better intakes that don't choke out the heads. No aftermarket intake that isn't a Beck, Victor, or MAST intake even comes close to matching these insane flow rates of these new heads. It's where the next revolution needs to come. Then, you'd see more out of any of the heads you're looking at. Otherwise, stick with 243s and port them. TEA 243s hit 625HP with the same cam and 408 setup for Hot Rod as the MAST heads did when they hit 630. So did TFS 235s, PRC 237s, AFR 247s... etc etc. The FAST just kills the heads. Everything was within 10HP of everything else.
It homogenizes the performance so bad that it essentially creates the same result.
The real test would be to put a Super Victor on both with a single plane cam. I bet there's a 30+HP difference and no visible change in torque between the heads. Torque would be down vs the FAST, but power would be up significantly for both heads. Add a solid roller to the mix and you have even more of a runaway for the rectangle ports as the RPMs keep climbing.
Now, does that equate to best "street" head? Not really. But it does show a clear advantage on that type of motor. And that's where the rectangle port head is worth it.
I will say this - 1.55 to 1.60HP per CID is a rule of thumb that Tooley threw at me the other day for plastic stock style intakes and hydraulic cams. I went back and looked at just about magazine article and engine dyno I could find. It holds up well regardless of the combination. It's just physics.
But move to a single plane and solid roller and it moves up pretty significantly. To something more like 1.75HP per CID.
I think what we need are better intakes that don't choke out the heads. No aftermarket intake that isn't a Beck, Victor, or MAST intake even comes close to matching these insane flow rates of these new heads. It's where the next revolution needs to come. Then, you'd see more out of any of the heads you're looking at. Otherwise, stick with 243s and port them. TEA 243s hit 625HP with the same cam and 408 setup for Hot Rod as the MAST heads did when they hit 630. So did TFS 235s, PRC 237s, AFR 247s... etc etc. The FAST just kills the heads. Everything was within 10HP of everything else.
So usually it it is the cam blamed for every inconvenient result, now it is the intake.
I believe the intake is imperfect BUT most of us are going to stick with a stockish intake.
TECH Veteran
Joined: Sep 2014
Posts: 4,891
Likes: 703
From: Mississippi
The Fast style intake is why I personally think there are so many LS7 headed combos under 600 horse at tire. I could be wrong but that's my opinion .
The LS7 head are superior to a LS3 head. Factory cnc head at 12 degrees valve angle makes it a nice option. Only drawback I hear too many guys dropping a valve with the LS7 head. Anyway let's keep this thread going. It's getting better and better.
The LS7 head are superior to a LS3 head. Factory cnc head at 12 degrees valve angle makes it a nice option. Only drawback I hear too many guys dropping a valve with the LS7 head. Anyway let's keep this thread going. It's getting better and better.
Jake brought up an interesting figure HP per cube.
LS6 1.184 using 410 and 346ci
LS3 1.159 using 436 and 376ci
If the LS3 made the same HP per cube as the LS6 it would be 445hp and not needed the deeper first gear in the auto or deeper axle gear paired with the M6.
And hell what would an LS6 with TBSS intake do, testing indicates compared to the LS6 intake a small peak HP bump with a fairly significant gain in the midrange.
Seems to me GM could have easily achieved/exceeded the same HP goals with more area under the curve with a redesigned cathederal head using say a 2.08 valve that would have reused existing intake manifolds.
So why doesn't a believer tell me why they went to huge ports and valves to make less HP per cube with essentially the same cam?
LS6 1.184 using 410 and 346ci
LS3 1.159 using 436 and 376ci
If the LS3 made the same HP per cube as the LS6 it would be 445hp and not needed the deeper first gear in the auto or deeper axle gear paired with the M6.
And hell what would an LS6 with TBSS intake do, testing indicates compared to the LS6 intake a small peak HP bump with a fairly significant gain in the midrange.
Seems to me GM could have easily achieved/exceeded the same HP goals with more area under the curve with a redesigned cathederal head using say a 2.08 valve that would have reused existing intake manifolds.
So why doesn't a believer tell me why they went to huge ports and valves to make less HP per cube with essentially the same cam?
Last edited by 96capricemgr; Nov 27, 2015 at 03:07 PM.
Yes, I know this is an old thread. It's a great read, but I wanted to share a couple of points I had not seen made.
Keep in mind that consumers are more aware than ever of Noise, Vibration, and Harshness (NVH) in today's market, and that engineers are also forced to adhere to tightening emissions and economy restrictions. All the comparisons made are accurate and valid if performance increases are the only goal.
http://www.superchevy.com/how-to/vem...te-ls3-engine/
One last note, it has been mentioned that these heads lend themselves to positive displacement blowers. As the debate is over technology brought to market in 2008, it is interesting to note that is exactly what happened in later years with the LS9/LSA engines.
Now I will don the flame suit for those who wish to point out that this thread had been dormant for three months....
Keep in mind that consumers are more aware than ever of Noise, Vibration, and Harshness (NVH) in today's market, and that engineers are also forced to adhere to tightening emissions and economy restrictions. All the comparisons made are accurate and valid if performance increases are the only goal.
http://www.superchevy.com/how-to/vem...te-ls3-engine/
What we put together is a good balance. It gives you emissions capability, fuel efficiency, and much more performance [than the LS2]. It's a quieter application, too. We've added some features for refinement, but someone who wants to actually go out and increase the performance of the LS3 has a lot of capability to do that.
Now I will don the flame suit for those who wish to point out that this thread had been dormant for three months....
