speedtigger

iTrader: (16)

Sounds like he is falling down on the job LOL. He is very technical. I will tell him he needs to slow his roll and speak english and keep it simple. Hold tight until tomorrow at least.

savage9scorpio

Okay. A little off topic and random but here's my current ride/toy Black Panther is her name :

89gmcs15

iTrader: (7)

Psh, not a car for miles here in nd and the roads are perfectly straight. It's all good.

newschool72

iTrader: (12)

I think the PTV clearance Martin is speaking of is with short runners on the intake the intake center line, lift ,and duration would have to be such to require fly cuts to get all you can from the combo.
As for the dual vrs single plane intakes, the GMPP dual plane is the only one out there for the LS3 heads and good info is hard to find. I have that intake on my engine and have had a hard time finding info on testing. The only tests I have seen was D&A machines dyno challenge setup. They tested the dual vrs the single on two different displacements (337cid and 409cid). On all the combos they tested the GMPP dual plane made more HP and TQ at all rpms ! I think the confusion on dual vrs single LS3 intakes is that everyone is referencing the SBC or cathedral port setups to make a judgment on the big heads. The truth of the matter, IMO, is the LS3 dual plane will move massive amounts of air and I think it would take a really big LS engine to need more than the dual plane could move. More than the 409cid that Andy tested for sure. If you haven't looked at the GMPP dual in person, its hard to understand just how big those runners are. That being said, I think the dual will move better air than the single on anything short of 427cid and 7K+rpms. The fact that there are so few of the GMPP dual intakes out there to test makes it hard for a cam grinder like Martin to spec a cam that is perfect for the combo. I can tell you that Andy found the intake LOVES short durations and really tight LSAs. With a 226 at .050 and a 106 LSA cam the 409 made 545 ftlbs at 2500RPMs!! how is that for a sluggish LS3 port ! It made max torque at 3500RPMs (595ft lb). It made just under 600HP up top at less than 6K. That is a low 11, high 10 sec engine that only needs a 2500rpm stall and mild gears to get there. Pretty impressive combo for the mild nature of the beast, IMO.

Doug G

23X/24X @ .050, 110 LSA and LS3 heads shaved .050 required my LQ4 pistons (stock dished) to be fly-cut .100

I don't see that cam fitting without fly-cutting on a 6.0L, even on unshaved LS3 heads due t the valve size.(but they have A LOT more experience than me)

Without the right stall and gears you will be down on HP/TQ with that combo.

speedtigger

iTrader: (16)

I would love to see some of his test data and dyno sheets. Wouldn't it be something, if the dual plane, square port combo was the ultimate street combo and it was never realized by the LS community?

I can tell you from my experience with the Performer RPM for cathedral ports that the intake ports are very small inside and is very restrictive. And, while the intake does offer substantial torque gains down low, it becomes a substantial restriction above 5000 RPM even on stock displacement engines. After inspecting and measuring the intake, it made me wonder why Edelbrock gave it the RPM moniker. It should be a regular Performer.

newschool72

iTrader: (12)

Andy posted up a couple dyno sheets on this forum last year, but they were from early in the testing. The dual made about 10-15 more HP than the vic jr all the way through, but I think the sheets were from the 337cid and it was from a cam profile that came before they FOUND the tight LSA was the way to go. He said the later dyno #s were much better with the dual than the single, but never posted them. I know the 409 w the short tight cam was the one they used in the dyno challenge and posted the great #s down low. I have no complains with the intake I have and it makes great power from idle to the red line. I have some work to do to find my issues with a low peak rpm in my setup, but I will get it figured out eventually. May be fuel or a very restrictive exhaust, but I peak out at 6K. Ive gone to a much less restrictive muffler so far but haven't been back to the track for testing. I will be watching the A/F at the same time. All I can say at this point is the LS3 heads are not living up to their rep as sluggish down low with my dual plane and short ,tight cam.

savage9scorpio

With all that you just stated I see that if I'm gonna be happy with the power the engine is capable of making, I'm gonna have to man up and just flycut the pistons. But having the mindset that I do there's no way I'm gonna b happy flycutting stock pistons.
I'm guess im gonna listen to these 408 demons whispering to me and go ahead and build something ill be happy with for seasons to come.(since I'm n no rush to get the motor running this race season.)

Whoever this Andy is has opened my eyes up go a whole different way to take the motor and I'd like to duplicate #'s very similar to what you posted.
I've learned from the old head posts that "if your gonna do it right do it right the 1st time"
Thanks for you all's posts. Becoming a member of this site has really opened my mind up to these ls motors. . =)

speedtigger

iTrader: (16)

I was exactly where you are at 3 years ago. What I saw LS engine do, made me never want to build another Buick 455. Then once I built my car, I was even surprised more by just how fast it was for what I spent.

speedtigger

iTrader: (16)

That car is very sneaky, but the idle gives you away.

TXsilverado

iTrader: (18)

coming from someone who went the 408 route...dont do it IMO. punch your motor .030 and throw a good piston in and be done with it. a 408 is an expensive headache. if you're willing to spend the money on a 408, take that money and put it to a good cathedral aftermarket casting and some forged slugs.

dogsballs

these piston are 300+ thick, stop being a girl, fly-cut IF required.

saying that i don't think you'll need to if you go a smallish 220's deal.

heck my 236/246, 613/613 on 110, with 100thou off ls3 heads only needed 60/70 thou fly-cuts. still heaps of meat left, i'd even gas it 150-200hp.

speedtigger

iTrader: (16)

Wow, really?

savage9scorpio

So your suggesting

Doug G

Better at lower rpm w/ a dual plane....but 4000+ stall,4.xx gears, you'll want a single.

Doug G

With the LS3 valve size and the 6.0L bore size....the fly-cut is over the ring.

Sales@Tick

iTrader: (3)

For years on this board and others, the myth that a single plane short runner intake manifold makes less torque than a dual plane or Fast intake has been told. That the torque lost from a longer runner cannot in any way shape or form be made up when switched to a short runner single plane intake.

This is false.

This is said because cam timing events are not proper for the combination. There is a thread in the Gen 3 section right now where I just did a cam for a gentleman. He switched from a Fast 102 on his TFS 225 combo and EPS cam to a Super Victor and one of my custom cams. My custom cam is larger than his old EPS cam, and we were still able to match the torque curve pound ft. tq. for lb. ft. of torque up to 5000rpm where the single plane started to pull away. Uncorrected the gains were 32-33rwhp. SAE corrected for weather conditions on both days they were much, much more.

Some will say, but it's a big lazy port with no velocity. Au contraire mon frere'. The main reason the LS3 heads don't perform on par in regards to torque values down low is once again cam timing. The port is very large, it has a large intake valve. We do not need to hold the intake valve open nearly as long to fill the cylinder at higher rpm's fully. This improves low speed torque greatly. As valve lift is increased, air speed in the runner increases as well. ICL is a measure of how many crank degrees it takes the intake lobe to reach peak valve lift after TDC. If we can reach that peak valve lift sooner after TDC, we're reaching peak air speed in the intake port sooner. This will help build port speed at lower piston speeds(engine rpm) and close the intake valve earlier from the further advanced ICL.

With a single plane, we need the signal from overlap to help accelerate the intake charge into the port until the downward motion of the piston and the negative pressure left behind the piston can help aid in pulling that charge into the cylinder.

Only problem with overlap is it can create P to V issues when the piston nears or is at TDC. This problem is exasperated by the large LS3 intake valve.

This is why I recommended fly-cutting for the OP so he could have the most powerful set-up possible. With great bottom end and top end.

I can grind a cam that will not require fly-cutting, but I've found that these LS3 combo's really like compression as well. While you're fly-cutting, you may as well fly-cut enough to mill the heads some too. Milling is cheap and easy to find a machine shop to do it.

Hope this helps.

dogsballs

not really. excuse the chatter marks.




yes, there probably is a bit of swarf in the run-out.

TXsilverado

iTrader: (18)

so what are yalls thoughts on spraying with flycut pistons?

speedtigger

iTrader: (16)

That exhaust valve relief is definitely directly on top of the ring area.