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I say, let the discussion continue!
The OP hasn’t posted since post #53, where it sounded like he got all his questions answered.
This has been an interesting discussion on many things related to intakes in general, which have been somewhat educational for the readers.
There has been no negative posts and many members may learn something from this discussion.
I personally ran dual quads on a Buick Skylark GS 455 and it ran so much better than with a single quad.
I also ran dual quad tunnel rams on all my drag and ski boats for decades with great results.
Yes it has gone off what the OP asked for, but maybe he is learning something as well.
One intake people talk about, but not much info on. Is a holley street dominator I do have one.
has 2.015 x 1.250 exit area from holley.
I think you can compare some duel planes by simply looking at there exit area. Probably is the min cross section of the runner.
the holley stock, not touched. should flow decent.
And it did, 244cfm on number 6.
6. Same runner as tests above and it didn't line up perfectly with the head. Bolt holes on intake had 0 give to move it around some.
Edlebrock , weiand, holley all list there exit sizes. So maybe it will give you a idea what you want.
I really don't understand the big plenum etc has less low end theory. If you want good combustion at low rpm, say 1000 to 3000 rpm.
than run a 100% divided duel plane
Most of you have seen the dyno charts how the duel plane is better at 3000 than single plane .
What your seeing is better combustion efficiency. if you want better combustion at 1000rpm you should run a completely divided duel plane. Including a divided carb gasket. No reversion, no exhaust gases getting into the mix, will have alot better combustion at these rpms. Sure there is a bag of tricks to help this. But the best solution is 100% divided. You will feel a difference
Don't think big is bad. Bigger runners, plenum is needed for flow.
Stock Ls flows way more with intake bolted on head, than almost all steet sbc do.
The short height plenum on a duel plane flows less, a 1inch spacer will help this . Maybe big runners, a spacer and 100% divided is best. Idk. But
you have to have some flow.
Holley on flow bench
Holley/ weiand stealth.
Big plenum and runners are great for Fuel Injection but won’t pull a good signal to draw fuel from the carburetor or keep the mixture atomized and single plane manifold makes matters even worse .
The intake should always flow more cfm than cylinder heads wether it’s dual or single plane as far as the flow
[QUOTE=Eric P;1606120644]Big plenum and runners are great for Fuel Injection but won’t pull a good signal to draw fuel from the carburetor or keep the mixture atomized and single plane manifold makes matters even worse .
I think that statement is a little misleading. Makes it sound like injection changes the dynamics.
you still have the same crap quality of air from reversion/exhaust. LS just has way longer runners . Just like a 100% divided duel plane on a
Ls makes way more down low with a carb than the longer injection oem intake. Ls3 dual plane is a good example.
I ran the holley above on a car and a cheap Chinese duel plane with the divider cut down. The holley destroyed it down low rpm. And the holley flows ok.
Big plenum and runners are great for Fuel Injection but won’t pull a good signal to draw fuel from the carburetor or keep the mixture atomized and single plane manifold makes matters even worse .
I think that statement is a little misleading. Makes it sound like injection changes the dynamics.
you still have the same crap quality of air from reversion/exhaust. LS just has way longer runners . Just like a 100% divided duel plane on a
Ls makes way more down low with a carb than the longer injection oem intake. Ls3 dual plane is a good example.
I ran the holley above on a car and a cheap Chinese duel plane with the divider cut down. The holley destroyed it down low rpm. And the holley flows ok.
According to the dyno tests Ive seen and read about that is the only real functional difference between the rpm and the air gap though, the center cutout which allows those extra 5-7hp at top rpms at the cost of the better signal strength / velocity at lower rpms. The cutout is a bit of a compromise to allow a DUAL plane to have a bit of the advantage the single plane has at WOT
I recommend the 2101 at this power level......it flows plenty and will beat the stock Q-Jet manifold all around....it is perfect for a Q-Jet....just make sure you use an open thermo 1/4" spacer/gasket (various outfits have these but you can get them from Cliff's site).....they work best with this spacer/gasket.....the 2101 will work with the choke and is a bolt on.
The 7104 RPM Q-Jet is great too if you have the clearance.....I do not believe it is any taller than the factory LT-1 Winters intake, so it should work under your big block/LT-1 hood.
2701 EPS is a great intake but square bore only......
The other option is the ZZ4 intake.....which is basically a 2101 with a Chevy emblem cast into it......
The other thing I do is run 1204 Fel pro intake gaskets to block the heat riser......the miserable heat riser plumbs hot exhaust to the base of the carb....exactly what you do not want....the choke will take longer to pull off, but depending on where you are, the choke is not needed in some cases.....
The last thing I want to point out is I always use 12pt ARP stainless intake bolts.....cheap or black oxide bolts look like **** in 2 years, and the 12 pt makes it easy to get a wrench in the four center bolts.......also, make sure you use a little PTFE sealant on the bolts.....even the blind ones.....oil and coolant like to seep through those threads.....
