"Cliff
If your example did not have rules to follow for his class that 750 Quadrajet on a dual plane aftermarket intake manifold would have been too small on cfm by a couple hundred . This is where the aftermarket manifolds shine / The cork in the system becomes
the carburetor, especially on a true dual plane intake."
Some race Classes require the factory intake to be used. Nothing more, nothing less. My example simply shows that a flat iron big block Chevy intake is fully capable of making big power. It's not meant to compare it to anything else.
You also know nothing about the carburetor used, it was done here and specifically built for FAST Class racing. To maintain the privacy for my customers I will not reveal any details on those particular units. I have other Q-jets out there in FAST Class applications, several run into the high 9's and those cars do it on 8" bias ply tires, so the level of performance we are getting is most likely WAY above the vehicles owned by most who are reading this..
I'd also add here that on more than one occasion I've back to back tested intake manifolds with no other changes. I've also tested them in conjunction with 4 different 1" spacers.
On one outing (private track rental) I tested my "modified" cast iron Pontiac intake against the new (at that time) Tomahawk intake. I also added a 1" spacer to the Tomahawk as well for comparisons. The Tomahawk intake is basically a well modified Holley Street Dominator single plane intake professionally ported by Dave at SD Performance then used to supply the scan for the final product originally marketed/sold by Ace at Pacific Performance Racing.
Without a spacer it ran SLOWER everyplace, 60', 1/8th and 1/4 mile, worse in ET and less MPH.
With a 1" spacer and eventually swapping over to my very well prepared 4781-2 850 Holley DP carb it ran almost 2mph faster, but slightly slower in ET by .02 seconds to my factory cast iron intake with no spacer at all. I repeated the test and same thing buy .03" seconds slower but still almost 2 MPH faster.
Where it really gave up power was 60' and short times. Even with a stronger top end charge (it obviously made more upper mid-range and top end power) it was not enough to offset the loss of low RPM and average power.
So it was NOT hitting the converter as hard, the tires as hard, or pulling as hard off the line thru the 60', but pulling harder at the top end of the track.
I know testing like this is difficult for some folks to understand or accept. Edelbrock (and many other companies selling "high performance" parts) have to tell us how much better they or they'd have trouble selling them in the first place. So if you don't test anything you'll simply be like everyone out their and think that all of these products are superior to factory parts at every level.......FWIW
