General Category > Quadrajet Carb Talk and Tips
Intake manifolds
old cars:
Read This
http://www.sdperformance.com/newsStory.php?newsID=44
Cliff Ruggles:
Is there a point to be made here?
Googling up the efforts of others is at least 2nd or 3rd hand information. Makes for nice reading but 474cid and over 525hp and up near 600 ft lbs torque is getting into the arena where we need to move a LOT of air to keep up.
I'll add here that a third party (I supplied the Q-jet for it) duplicated that engine build and used a "modified" Pontiac 455 HO intake. It was not on the same dyno and the engine had a little more compression, but the same 290cfm heads and 236/245/112 "Old Faithful" camshaft.
That engine made 554hp/604tq, or more power than all the intakes Dave tested on his nearly identical engine build.
I've dyno'd all the 455's built here and when we want bragging rights number we finish the testing with a Torker II topped with a 1" spacer and at least an 850cfm carburetor. They will always make more power from 4500rpm on up to peak HP.
That set-up more times than not doesn't run as quick in the same vehicle at the track (gives up to much on the starting line, 60') but will typically run 1-2 mph faster on top end.........FWIW.......Cliff
Mudsport96:
Some time ago i found numbers on a ported and unported chevy iron manifold. And numbers on ported/unported performer rpm. And the ported iron manifold was just as good as the rpm. Albeit heavier, so maybe get a factory aluminum one from the 80s. But for a chevy making under 500 i wouldnt go to an aftermarket part.
https://cliffshighperformance.com/simplemachinesforum/index.php/topic,3260.msg14163.html#msg14163
Cliff Ruggles:
Way back when I tested my Pontiac iron intake against the RPM the folks at the dyno facility were shocked when the RPM made less power. An RPM intake on at least 90 percent of the SBC builds I see wouldn't bring anything to the table in terms of improved vehicle performance. Very few are at or much over 1hp/CID. The place to spend money on SBC build are the heads. So many excellent offerings out there these days that it surprises me folks still spend time/funds on "smog" era factory iron heads that don't flow for chit after you put tons of work and money into them. They also don't take advantage of the excellent combustion chamber offerings.
A high percentage get "vortec" heads, simply because they are dirt cheap. Then they have to buy an aftermarket intake, and they really need set-up for screw in studs. No provision for an exhaust crossover either, so a horrible choice for your 4 x 4 truck engine that will need to plow snow next Winter.........FWIW........
old cars:
--- Quote from: Mudsport96 on April 23, 2022, 04:31:24 AM ---Some time ago i found numbers on a ported and unported chevy iron manifold. And numbers on ported/unported performer rpm. And the ported iron manifold was just as good as the rpm. Albeit heavier, so maybe get a factory aluminum one from the 80s. But for a chevy making under 500 i wouldnt go to an aftermarket part.
https://cliffshighperformance.com/simplemachinesforum/index.php/topic,3260.msg14163.html#msg14163
--- End quote ---
You Failed to mention the factory SBC intake manifold ported are numbers after 30 hours of porting by a competent person ( David Vizard ) who has much more experience with building SB and BB chevys than the people on this forum.
This type of porting would cost well above and beyond the price of a good aftermarket intake manifold that would equal the results.
Those results as reported by David Vizard also resulted in a 26 HP gain on a motor starting with some 300 hp.
That doesn't say much for those old SBC intake manifolds.
Navigation
[0] Message Index
[#] Next page
Go to full version