[john hadcock]

How much power could i expect to gain from having my victor intake fully ported?

[Tom Vaught]

Not much if the heads are stock,

That being said, if the intake is slightly better flowing vs the head port's flow, the engine will have excellent volumetric efficiency for that head flow. Otherwise the intake is a "choke point".

Rule of thumb (that seems to work well on everything but all out bracket engines) is: Flow of one port (say 300 cfm @ 28" h2O) times 2=
600 times 1.1 or the engine should make at least 660 HP with a 300 cfm head.

Tom Vaught

[john hadcock]

Sorry about that but the heads are early E-Heads ported and polished flow little over 300cfm, 455 bored 30 with cat rods and ross pistons. Comp cam hydrolic roller with 570 something lift. head have also been milled 64cc,

[cfmcnc]

The manifold is the extension of the port and both should be developed as one tract with crossections and length sized per application.WE use the equation of 2.4 HP per CFM is the potential ,The goal is to access that potential within the desired power curve.Bill C.

[steve25]

With you current Intake flow level just a blending of the plenum into the runners is all that needs to be done.
You can fine tune the motors power band better by changing the plenum volume thru the use of different height spacers if you have the needed Carb to hood clearance to do so.
It will take some track time to do this if the motor, or car is not on a dyno, but its worth it every time!

Most motors of 455 to 480 cid that make peak HP over 6k rpm like a 1/2" taller plenum under the carb
If you are running a large type Dominator Carb the motor will like a four hole type spacer that flares out more from the throttle bores to the exit of the spacer.

On the other end of things if your running open exhaust and have not placed a 16 to 18" collector extention on the headers then its time to do that also.

[grandville455]

How Much You Think This hurts a 600 hp motor? OUT of the box, SD KRE heads flowing 290 cfm
Would it help to smooth out the center divider's in the ports so its not
such a flat wall the mixture is hitting?

[900HP]

We found our 428 was very sensitive to plenum volume and the stock victor 4150 was right on the edge for us. Even adding a 1/2" spacer resulted in a loss of torque and no upper rpm gains either. We needed more time to experiment with filling the plenum a little and reducing the plenum volume even more. This was at 700hp level

[LiL Jack]

Originally Posted by grandville455

How Much You Think This hurts a 600 hp motor? OUT of the box, SD KRE heads flowing 290 cfm
Would it help to smooth out the center divider's in the ports so its not
such a flat wall the mixture is hitting?

Yea cut that clover leaf out.

Don't make the divider really sharp. Just smooth out the casting .
And don't put a clover leaf on the floor.

[john marcella]

RPM and car setup/ gearing- converter are the biggest question here. That is assuming you're trying to make your car faster rather than make a bigger peak hp number.

[Skip Fix]

Originally Posted by 900HP

We found our 428 was very sensitive to plenum volume and the stock victor 4150 was right on the edge for us. Even adding a 1/2" spacer resulted in a loss of torque and no upper rpm gains either. We needed more time to experiment with filling the plenum a little and reducing the plenum volume even more. This was at 700hp level

Did you guys look at a Tomahawk intake any? It has a smaller plenum but also smaller and shorter runners. I think John Angeles the Pontiac SS racer is running one.

Torker II plenum is actually larger than a Victor when you put the numbers to it.

[grandville455]

Originally Posted by john marcella

RPM and car setup/ gearing- converter are the biggest question here. That is assuming you're trying to make your car faster rather than make a bigger peak hp number.

For Me I am looking to go faster , so if smoothing stuff out helps I am all for it. What does taking the cloverleaf out do? Let the plenum flow easier to the port? I shift at 62-6400 right now, 4.10 gear, go thru at 6300. 9" UCC flashes to 48-5000 about 4600 stall.

[ponjohn]

Wouldn't the first order of business be seeing how the Victor runners aline with the heads?

Then go from there?

Is a Victor really required for a 300 cfm head?

[900HP]

Originally Posted by Skip Fix

Did you guys look at a Tomahawk intake any? It has a smaller plenum but also smaller and shorter runners. I think John Angeles the Pontiac SS racer is running one.

Torker II plenum is actually larger than a Victor when you put the numbers to it.

Runner length is your friend when you are trying to make as much torque as possible at low rpm. The trick is keeping velocity up with the runner length.

O.P. I wouldn't be so quick as to cut the clover leaf out. I would radius the tops of the dividers and do a port-match on the intake and run it as-is. You can experiment with different spacers to see if it wants more/less plenum volume.

[ponjohn]

Originally Posted by 900HP

Runner length is your friend when you are trying to make as much torque as possible at low rpm. The trick is keeping velocity up with the runner length.

O.P. I wouldn't be so quick as to cut the clover leaf out. I would radius the tops of the dividers and do a port-match on the intake and run it as-is. You can experiment with different spacers to see if it wants more/less plenum volume.

Does this mean the length but not the volume leads to low speed power?

[900HP]

Originally Posted by ponjohn

Does this mean the length but not the volume leads to low speed power?

If you are considering 3rd order and 4th order harmonic tuning, yes.

Volume is a byproduct of cross-section and length. If you have the same cross-section one intake to another but one intake has a longer runner, the volume will automatically be more. Look at the torque curve (white) line of our 428. That is a byproduct of good intake and exhaust tuning (along with ignition and fuel tuning)

just under 500 ft/lbs at 3000 rpm, 550 ft/lbs at 3500 rpm, 653 ft/lbs at 5200 and it averages 600 ft/lbs from 3000-7000 rpm.

[Skip Fix]

Torker II has slight longer runners just smaller narrow and tall as well as a larger plenum.


My similar to the OPs 455 pump gas motor is clicking 550ish HP depending on the calculator on wt/mph and just using a Torker II so it can support some decent HP with this type motor.

[ponjohn]

If you decide on 3 or 4 harmonic does this dictate the header calculations should be done using the same harmonic?

[john hadcock]

First off i just wanna let every one know that i had this motor built way before i ever really knew anything about pontiacs. :/ The car is a 69 gto pretty much all origanal except for the fiberglass hood. The car weighs 3900 pounds and right now my best time is 10.87 at 127mph. I also have nitrous, but have not ran it yet. It has a turbo 400 tranny, Tci 3500 stall converter, ford 9 inch with 389 gears. I run a MT drag radial 325/50\15. Motor is a 455 bored 30 with stock crank, cat 6.625 rods, ross flat tops with 2 valve relief, 0 deck with E-Head they flow 295 intake a .800 and 314 exaust, they have also been milled to 64cc. 1.65 harland sharp rockers, Comp cam hydrolic roller, 594 intake 618 exaust 242 duration and 248 duration exaust, 110 lobe seperation. The victor intake has been milled to fit the heads and the runners line up nice right now, it has only been gasket matched. It will turn 7000 rpm instantly. Also has super comp headers 2 inch pri and 3.5 collector with 3 inch exaust all the way out the back.

[Skip Fix]

Sounds like you have it going pretty good for what you got!

[john hadcock]

I run a holley 950hp carp 4150.