Intake Manifold Porting Show ‘n Tell

[skinny z]

I was going to post this too!
Presently shopping for a Dominator!

[mt-engines]

Yea.. no words needed.

That was a complete mess. With what little you had to work with, you did what you could within the limits of the manifold. Hats off to you. Do you think it'll make the gain that he was looking for, to over 800 horsepower with AFR 245s?

Unless there is some moderate port work done to the AFR245s you won't get 800hp unless its on a happy dyno.. maybe if a tunnel ram is used.

[ChopperScott]

AFR 4811 v3.00, to be paired with AFR 245s. Work in progress…

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[ChopperScott]

Yea.. no words needed.

That was a complete mess. With what little you had to work with, you did what you could within the limits of the manifold. Hats off to you. Do you think it'll make the gain that he was looking for, to over 800 horsepower with AFR 245s?

Unless there is some moderate port work done to the AFR245s you won't get 800hp unless its on a happy dyno.. maybe if a tunnel ram is used.

… or twin turbos.

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[Bob Hollinshead]

Watch then discuss.
(F-bird, I expect no less than 6 post in a row from you ).

Big numbers from a stock unported airgap intake... if the 4150 supported all the airflow the engine needed with that intake then it must have been a jigher quality of atomization from the 4500 to make the difference in power? or is there something else going on there with the angle of the spacer/adapter?

[Tom68]

Watch then discuss.
(F-bird, I expect no less than 6 post in a row from you ).

Big numbers from a stock unported airgap intake... if the 4150 supported all the airflow the engine needed with that intake then it must have been a jigher quality of atomization from the 4500 to make the difference in power? or is there something else going on there with the angle of the spacer/adapter?

Bigger carb, 50CFM on paper, could be more than that if it was flow tested, as someone mentioned in the comments, pity he didn't monitor manifold Vac.

[HQM383]

Watch then discuss.
(F-bird, I expect no less than 6 post in a row from you ).

Big numbers from a stock unported airgap intake... if the 4150 supported all the airflow the engine needed with that intake then it must have been a jigher quality of atomization from the 4500 to make the difference in power? or is there something else going on there with the angle of the spacer/adapter?

Maybe several contributors.

Raised height from plenum shallow side?

Dominator throttle bores are spaced further apart creating less turbulence between throttle bores?

The spacer reduces in area from carb to plenum. Does this have the effect of raising plenum pressure?

Does the reduction in area increase velocity keeping the fuel atomized?

A further question. How would this set up perform if there was a larger csa dual plane?

[Tom68]

Dominator throttle bores are spaced further apart creating less turbulence between throttle bores?

Raised height from plenum shallow side.

A further question. How would this set up perform if there was a larger csa dual plane?

Dominator throttle bores bigger, lower airspeed turn into fall out vulnerable high side plenum.

Yer, it might have wanted to keep going, also would have been interesting on a 350.

[HQM383]

Dominator throttle bores are spaced further apart creating less turbulence between throttle bores?

Raised height from plenum shallow side.

A further question. How would this set up perform if there was a larger csa dual plane?

Dominator throttle bores bigger, lower airspeed turn into fall out vulnerable high side plenum.

Yer, it might have wanted to keep going, also would have been interesting on a 350.

That too! There is also what is happening back the other way. Does the spacer dampen pesky reversion even better as it travels back to the carb due to increasing area?

[Tom68]

Dominator throttle bores are spaced further apart creating less turbulence between throttle bores?

Raised height from plenum shallow side.

A further question. How would this set up perform if there was a larger csa dual plane?

Dominator throttle bores bigger, lower airspeed turn into fall out vulnerable high side plenum.

Yer, it might have wanted to keep going, also would have been interesting on a 350.

That too! There is also what is happening back the other way. Does the spacer dampen pesky reversion even better as it travels back to the carb due to increasing area?

WOT reversion is somewhat taken care of with a dual plane with cylinder robbing across the plenum, can be a problem at lower revs where the opening valve doesn't have enough air speed and they possibly backflow through the carb picking up more fuel.

I personally don't believe spacers of any sort do a lot with reversion, I have no proof of that though, smaller carb might resist reversion with higher airspeed, but that's not an acceptable fix.

[ChopperScott]

AFR 4811 v3.00, to be paired with AFR 245s. Work in progress…

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[1980RS]

Scott's work makes mine look like amature hour

[cab0154]

from a $60k winning scca 308" sbf trans am engine build from the late 90s.

[hoffman900]

from a $60k winning scca 308" sbf trans am engine build from the late 90s.

Figure near 2 lateral g’s, even in the late 90s, with spikes over that from hitting curbs. Part throttle to feeding in throttle at that time as well.

Also, most US road courses are clockwise, so usually more right hand corners.

I can’t really see how manifold porting is useful without O2s in primaries and being on track, where gforces make a big difference. Engines live in vehicles on race tracks (or on water), not dynos, and definitely not flowbenches. This is a good example of that.

[cab0154]

those cars were 80" wide with 28" of rubber on the rear....lol. there was some lateral Gs. We are putting together our own fox body tube chassis trans am car to go vintage race. most of those guys with their sn bodied cars are running 400" windsors. we are gonna run the c3 headed 308.