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Plenum Volume vs runner length vs RPM /torque ranch

Darkman270 (Automotive) (OP)
20 Dec 01 15:24
Is there a formula to determine the volume of a intake plenum vs the runner length? I am fabricating a intake for a inline 6 cylinder. This requires some lengthy runners and a long plenum.

What epoxys could be used on cast aluminum to reshape the inside of the plenum?
MaxRaceSoftware (Automotive)
20 Dec 01 17:02
in the plenum area of the sheetmetal intake i would use
 A B Epoxy
known as AB sticks ...sold by Moroso and many others

or you could go directly to;

Martin R. Carbone, Inc.

the sticks will adhere good as be easier to use
or for a little better epoxy;

greater adhesion but more hassle to use
would be KopCoat from Reher-Morrison

i use KopCoat in ports and seal it with Devcon 2-Ton clear Epoxy

Larry Meaux  (
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

Darkman270 (Automotive) (OP)
20 Dec 01 20:35
Would the KopCoat and Devcon 2-Ton be suitable to raise the floor of an exhaust port as in the 351C 4bbl head? If I did this would I realize any power gains over port plates that have tonques that block the lower portion of the port? These heads will be used on a street car with 4spd and 4.11+ gears. If you need more engine details I could give them.
MaxRaceSoftware (Automotive)
20 Dec 01 21:22
the KopCoat is the old name...(Sorry for the mistake)
the name for the same product is
  ZSpar  A-788 Splash Zone Compound

 Goodson sells this same thing as PRK-99 epoxy port reshaping kit kind of epoxy i've seen yet will work
in an exhaust port :(

at least not very long

EGT temps are usually 1000 to 1500 deg eventually anywhere from  a couple of seconds to a couple of hours ..your epoxy is history  !!!

Larry Meaux  (
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

Darkman270 (Automotive) (OP)
20 Dec 01 22:36
Thanks, Let's move over to the intake port. Ford's have allways been weak on the exhaust so let's just use the port plates on the exhaust. On the intake how about using a two barrel intake and use the epoxy on the intake side of the head to match the intake manifold. I'm sure you realize I'm trying to increase the velocity and decrease the volumn of the 351C 4bbl head's intake runner. I'm trying to increase port flow for low end torque and streetability.
MaxRaceSoftware (Automotive)
20 Dec 01 23:38
Any king of bad intake manifold fitting problem
that will let hot oil get inside the runner
might cause "lifting" of the epoxy..even tough you might have sealed it with Devcon Clear.

Use an old beat up aluma-burr carbide to rough the spots in the ports you want to epoxy

Always mix plenty more epoxy than you will use
to get a good uniform mix..mix it atleast 15 minutes

i really can't recommend you this for the street
without a lot of previous experience 1st with epoxy.

Larry Meaux  (
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

Darkman270 (Automotive) (OP)
21 Dec 01 0:57
I feel comfortable using the epoxy. What are the limits of the build up per application using the product you spoke of. More important do you feel it would be a worthy endeavor on these heads modifying the intake port. I would think it would have to help.
MaxRaceSoftware (Automotive)
21 Dec 01 21:31
Did you ever think about just doing the 2-351C heads ??

i've installed the 351C-4 valves into the 351C-2 heads
....and after, the 2-barrell heads flow better on the exhaust side with a slightly better shaped exhaust port in the 2-barrell -VS- the 351C-4

the 2-barrell exhaust port has a better short turn radius after you go to the larger exhaust valve..and the port is overall smaller

the intake side doesn't flow as good as the 351C-4..but it has more airspeed and no epoxy ...and at the lower lifts the 2-barrell heads w/the 4-barrell valves will be very close in flow CFM

i've done a few pairs ..these were for street/strip ..and they went faster than the 351C-4 heads on the same cars

Larry Meaux  (
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

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