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| 2-plane intake manifold https://slantsix.org/forum/viewtopic.php?t=29714 |
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| Author: | MikeY [ Wed Jun 25, 2008 5:55 am ] |
| Post subject: | 2-plane intake manifold |
Has anyone ever tried to take an aluminum four barrel intake and install/weld a divider separating the plenum into two halves, the front half for cylinders 1-3, the rear half for cylinders 4-6? What this would do is make a 2-plane, 180 degree manifold. The firing order of the slant allows this. The carb would have to be mounted with the throttle shafts parallel to the engine. It would seem that this could make the engine possibly more responsive, and make four barrel carburetors more practical for use on sixes, a they would "act" smaller. Your thoughts? |
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| Author: | 66aCUDA [ Wed Jun 25, 2008 7:21 am ] |
| Post subject: | |
I run my Eddy like that, I like the results. Frank |
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| Author: | Doctor Dodge [ Wed Jun 25, 2008 7:25 am ] |
| Post subject: | |
I do that with the Hyper-Pak intake and it really helps the low speed and mid range power. DD |
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| Author: | pinkiedog64 [ Wed Jun 25, 2008 10:26 am ] |
| Post subject: | |
How did you go about installing the divider? Do you have any pictures? |
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| Author: | Doc [ Wed Jun 25, 2008 11:08 am ] |
| Post subject: | |
Adding the divider is easy when you are casting the manifolds, you file a big slot in the sand core, where you want the divider, then cast the manifold.  On manifolds already made, I mill a slot through the floor of the manifold, then fit a divider plate. ( first make a cardboard template, then cut it out of aluminum) Install the divider then weld shut the slot to hold it in place. DD |
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| Author: | 66aCUDA [ Thu Jun 26, 2008 6:34 am ] |
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Or just epoxy it in place with JB Weld.  I contured the epoxy so it was smooth. Frank |
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| Author: | wvenable [ Fri Jul 04, 2008 2:08 pm ] |
| Post subject: | |
Okay, I guess I have always taken this for granted - the divided plenum intakes were better for the street (think performer intake-more low end torque) and the open plenum (think torker intake-more power at higher rpm). Sorry for the v-8 examples! So.... could someone explain the nuts and bolts of this? Okay maybe I'm not as smart as a fifth grader! MikeY how would the carb "act" smaller? My Hurricane 4bbl intake should be coming next week and I believe they had originally had a divided plenum in mind when coming up with the design. Thanks for your help! |
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| Author: | Joshie225 [ Fri Jul 04, 2008 2:50 pm ] |
| Post subject: | |
The divided manifold makes for stronger pulses at the carburetor which helps carburetor function. When all 6 cylinders draw from a common plenum the pulses are significantly damped. Since all 6 cylinders can draw from the entire carburetor with a single plenum the instantaneous peak air speed through each venturi is lowered. Carburetors need the air to flow at a certain speed before fuel flows though the main circuit(s). The pulses are simply faster flowing air. So dividing the manifold and carburetor into halves makes the carburetor act smaller because the peak air flow speed is higher and because of this the maximum flow is reduced. To get the same air flow speed though then venturi(s) when all cylinders draw from one plenum the venturi needs to be smaller. I'm going to put a divider in my Clifford manifold and hope the nitrous plate doesn't allow too much "communication" through the gap. The gap in the divider helps to tune the engine speed at which the manifold and carb work. I completely milled the divider out of a Pontiac 400 2bbl manifold for a bomber roundy-round car as it needed all the flow it could get and still made enough torque to blow off the tires. |
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| Author: | wvenable [ Fri Jul 04, 2008 3:29 pm ] |
| Post subject: | |
Thanks, Josh! |
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| Author: | Joshie225 [ Fri Jul 04, 2008 5:10 pm ] |
| Post subject: | |
You bet! I've got the divider for my Clifford just about done. I couldn't mill a slot in the bottom of my manifold like Doc does as my Clifford is water heated and I didn't want to chop up the water passage. I'll be keeping the divider removable for experimentation. I have a reasonably aggressive cam and I expect the divider will help the low end and mid range. If the top end isn't what I expect I can try a bigger carb or remove/modify the divider or even just put a 1/2" open spacer on top. |
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| Author: | Rug_Trucker [ Fri Jul 04, 2008 7:29 pm ] |
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I wouldn't rally call that a "duall plane" I would call it a divided single plane. The intake on my van is a 360* intake. Hence a single plane. It just happens to have seperate runners for the primaries of the carb, and a larger set of runners for the secondaries! So it is a Dual single plane! 2 seperate plenums! Offy made a Toyota intake or two like that. |
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| Author: | Joshie225 [ Fri Jul 04, 2008 7:58 pm ] |
| Post subject: | |
Quote: I wouldn't rally call that a "duall plane" I would call it a divided single plane.
True, but the function is the same in that the firing order is evenly divided in two. The firing order of a V8 is what creates the need for two sets of runners on two overlapping planes. A dual plane on a V8 with a 180° crank would be a divided single plane.
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| Author: | DusterIdiot [ Fri Jul 04, 2008 11:22 pm ] |
| Post subject: | Darn that Doc!!!! |
He told me to do it!!!! You can see a thread when I was getting a divider setup in my Hpak manifold... it actually works well for both tuning and making sure the car gets it's dose of 'mid-range' torque.... The easy part was using a carbide/tile blade for a table saw, or a large cuttoff wheel... taping off the mounting surfaces and just sliding it in until you get it cut where you need... then if you want a 'good job', then have a buddy with welding experience braze it in for you... then get it shaved for flatness and you are ready to go.... Here Cheers! -D.Idiot |
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| Author: | Rug_Trucker [ Sat Jul 05, 2008 6:23 am ] |
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All this talk is really making me want to put my primaries to the driver side when the Offy goes on. |
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| Author: | 68barracuda [ Sat Jul 05, 2008 7:18 am ] |
| Post subject: | Swinging my Holley around hre in RSA |
Will do just that - but with the lack of LOKAR or Bouchillion bits over here - exchange rate is awful since Bobs COCKUP next door I am fashioning a ball link solution to hook up to the stock levers Same idea they used with the Dual Weber manifolds over here Talking of witch Casting date in October - for all interested parties - will post photos of What the setup will look like and the Manifold has water heated plenum's |
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