Intake manifold mods?

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chopped850
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Intake manifold mods?

#1

Post by chopped850 » Tue Aug 24, 2010 10:59 pm

So has anyone modded the intake to better split the intake charge? Kinda like a shovel intake that has the triangular shape in the back to split the charge as it's forced into the heads? It just seems that the panhead intake tube could be modified at the flat back with some exrta material added kinds the same to split the charge. Just wondering as I didn't find anything in the search box. Also is it possible to adapt a shovel intake manifold and run the carb on the left side of the motor?



Cotten
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Re: Intake manifold mods?

#2

Post by Cotten » Wed Aug 25, 2010 2:48 am

chopped850 wrote:So has anyone modded the intake to better split the intake charge? Kinda like a shovel intake that has the triangular shape in the back to split the charge as it's forced into the heads? It just seems that the panhead intake tube could be modified at the flat back with some exrta material added kinds the same to split the charge. Just wondering as I didn't find anything in the search box. Also is it possible to adapt a shovel intake manifold and run the carb on the left side of the motor?
Chopped850!

Its a fun thought.
COBBMANI.jpg
The one at the bottom has a flange for modern carbs, and too short to run any way but off to the left.

It was less than an improvement, by the seat of my pants anyway.
Pans benefit from the velocity of a long intake tract, or something like that.

But it did look cool.

....Cotten
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kitabel
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Re: Intake manifold mods?

#3

Post by kitabel » Wed Aug 25, 2010 4:16 am

to split the charge

You mean like the factory did in 1936?
Didn't work - the "bad" manifold is the improvement over the split manifold.
It's not broke - don't fix it.

Bosheff
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Re: Intake manifold mods?

#4

Post by Bosheff » Wed Aug 25, 2010 7:44 am

If ya wanna run the carb on the left side, just mount the stock manifold facing the left. You may or may not want to shorten the manifold, cause the whole shootin match is gonna stick out a bunch....bosheff

Frankenstein
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Re: Intake manifold mods?

#5

Post by Frankenstein » Wed Aug 25, 2010 12:17 pm

As I understand it, it didn't work as well as the straight tube because the manifold/intake port act as a sort of plenum, and charge is actually moving from the closed port to the opening valve, as well as from the carb and it's runner.

DD

Cotten
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Re: Intake manifold mods?

#6

Post by Cotten » Wed Aug 25, 2010 2:06 pm

kitabel wrote:to split the charge

You mean like the factory did in 1936?
Didn't work - the "bad" manifold is the improvement over the split manifold.
It's not broke - don't fix it.
Kitable!

They did it long before '36, and so did Indian, Excelsior, etc.
JMNIFLDS.jpg
It is my opinion that with a large port, turbulence is better for seat-of-the-pants torque than 'splitting the charge". Face it, the 'charge' can only go to one open valve at a time; vacuum 'splits the charge', and a septum only takes up space to avoid a pressure drop that would let fuel 'puddle' out of suspension.

...Cotten
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Kuda
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Re: Intake manifold mods?

#7

Post by Kuda » Thu Sep 02, 2010 12:28 pm

Wow Cotton! Really diggin' that long jobbie on the upper left. While the more divided bottom may not work, I really like the idea of adding some radiator/cooling fins to the carb end. What a great idea! Gonna have to see if I've got a spare plumber's intake to play with now...

-Kuda (and enough clearance in there, too...)
'49 panchop

kitabel
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Re: Intake manifold mods?

#8

Post by kitabel » Thu Sep 02, 2010 5:58 pm

adding some radiator/cooling fins

Those are "heating fins".

Panshovevo
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Re: Intake manifold mods?

#9

Post by Panshovevo » Sun Sep 05, 2010 3:50 am

chopped850 wrote:So has anyone modded the intake to better split the intake charge? Kinda like a shovel intake that has the triangular shape in the back to split the charge as it's forced into the heads? It just seems that the panhead intake tube could be modified at the flat back with some exrta material added kinds the same to split the charge. Just wondering as I didn't find anything in the search box. Also is it possible to adapt a shovel intake manifold and run the carb on the left side of the motor?

I've wondered that myself, thanks for asking. And, thanks to all that responded.

I've also wondered if insulating the manifold would improve performance by reducing the heat transfer, thereby increasing the density of the incoming air (or I guess it would be more correct to say decreasing the degradation of the air density due to heating).

kitabel
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Re: Intake manifold mods?

#10

Post by kitabel » Sun Sep 05, 2010 5:38 am

Yes, that's what the asbestos gasket is for - to block heat from the manifold reaching the carb flange. With the original 1936-54 nuts you can't do anything about heat transfer from the heads, though. Manifold exterior surface can be chromed, or polished, then painted white or silver.

NightShift
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Re: Intake manifold mods?

#11

Post by NightShift » Sun Sep 05, 2010 2:33 pm

kitabel wrote:adding some radiator/cooling fins

Those are "heating fins".
Dear Kitable,
Heating might be good but they are hacksaw guides for the next change of flange pattern.

R'spectful,

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Re: Intake manifold mods?

#12

Post by awander » Tue Sep 07, 2010 3:58 am

I don;t get why you would need to "split" the charge, as only one cylinder is sucking at any given time. Right?

Panshovevo
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Re: Intake manifold mods?

#13

Post by Panshovevo » Tue Sep 07, 2010 2:48 pm

Any potential benefit would be gained not by "splitting the charge", but by easing the path the air/fuel mixture is forced to follow. Air has mass. Mass does not like to change direction once in motion.
Think about it this way. When riding your bike, you can take a sweeping curve much faster than a 90 degree curve.

Cotten
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Re: Intake manifold mods?

#14

Post by Cotten » Tue Sep 07, 2010 4:19 pm

kitabel wrote:Yes, that's what the asbestos gasket is for - to block heat from the manifold reaching the carb flange. With the original 1936-54 nuts you can't do anything about heat transfer from the heads, though. Manifold exterior surface can be chromed, or polished, then painted white or silver.
Kitabel!

The phenolic spacer was the primary heat barrier on Pans, not the metal-composite gaskets.

There used to be little way to reduce heat transfer from the heads on pre-Pan models, but today we have a great heat barrier: ferrules made of PEEK.

Chroming or polishing a manifold will only depreciate a valuable piece of hardware to a fraction of its original value, or ruin it completely.
Painting it white will only make it hard to keep clean.
The primary cooling agent is the vaporization of the fuel itself.
Some folks have even experienced icing!

Some very early machines actually had pre-heaters upon the manifolds to aid vaporization.

Think about it.

.....Cotten

Cotten
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Re: Intake manifold mods?

#15

Post by Cotten » Tue Sep 07, 2010 4:34 pm

Panshovevo wrote:Any potential benefit would be gained not by "splitting the charge", but by easing the path the air/fuel mixture is forced to follow. Air has mass. Mass does not like to change direction once in motion.
Think about it this way. When riding your bike, you can take a sweeping curve much faster than a 90 degree curve.
In addition,
slowing the flow, or widening the tract, allows vaporized fuel to condense out of suspension (puddling). Thus a septum or partition was used to take up space to keep velocity up.

In modern times an open plenum approach has become popular because of a higher overall volume capacity.

Our large-port Big Twins enjoy the best compromise of both.

.....Cotten

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