Aluminum intake manifold

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chuck c

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I have a new intake manifold design. See what an armed and fully operational machine, sheet metal, & welding shop can do.
 

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Looks interesting,let us know how it works for you

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Looks like gas will puddle in plenum...why are runners not cut flush to box and extend inside box.
 
Some puddle room keeps small amounts of liquid gas from running into the cylinders. As the carb needs to be dialed in, I think that's a good idea. I've already dumped quite a bit of raw gas into my cylinders with the previous experiment. I've even considered adding a small fitting and bit if clear tubing on the bottom so I can see if any liquid is collecting.

The runners are beveled to point roughly towards the center. I don't think it will help flow a great deal but it's got to be better than a nearly right angle flow as it would be if the tubes were flush. That will also spread and disrupt the pluses coming back from the intake valves when they close. They won't be able to go down another runner.
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=181386#p181386:2dndruec said:
chuck c » Wed Sep 28, 2016 9:21 pm[/url]":2dndruec]
Some puddle room keeps small amounts of liquid gas from running into the cylinders. As the carb needs to be dialed in, I think that's a good idea. I've already dumped quite a bit of raw gas into my cylinders with the previous experiment. I've even considered adding a small fitting and bit if clear tubing on the bottom so I can see if any liquid is collecting.

The runners are beveled to point roughly towards the center. I don't think it will help flow a great deal but it's got to be better than a nearly right angle flow as it would be if the tubes were flush. That will also spread and disrupt the pluses coming back from the intake valves when they close. They won't be able to go down another runner.
Yes that is a very good idea
Bad idea. Opposite cylinder is on opposite stroke for a reason. But hey try it and prove the theory one way or the other.
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=181395#p181395:oolhqmx0 said:
chuck c » Thu Sep 29, 2016 4:58 am[/url]":eek:olhqmx0]
Not that is really matters much either way, why is that a bad idea?
Theory and perceived performance holds the fuel charge "bounces" back as intake is closed. Opposite cylinders is on exhaust stroke so draws it that direction as it begins the compression stroke. This adds more fuel and pressure (compression) to the fuel charge. It then bounces back to the other side. Interrupting the bounce or reducing the distance will reduce the compression of the fuel charge and alter how compression is gained prior to the next opening of the intake valve. It may even put the peak of the compression charge directly under the carb in the plenum at some point which may cause it to stall or backfire.
Yours is a different build and view of things. I suppose it is possible it will indeed work as you think. Or possibly the slashes on the ends may make no difference at all. There are a lot of very different manifolds in use now and all seem to perform very well once the carb is adjusted. So not saying you are wrong at all. Just giving theory and possible outcomes. At least you haven't put in any sort of check valve which would make a huge difference. :thanks:
Best wishes on this build and I'm following closely.
 
I understand about the intake valve pulses being used to help push mix into another cylinder, but even when that works, it only happens at a specific RPM or possible a few that are multiples. It's resonance and timing is critical or it can even work against you. I think this shape plenum. the offset of the runners, and the bevel will eliminate it so it will neither help NOR hurt.
 
Today, final weld and grind the flange flat. I originally planned the cable holder to be a separate steel bracket but it hit me that's foolish. There's no reason it can't be part of the flange itself. It only needs to be bent. I had to whip one up and have it welded on but future flanges will incorporate the throttle cable holding bracket. A part and two sets of hardware eliminated!

As I type it's getting chromate conversion coating. That makes it highly corrosion resistant and holds paint much better than bare aluminum. Tomorrow after work I'll paint it with the hammered finish black and saturday it goes on.
 

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This design will work just fine but it's pretty chunky and unattractive. It's the material I had available fast. I've drawn up another that's a bit nicer- looks less like some chunks of tubing sawed and welded together (which is exactly what this one is). That one is a bit more involved to make but it should be much cheaper. This one takes $50 in material alone when bought in small amounts. My next one looks nicer and costs less. I plan to offer it for sale. Price is yet to be determined.
 
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