Imo000

All he needs is an aluminium butt plug and a rubber hammer!

Jerry Feather

I'm not doing much on this intake right now since I am waiting on some more tube bends that I had to order a few days ago. I finally got around to cutting the last tube that I was saving for the very front tube, the one lettered "A," that was going to be cut kind of in a different way. I cut it in the different way, but made a mistake in doing so, so now it needs to be done over.

When I impose my overall cutting formula on the A tube and cut it it puts the bottom of the bell-mouth low enough to interfere with the slightly elevated base of the plenum. I could probably use it that way and just cut the bottom off of it, but I figured out that it can be cut a bit differently so that the inlet end is not so low. I calculated that since the beginning of the A tube is cut for the Hans base flange right at the beginning of the tube bend, I could cut it up the curve about 11.25 degrees, or one eighth of the 90 degrees total, which then rotates it so that the inlet end elevates above the plenum floor. So I cut it there. Then I cut the inlet end according to the formula used for the other 7 tubes.

However, what I found then was that the inlet end does not line up with the others by quite a bit. Then I realized that the reason for that is that when I cut the 11.25 degrees off the curve that also shortened the tube by about 9/16 inch, and that is about the amount that it doesn't now line up with the others. That's why I ordered some more bends so I can do it over.

It looks from the pictures that I will need to cut a new front A tube about an inch or so longer than the one shown that is too short. That will put the end pretty much in line with the others on that side and let the bell-mouth nest in the curvature of the B tube.

The front A tube is the only one that I can adjust in this manner since it is the only one which has the curvature right at the base flange. All the others have some straight tube between the flange and the curve or tube bend. Therefore, cutting anything off any of the rest of the tubes merely raises or lowers it and does not rotate it around the curvature as with tube A. I need the top of the curvature to remain on the plain of the tops of all of them.

Jerry Feather

Pictures of the topic of discussion always seem to be of great interest. I find that the pictures that I have posted of my progress are also of great benefit to me since I can sit in front of my computer and study them rather than standing in front of the intake as I have it mocked up to try to figure out certain things.

One of the things I am trying now to figure out now is why, when I hand place my bell-mouths at the ends of the tubes as presently cut and placed, they seem to get tighter in their respective nesting places as they progress from front to back. Each tube, except the front one, is cut on the base flange end across the straight segment of the tube, and the upper ends are also cut within the other straight section. Each tube rises by 5/16 of an inch taller than the tube immediately in front of it and 5/8 inch taller than the one in front of it on the same side of the manifold. Since they are rising at 22.5 degrees, the tops or apex of the curves at the top of each is getting closer to each other from side to side.

I cut the upper ends of the tubes off shorter by 1/4 inch with each successive one, but that does not seem like enough since the area where the bell mouth is supposed to nest seems to change too much as I move back. I think I am going to take another quarter inch off successively of the tubes on each side and see if that opens up the nesting place like I think it should be. That means that the second one on each side will be 1/4 inch shorter, the third one half inch and the rear one 3/4 inch shorter. From the pictures that looks like what I need to do.

Jerry Feather

Ah, the pictures really do help. I finally figured out why the bell-mouths are getting tighter within their respective "nests" as they move back. Not only are the tops of the bends getting closer to each other from side to side, and the inlet ends are getting shorter as they progress to the rear; but when the inlet ends get shorter, they are also getting taller because the cut moves up the inlet end of the tubes which are not level but at a 22.5 degree downward angle. That moves the bell-mouth upward a bit each time I cut off the inlet end.

I'm still going to study the upper ends to finally decide if they need to be cut off a bit more toward the rear.

Jerry Feather

I was waiting on the new tube bends to arrive before I worked on the intake again, and then they showed up about midday today. So, I made a little progress. First I turned the base stand I had fashioned into an actual stand. I did that by simply machining some legs for it and tapped them to screw onto the bolts holding the flanges down. Then I was able to take it all apart and drilled some holes to mount the TB under it and I cut a big chunk out of it in the back where I hope the MAF will fit.

Then I was able to refine the A tube in front to a suitable length. Then I re-measured all the other tubes and corrected their inlet length so that the ends pretty well line up with each other on each side.

Now I am ready to have the bell-mouths tack welded to the tubes and then I'll start making the plenum and the pattern for the openings on each side for the tubes to pass through.

Here are a few pictures.

Jerry Feather

At this point this intake may look like it is well on its way to being finished, but actually I think it is only a good start. I think it will meet my first criteria, and that is to fit under the hood. I have been trying to visualize the plenum, and have a pretty good general idea of what it will look like, but I have been unable to put the design down on paper. I think that is going to be sort of design as you go.

What I need to do next is develop some more tooling. I am going to fabricate the plenum out of .063 6061 T6 aluminum sheet and that is pretty hard stuff. I am going to need to fab a bend radius bar for one of my brakes. I think I'll work on that this morning, and if I work something up I'll make the plenum base plate. Then I can start making the patterns for the plenum sides which will have the tube openings in them.

Here is one picture of my attempt at a three view drawing of the plenum, but it is off quite a bit and I only got to two of the views. Instead of the rounded look that I put in my previous sketch, I think I am going with something more faceted. That's mainly because it will be easier to form and fit together with numerous flat surfaces instead of rounded, and I can form it easier than trying to find various large aluminum tubing to make the rounded sections.

Jerry Feather

I found a bend radius form that I had made some time ago that I thought would work even though it is a tighter radius than I was planning. However, when I set it up in my 24 inch brake I found that the sheet is too tough for me to bend in my brake. I'm going to have to have these bends done for me in a press brake..

I also find that I am still having trouble flaring the ends of three of my tubes. The end that is closest to, or in the bend, is work-hardened enough to make my system unsuccessful. What I am doing is placing my 2 inch steel ball in the end of the tube and hitting it with my mill draw bar wrench/hammer. However, because of the nature of the material and the bend in the middle of the work piece, I have to hold it in my other hand while I am striking it with the hammer. Otherwise I'll damage the tube if I try to place it on something solid. My hand hold is absorbing most of the hammer blow.

I think I'll go buy myself a dead-blow hammer and see if that will do the trick.

Ducman82

maybe i missed it, but why are the runners different lengths front to back?

Jerry Feather

Actually you cannot tell from the pictures that they are different lengths. In fact they could very well be the same length and not look any different than as shown.

I think what you are really asking is why are the runners in front not as tall as the ones in back? If that is your question, it is because the angle of the axis of the engine is not parallel to the under side of the hood, so, just as with the S4 intake, the front is short and the back it tall. They could all be short, but they cannot all be tall. Here, with the tall ones in the back I think there will be more room for the MAF to fit very close to its original position, or at least not so far off that I can't use it.

Ducman82

so the centerline of the runner length is all the same then? from the base plate to the opening? (san the bell mouths of course) . they do look to be longer/shorter in the front, and shorter/taller in the rear. thats why I'm asking. :-)

Jerry Feather

Not exactly, but very close. From front to back the runners increase in length of the bottom end by 5/16 inch each, and they also are shorter on the upper end by 1/4 inch progressively. I know it looks like much more, but it isn't. So the very front runner is only 7/16 of an inch shorter than the last one. I don't think you can see that difference in the pictures. But they are obviously much taller in the rear, by 2 3/16 inch. The reason is still the same.

Jerry Feather

Here are a couple of pictures of the S4 intake next to my project. This shows why mine slopes down back to front.

I think my runners are much closer to equal length that the S4 intake, although somewhat shorter overall.

Imo000

Heat up the aluminium and let it cool down on it's own, this will anneal it and make it soft again.

Jerry Feather

I like to make tooling when it is going to be helpful to do certain jobs and/or to help with accuracy. I made a simple piece of tooling to use by the welder when I take my tubes and bell-mouths to have them tack welded together. First the bell-mouth slips over it and then when the tube end is flared just right it slips over the top and they are automatically lined up for welding.

Jerry Feather

The morning before I left for surgery in the Denver area I left off a piece of aluminum sheet to be bent on the sides for the bottom of the plenum chamber. I was able to get out a bit and go by and pick it up yesterday and it looks perfect. I have some errands to run today and will need to go by the office for a while to return some calls and sign some things, but If I continue to improve in my pain and swelling I may be able to go out the the shop and take a picture of the plenum bottom approximately in place.

Then I can start laying out the shape and size of the plenum sides so I can take them to have them bent. I may also be able to fabricate the fitting pieces that will help me locate the holes that the tubes must pass through into the plenum. I pretty much have them designed in my mind and I think I can make them myself in the shop.

Here's the plenum bottom as it is bent, simple as it is. The aluminum alloy I am using is stiff enough that I could not bend it in my own brake.