I need a custom-fabricated manifold..

Does anyone know of a place where I can get a custom manifold fabricated? I can't weld good enough to make one myself.

I'm adapting four Yamaha R1 motorcycle carburetors to a 1977 Porsche 924 (nee Audi 100) 2.0L 4-cylinder.

There's a British company that makes them

http://www.boggbros.co.uk/fabrication.html

but with our Dollar being only worth roughly a couple of Mexican Pesos to the British Pound, the manifold ends up costing $800 or so.

Call Alex at Neukin in Ft Wayne IN, 260 241 1703, he is an artist.

Tell him Steve sent you

If you can weld a little, then what I do is fab it up, tack it together, then bring it to a professional welder to finish it. There's a woman at the chicken plant manufacturer that is a real artist with a TIG.

Dr. Hess wrote: If you can weld a little, then what I do is fab it up, tack it together, then bring it to a professional welder to finish it. There's a woman at the chicken plant manufacturer that is a real artist with a TIG.

Dr. Hess has something here. People who work at food factories and deal with sanitary tubing a lot are usually some of the best I've seen at TIG. And they like side jobs.

Yah, a configuration like that is perfect, a single flat plate on the head side, and one or more flat plates on the carb/TB side, with short tubes connecting them. You can fab most of it with hand tools from Loews/Home Depot. A hand drill, a jigsaw, a hacksaw, some holesaws, sanding drums, hand files, a vise, and sandpaper. Order the material from online metals or somesuch (6061 is what you want).

Make sure the pieces fit perfectly, clean everything thoroughly, and find a pro to weld it together for you.

If need be, make a simple wooden jig to hold everything in alignment until it can be tacked, the weldor will appreciate that, and you will get exactly what you want.

Carter

Could you adapt a sidedraft weber intake? I have a sidedraft weber intake for my 924 that I'm not using. If you'd like some measurements from it, let me know and I'll pull it out of storage.

Not to rain on your parade, but unless you've gone nuts on the head porting, those big throttle bodies aren't gonna gain you much other than a loss of low end power.

I'm using a fuel rail and injectors from a Chrysler 2.2 turbo with the stock intake. We just have to bore the injector holes in the head to allow the injector o-rings to seat properly. If we can do this in our garage, any machine shop should be able to do it fairly easily.

Check out http://www.924.org for information and the message board at http://www.924board.org.

If you're looking for manifold parts for a fabricator to work from:

http://www.rossmachineracing.com/

Good luck! Stefan

fiat22turbo wrote: Not to rain on your parade, but unless you've gone nuts on the head porting, those big throttle bodies aren't gonna gain you much other than a loss of low end power.

Stefan,

I decided to go with the R1 carbs because:

I read a series of articles in European Car (they are 1996-ish back issues) on tuning the 924 engine. They threw every aftermarket part at it that they could, one at a time, incldung an extrude-honed manifold, big-valve head, a header and dual side draft Webers. They dyno tested every modification individually and determined that the only thing that netted them any power at all was the side draft Webers. They concluded that the stock intake manifold was the biggest restriction and that by doing away with it, it allowed the engine to breath and therefore make more power.

All that being said, Webers are $500+ for a pair and the manifold, if you can find one, is $300+. The Yamaha R1 carbs were a comparative bargain at $80 for the set! The car is painfully slow as it is, so I figure if the carbs work, great. If not, I'm not out a whole lot of money.

Ideally, I'd go with EFI (Megasquirt?) and individual throttle bodies, but I'm only shooting for 130hp or so while keeping it on a McBudget

72SuperBrian,

I was just curious, have you had a chance to put this set-up together yet?
I have talked to a few others that seemed to really like the results both on the vw and 924 board. I have also been looking into this set up as well. I have been looking at several sizes to make sure I do not get a set too large and loose too much low end power.
It seems like some of the weber dcoe 40 carbs have anywhere from 28-34or 36mm venturi, I would guess that a bike carb around that size (34 or 36) would keep low end power reasonable and still not top out too early. I think some people used 40 and 44mm carbs for higher output?

just my 2 cents - let me know how your set-up is coming along

sb924

Be aware that the best way to finsh the welding is with the new manifold bolted up to a head. If you can borrow a head to do this, you'll have much less chance of warping, and at least you'll know about it before you try and fit it to your engine.

Even so, you may have to have the flanges dressed or lightly planed for level.

What that engine clearly needs ain't some Japanese motorcycle carbs, it is a couple of 2" SUs.....

Here is a manifold I did out of aluminum for a tricarb MGC.(we also built headers for it).

I had heard they can be a little difficult to get situated - although I believe any multi carb set-up can be to a certain degree. It would certainly be an interesting and unique set up on the 924.
I did find a carb guy in New York that thought we might be able to get a couple of SU's to work. I think he mentioned 1-3/4" might be a good choice. Good guy - he seemed willing to help make it work.