davek9

I own both an 85 & 86.5, they are all the same, as Jerry stated due to the size of the upper air box (lid). Necessary to clear the wide intake plenum.

To avoid breaking the air box lid, remove the fender cross brace first, then you won't stress the plastic parts.

I used my spare set of tubes on my 86.5 as the ones that came with the car were trashed and all duct taped up

Would like to have another set to run, and squirrel away the OEM's

Thanks Jerry for moving forward on this.

Dave K

Jerry Feather

The tube I took out of my 85 is right at 26 inches long at about the centerline. So, I am going to cut my boards into 29 inch lengths and then rip each piece into three strips a little over 1 inch wide leaving the last part of each at about an inch and a half. Then I will have to glue some of the strips together with epoxy. When they cure I'll refine my milling so that I can mill the combo pieces to their finish sizes and shapes to start turning.

You can look at one of the drawings and figure out which joint will be glued and which will not. The center piece will be 1 by 1 and then will have to have a hole about a half inch more or less down its center longways. That will be for the vacuum. I haven't figured out yet just how to drill the hole 29 inches long.

When all the pieces are milled to finish I'll bundle them together in the final configuration, with wax paper in between them, which I'll explain later, and clamp the bundle in several places with hose clamps. Then the bundle will be turned in the lathe to make the form.

I'll try to show these steps as I go.

Alan

I can see the attraction for the large intake plenum models where there aren't many other options - but thats a rather small market. For the other models with larger (symmetrical) ports and more space I think there are sufficiently good and inexpensive varied options already available.

I'm a big supporter of what you do Jerry - but I'm not sure this one will be a big success financially for you. Seems to me it will be complex for you to make and quite low volume. The tubes need to flex longitudinally so the longways tube seal needs to survive that - tricky for the long haul...

Personally I'd rather see you do a few other things first - my list of ideas:

1) New sunroof internal cover (mine is badly warped due to cover shrinkage - assume others are too), better attach mount
2) New sunroof drip tray (most seem to have warped/cracked)
3) Console side panels (for carpet covering)
4) An insulated cowl over the radiator as a cooler air feeder for the intake tubes
5) New front splash shields (with a bit more flexibility to avoid cracking)

Just telling it as I see it.

Alan

Jerry Feather

Thanks, Alan. All good points and suggestions. I'll take them under advisement.

SMTCapeCod

I recal the threads regarding the pinch point and the notion of turbulence mgt/venturi vs. sound control. Surprising to me that it does much to reduce sound- based on non-928 experiences changing a few cars from fully enclosed to open-element air cleaners, I'd be up for a noisy version...

UncleMaz

Jerry, Thank you for considering making this NLA part for the "S3" cars. Owners of these cars are painfully aware of its limited market and the scarcity of certain parts, especially principally non-cosmetic parts such as intake tubes.

In the end analysis, I hope it makes enough business sense for you to make them.

byrdman454

Another part that has been NLA for a while are the pre-S4 bumper plugs. One of these cover the tow hook mount in the front. 928 INTL is also out of used stock at the moment. These covers are getting so old that they basically break parts during removal. Not sure what it would take to re-make these but it would be nice to have another option (unless someone has a suitable replacement that I don't know of).

Bilal928S4

Coming into this thread late.
Wouldn't just making an adapter that would let the S4 tubes work with these cars be more beneficial?

Avar928

I believe the S4 tubes won't clear under the engine cross bar. They'll just get squashed.

Alan

Maybe - but it has to fit in this much more restricted space (and bend more in a particular spot), Vertical clearance is also limited by the rest of the intake you can't see:



Alan

Tony

Put your air filter in the fender where the washer fluid res. is and you will hear what a noisy intake sounds like. Mine sounds like its going to suck in the passenger.

77tony

https://rennlist.com/forums/928-foru...-plug-fix.html

Jerry Feather

I started the process of processing the wood for the form. I first cut my boards into 29 inch lengths then ripped most of them down to a little over an inch wide for most of them leaving four pieces over an inch and a half.

Then I glued the pairs together with epoxy and am letting it cure. It is slow, so I wont get back to these probably until tomorrow. I had to gather up all the unassigned clamps I could find for this task, but it all came out even.

Here is a picture of my future vacuum sump.

Ketchmi

Have you considered making an airbox lid that would clear the 85/86' intake and use 87'-later tube sizes since they are still available? Just a thought...

Jerry Feather

I have some thoughts along those lines, but not quite that one. My first thought about that idea is that if that were an option I think one could just put the later airbox lid on the box. In fact, I think that is what might be the case for someone in this thread who says he has an 86.5 with the later 3 inch openings. I think that the limitation for the 85 and 86 cars is the space along side the intake plenum and that that is what limits the size of the opening in the air box lid.

My thought about making a different air box lid with larger openings than the 2 3/4 inches they now have is to make the opening narrow and tall and then make an air tube that is also narrow and tall at the outlet end to match. I think that might fit the space and still allow a larger air passage.

The limitation is how to make a form for the tubes in that shape since I don't have a CNC wood lathe. I might figure out a way to do it if and when I get to it.

I think my next step in this project, if this current tube idea even works, is to make a replacement for the original tubes and that will be suitable for the GTSs.