Does anyone have a source for a custom cold air intake system for a 1987 928 S4? I want to replace the plastic tubes with a polished metal tube system. I would like to leave the plastic plenum in place if possible.

Thanks

 

Its been done, they get hotter than the plastic. No one sells a finished product at this time.

 

Rick--

A few folks have used hose and various industrial tubings, but that's more an appearance than performance issue. They were replacing frag'd plastic pipes or the 'insulated' GTS tubes. As mentioned, you really want the tubes to insulate for both thermal and acoustical reasons, so metal tubes might be your last choice. The tubes see radiated heat from the heads and exhaust. Porsche dsaw fit to add a layer of insulating material to the GTS version of the tubes to try to muffle the intake noises some. Again, metal would not be the choice for this.

Many users have traded for the tubes used on some Mercedes cars, and saved some $$ over new 928 bits. No venturi so no sonic effects, but a series of straight and ribbed sections that look at home under the hood. I'm sure someone will post more info on those if you ask.

 

Actually, the 928 intake set up IS a cold air intake system. Out of all of the trial and error I have seen, I think Porken came up with the best set up by using heavy rubber matting and channeling the cold air directly to the intake tube. Although this is pretty much the way it's done by the factory, Ken took it another step and honed in on directional flow. He separated the cold air from any heat radiating source. Even though there is rubber molding on the intake/radiator header which seals airflow at the hood when closed, there is heat stagnating to some degree in that void. Ken has done his own trial and error and aside from his other "engine cooling" idea's, he seems to feel his minor modification helps the cause.

 

Power adder makes a plastic modular set that is "chromed". FIts to stock airbox with a 3" union. Can add cone fiolters or antoher 3" union to stock intakes. I had them in my sig pic below, just painted metallic red.

 

Since we have two threads on this....

I'm not sure of any that made it to the market. Performance gains are questionable, they do look awesome.

airosey had his own made:
https://rennlist.com/forums/928-foru...ubes-pics.html

ceedee looked into making a set, not sure where that project went:
https://rennlist.com/forums/928-foru...ake-tubes.html

 

Ceedee copied the ones from airosey and even used airoseys engine pic in his ebay ad. He got his hand slapped and stopped using the pic. After making a couple of sets he quit making them.

He just took the pics poste in airoseys thread and his car to a fab shop and had them make them out of stainless tubing. Its a pretty easy project if you can weld or if you have access to a fab shop. Don't expect any performance gains do to the heating of the air. If you do decide to do this. Please do a before and after dyno so that we can put this issue to rest once and for all.

Thanks

 

+1

 

Here's a design I came up with for my '84 Euro. Could be made to work with the earlier "barn door" style US models. Don't know about the 85-86 US setup. For the S4-later, it would be a different design altogether.

Haven't had time or money to develop it further, but will.

 

Porken proved that there was benifit to be gained by not letting the heat from the radiator get to the intake air. I tried to take it to the next step, because (no offense Ken) his piece of rubber is down right ugly. Mine is fiberglass and extends the inlet scoops out over the radiator. The pictures below don't show the final product as I still have some fiberglass work to do and also to insulate the center section which is currently hollow.

Jadz928 That intake system is just beautiful! If you ever get around to producing them I want on the list.

I'm on Dave Robert's list for his "Blackbird" but he hasn't announced any delivery dates so who knows when production will begin.

 

Nice modelling, Jim! Those flexible bits must have been difficult.

I'd take offense, but only 'fancy' folk care what it looks like under the hood.

BTW, that looks cool. If you could make that out of flexible plastic, it'd be schweet, and factorish.

I think any cover should extend >3/4" past the radiators, to force air to go up and around?

 

Thanks Ken. Flex parts aren't that bad with he right tools.

Jim, that is a really cool looking piece there! I like it, just wish I had the fibreglassing skills.

Hout about we use your piece as a master and make silicone molds out it, then cast a few in a urethane?

 

Can someone come with a custom design for Andy Keel's supercharger?

 

perfect place for some carbon fibre tubing.


We were looking at making this, have something like 30 feet of the stuff, but unfinished.

 

Roger at 928s-R-Us is looking at doing exactly that. But we discovered that we would need at least three different versions. The early S4 5 speeds don't have the oil cooler at the top front of the radiator, the OB's are different and anyone with a Devek aluminum radiator has the small return tube welded in a odd angle that will cause some interference. It's never easy.

On the other hand, fiberglass is easy! Cast/form what you think you want and sand away what you don't want. I enjoy working with it (except for all the dust).