# Porsche 928 CIS Questions



## suburbangeorge (Apr 24, 2004)

This is not quite on topic since a Porsche is not an Audi or VW. Years ago I noted the similarities between my Scirocco's CIS and the mechanical Rochester Corvette fuel injection. Often day dreamed about some system using two fuel distributors on a chevy V8. The other day I was looking at a VW & Porsche magizine from 1979. One article was about the "new" 928. It used CIS. These things are starting to show up in local Pick n Pulls. A system set up for a V8 would be a huge head start toward having CIS on my 66 Suburban. What I'm looking for is info such as the fuel system section of a 928 Porsche shop manual. Anyone done anything like this? Thanks, George


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## ABA Scirocco (May 30, 2001)

*Re: Porsche 928 CIS Questions (suburbangeorge)*

Merecedes Benz used CIS or CIS-e for many years right up to the early 90's, that might be an easier place to look for an 8 cylinder system.


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## suburbangeorge (Apr 24, 2004)

*Re: Porsche 928 CIS Questions (ABA Scirocco)*

Thanks.


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## suburbangeorge (Apr 24, 2004)

*Re: Porsche 928 CIS Questions (suburbangeorge)*

http://****************.com/smile/emthup.gif


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## Jade Wombat (Oct 20, 2004)

*Re: Porsche 928 CIS Questions (suburbangeorge)*

Ferrari used two six cylinder units on their 12 cylinder units for a while I believe. The Testarossa I think it was, Miami Vice car(the 2nd one, the white one).


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## ABA Scirocco (May 30, 2001)

*Re: Porsche 928 CIS Questions (Jade Wombat)*


_Quote, originally posted by *Jade Wombat* »_Ferrari used two six cylinder units on their 12 cylinder units for a while I believe. The Testarossa I think it was, Miami Vice car(the 2nd one, the white one).

I've been thinking about something like that, it might be cool to open the hood of 66 Suburban to see an intake manifold something like this with two gracefully curved CF charge tubes, mirror images of each other, each leading from the throttle body to a CIS unit neatly tucked into the fender. To pull off the look, you'd have to find someone that could make custom braided injector fuel lines for you. I have know idea how well it would work, but it would be cool look, a weird Europe meets Detroit, modern/retro blend.


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## suburbangeorge (Apr 24, 2004)

*Re: Porsche 928 CIS Questions (ABA Scirocco)*

Actually I was more interested in function over form. Had the old Rochester system on my Chevy powered Healey back in the early 70s.
Other than one problem, it performed flawlessly and provided much better gas mileage. Problem was(I found out after I had sold it for a couple of $100 and a new aluminum intake) it was a race unit. It had no provision for cold starts. I trained myself to put my right leg over in the passenger's footwell so as not to blip the throttle while starting and loose the existing gas charge. After sitting 24 hrs+ even that wouldn't work. Had to open the hood, disconnect a splice in the fuel line, remove the air cleaner, stick the fuel line through the butterfly, turn the key to operate the fuel pump to prime it and then put it all back together before starting it! I got good at this and could do it in a couple of minutes but what a pain! The company that printed GM's manuals was on strike and this was the 1963-1965 system(different from earlier) and I couldn't find one in a library. So I gave up. Now I know how to fix it but existing ones are $4000-5000.
Enter the Porsche CIS system. As an inprovement on the old Rochester, it would have a cold start injector, an oxygen sensor for mixture control but none of the unwanted emission functions of the later electronic Corvette systems. Those are so complicated that a plug and play harness that allows use in any car costs around $1000. Also I figured that the V8 configuration would be similar enough that I could use the Porsche braided lines(I hope). Still would have to add provision for CIS injectors to a Chevy, aftermarket or custom intake but that would be doable. Am just hoping that I find someone who has already done it,


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## ABA Scirocco (May 30, 2001)

*Re: Porsche 928 CIS Questions (suburbangeorge)*


_Quote, originally posted by *suburbangeorge* »_Actually I was more interested in function over form. 

In that case, definitely have a look at some of the Benz units. I was looking at one a couple weeks ago, a CIS-e unit, it's a down draft unit that mounts right about where you'd normally expect to see a 4 barrel carb, a very neat, compact installation that probably wouldn't be all that tough to adapt to a Chevy V8. Unfortunately, I didn't take note of where the cold start valve(s). was located.










_Modified by ABA Scirocco at 12:58 PM 2-23-2008_


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## epjetta (Sep 19, 2006)

*Re: Porsche 928 CIS Questions (suburbangeorge)*

i think it would be way easier to install a megasquirt in your chevy. will run better on it for sure whwn compared to a 20yr old cis setup. i plan on doing just this on my sb dodge for my 4x4 rabbit truck.


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## Mk1Racer (Apr 16, 1999)

*Re: Porsche 928 CIS Questions (Jade Wombat)*


_Quote, originally posted by *Jade Wombat* »_Ferrari used two six cylinder units on their 12 cylinder units for a while I believe. The Testarossa I think it was, Miami Vice car(the 2nd one, the white one).












_Modified by Mk1Racer at 6:14 PM 2-25-2008_


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## Jade Wombat (Oct 20, 2004)

*Re: Porsche 928 CIS Questions (Mk1Racer)*

Nice photo. I would disagree about setting up a SB with Megasquirt. MS is cheap and easy to use and more 'tuneable' than CIS, but it doesn't sound like you were after max hp anyway. Unless you have the manifold and fuel rails for pulsed injectors(like off a Camaro or something), doing a standalone system could get expensive real quick. CIS can be had for almost nothing and runs very well. Fab up your own injector brackets and you're in business. 
My Golf I've had for 11 years and 200K has ran like a top the whole time, only minor BS I've had to deal with like the pump housing leaking.


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## suburbangeorge (Apr 24, 2004)

*Re: Porsche 928 CIS Questions (Jade Wombat)*


_Quote, originally posted by *Jade Wombat* »_Nice photo. I would disagree about setting up a SB with Megasquirt. MS is cheap and easy to use and more 'tuneable' than CIS, but it doesn't sound like you were after max hp anyway. Unless you have the manifold and fuel rails for pulsed injectors(like off a Camaro or something), doing a standalone system could get expensive real quick. CIS can be had for almost nothing and runs very well. Fab up your own injector brackets and you're in business. 
My Golf I've had for 11 years and 200K has ran like a top the whole time, only minor BS I've had to deal with like the pump housing leaking. 

you are so right! In the case of the Suburban, I will be replacing a 327(which was more than enough power) with a 383 and in the case of the V8 Healey, I could burn off tires for as long as I kept my foot in it. In both cases I am looking for better milage and drivability.


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## tristessa (Sep 25, 2003)

*Re: Porsche 928 CIS Questions (ABA Scirocco)*


_Quote, originally posted by *ABA Scirocco* »_To pull off the look, you'd have to find someone that could make custom braided injector fuel lines for you.

Make them yourself, it's not hard. Re-use the fittings from the factory hoses (heat the ends with a propane torch to get 'em out) and use A/N -3 teflon hose. I had to make two longer hoses for the CIS setup in my '75 Westy (2.0L aircooled flat-four), they've been working just fine on a daily basis for the last two months. Putting them together was easier than finding -3 hose without resorting to mail-order.


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## ABA Scirocco (May 30, 2001)

*Re: Porsche 928 CIS Questions (tristessa)*

Good to know, I just might use that someday. http://****************.com/smile/emthup.gif


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## tristessa (Sep 25, 2003)

There's one "gotcha" to making up new lines I forgot to mention. Most of the CIS lines I scavenged for the fittings had a larger outer diameter than the Aeroquip -3 hose I used for the new lines, so the ferrule sleeves are too big. Only lines I had with the right size sleeves were a CSV line and one of the two that runs to the WUR/CPR. Inner diameter was the same on all of them, so it didn't matter where the ends came from. 
Putting the end in is pretty easy, here's how:
Make up a jig for putting the ends in; clamp a couple pieces of 1x2 (wood) in a vice, drill a hole through where the edges meet. Unclamp the wood, put the hose end through the hole with enough sticking up so it reaches the inside end of the sleeve, and the bottom of the sleeve rests on the wood. Clamp the blocks (with the hose in them!) back in the vice, put the fitting into the end of the hose and smack it home with a wooden mallet, block of 2x4, whatever .. just don't hit the fitting with a metal hammer. I had to use a piece of dowel as a drift to get the injector ends in, the nut part kept me from getting the inner part all the way home with the mallet by itself. Takes a few good whacks, but once it's in that fitting ain't goin' noplace. 
General rules for working with stainless braid hose apply, but those are easy to find.










_Modified by tristessa at 12:51 AM 3-3-2008_


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## suburbangeorge (Apr 24, 2004)

*Re: (tristessa)*

Thanks for all the info.


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## ABA Scirocco (May 30, 2001)

*Re: (suburbangeorge)*

BTW, here's a picture of a Merecedes Benz 6.9L V8 with CIS. This picture was taken for the book "Bosch Fuel Injection Systems" by Forbes Aird












_Modified by ABA Scirocco at 10:41 AM 3-7-2008_


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## suburbangeorge (Apr 24, 2004)

*Re: (ABA Scirocco)*

Took a look at one of the Mercedes set ups the other day at Pick n Pull. It appears that the intake manifold would have to seal to the entire fuel distributor. Thats what interested me in the 928. A throttle body on the intake and a stand alone fuel distributor would require less fabrication. When I have more time, I'm going to pull the Mercedes system apart and see what's what. Thanks for the imput.


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## Longitudinal (Nov 13, 2004)

*Re: (suburbangeorge)*

If it helps anybody's effort to build a CIS V8, I offer the following information:
Fuel lines can be a problem, but when I built an 8VT setup with eight injectors and a MB V8 CIS-E fuel distributor, I found a trick.
Late Audi CIS-E cars have tube nut connections at the FD just like the MB, but the tube nuts have thicker heads--thick enough to center drill and tap. I cut up some fuel lines at a local JY and center drilled and tapped them for 8*1mm banjo bolts so I could use regular VW CIS injector hoses. It all went together perfectly and never leaked.
These Audi tube nuts could be drilled and tapped to something that works well with AN.
Oh, I also saved small portions of the fuel line compression fittings from the Audi. I saved only a short piece of line, just long enough to hold the compression fitting in place so everything would seal up. 
Does this make sense and maybe help with the V8 plans? I am all for CIS conversions on anything. It's a great system in all of its iterations.


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