CIS expert questions
 

Hi all, I wonder how many of you out there are familiar with bothe the 911 CIS system as well as the VW (rabbit/golf) CIS system

what are the similarities/differences?

I'm building a 914 engine to go in my beetle, and I'm going to run a CIS system from a rabbit, on it and wondering if there would be some parts from the 911 that would do a better job on this engine than the vw counterparts, such as the warm up regulator.
I'll need to use the VW fuel distributor since its set up for 4 cyl's rather than 6.

CIS? What's wrong with D or L Jetronic?

I did the CIS conversion on my 914, it ran (still does) great. Use all of the CIS components form the Rabbit, they are all matched for that system. Mixing and matching can cause all sorts of greif.

You can check out the Excellence article on my old 914 on my webshots page. See link below.

Good luck,
Ed

Re: CIS expert questions
 

That's a tough call. Originally, things like the shape of the air flow sensor funnel and characteristics of the control pressure regulator (aka 'WUR') were developed by Bosch for specific OEM applications. You might do best by selecting components from a VW that most closely mimics your displacement and powerband charateristics, but that's really a guess. A 911 control pressure regulator (for air-cooled application) might work better on a 914. ?????
Good luck!
Edit: looks like "evill" beat me to the punch -- nothing like the voice of experience!

thanks, This helps a lot.

Looking really good, I love bug projects. Good luck with yours. Let me know if you run into any hassles or have any questions when you set up the CIS on your 1.7 T4.

Ed

I have a 78SC with CIS and years ago had a Rabbit with the CIS system. The basic systems (fuel distributer, WUR, AAR and injectors) are essentially the same. Porsche adds things like the deceleration valve to prevent closed throttle stalling, AAV to help starting, and thermo valve for warmup. The WUR vacuum plumbing is an issue as well. If I recall the Rabbit had no vacuum lines. I agree with evill, don't mix and match...take an entire system from a similar displacement engine.

The CIS system is actually a very good, simple, reliable system that has unfortunately acquired a bad reputation by having too many "1/4 turn" tuners screw with it.

I've had many VW's with this system. Tuned by someone who knows what they're doing, it is a great system to run, CIS-E on the other hand took a simple system and overcomplicated it, making it no where near as good.

Ya I have a complete system from a rabbit that should do nicely. I have been considering using the warm up regulator from a audi 5000t and making use of a supercharger that I have kicking around, from a toyota 4agze, on this engine, but its a prety lumpy cam, so It might just blow most of the fuel out the exhaust.