After having worked on many mercedes and older bmw's with the Non-computer CIS I became convinced of the properties of the system.

Who here has actually swapped a CIS from a donor? What was the Donor? And how did it all work out for you?

Cheers:

Been there, done that and I love it..

Its good to 160HP and thats it.. Look on the about us page of my site and then "Jake's cars" to see it in my bus...

I have not adjusted it in 55+K miles... Gobs of torque and I dynoed it down to 500 RPM..
If you want hi revs its not for you. Its all about torque.

I used a Rabbit fuel dizzy to begin with, then I swapped to a Scirocco for 15HP difference on the dyno. I also use 930 injectors..

Its easy to do- I can help..

Jake, your the man!!!

That is exactly what I am after---The TORQUES.

I already sent my heads to Len---Is there anything he should do to them that I am not aware???

Have a Red Stripe on me> -- if you are a non-drinker--have a root beer!!

Len knows CIS as well...

You'll need help on the cam. I use a split lobe center arrangement for CIS, the intake event is very critical to the way the flap meters the fuel. That flap needs solid, constant vacuum to do its job smoothly. If you have too much cam on the intake side things go to hell quick.

I too have wondered about this. I have 3 or 4 complete injection systems from Rabbits, so I should have all the parts. Did you use the original intake runners and intake? Where did you put the injectors? Just into the original injector holes? Sounds like there would be a bit of fab work involved. What other advice do you have, Jake?

Thanks,

I had the impression that the K-Jet swap was a very limited option because of the design of the flapper housing. That if you really wanted to optimize a K-Jet install you needed to havea custom housing made. The profile of the housing as the flapper moves down/up the bore widens at a particular rate.



I've always loved the simplicity of K-Jet. Kinda like Carbs of steroids.

CIS rocks...I used CIS-E off a 5 cyl Audi motor on my '74 turbo



Couple of pics of how I did it in this thread

This is all very interesting. I am now very inclined to move my project from dual carb turbo to CIS turbo

I know the 70-80's 930's used basically the same system as a big cube mercedes, the fuel divider had two of its holes not even drilled for the 6 cyl. Porsche motor.

Those cars are very plentiful for donors, just down the street from me at u-pull-it.

Good thing I spent several years working on these beasts to know what I am looking at.

Thanks all-

Hmm... so what could you do to a Type-4 to make some better HP utilizing CIS.

Without spending $10K on the engine?

Cams and CIS?

Better breathing and CIS

P&Cs

Stroke?

A turbo and CIS. Normally-aspirated, CIS is a nice reliable system, but it's not a way to unlock big power over D-Jet. CIS has serious cam restrictions. A big engine and a mild cam, or a turbo and a mild cam. Wild cams and CIS don't work well together.

So,,,who here knows the intake cam lobe profile as used on a factory Porsche 930 turbo with the CIS?????

If they nailed it----Should be worth looking at as to comparing the 930 cylinder head flow rate and a type IV with improved intake flow numbers............................

Any more thoughts on this??????????????????

it's not the intake you need to be worring about

from what it sounds like from Jake, the exhaust side is the biggest limiting factor

I'll be using the original CIS on my 2.7 /6 motor, but I was told to use the SC cams for best results. Call Elgin in Redwood City (?) for profile questions. They could even do the work for you. Or talk to John Daugherty who works at Elgin, he will do them cheaper. According to the 911 crowd, it is as Jake said, CIS needs steady vaccume to work properly. If you have too wild of a cam it will cause pulsation in the flap, basically confusing the system. And I have heard tale of such a cam forming a vapor cloud of gas over the intake. The 911 engine builders forum on the bird board is a good resource for CIS questions as these guys have tried a lot of things with CIS, + turbo, + wild cam, etc.
HTH