FI & Turbo Friend or foe

Trebor · Post by **Trebor** » Tue Aug 21, 2001 7:26 pm

I heard today that the FI in a vw rabbit 93 and newer will work with a turbo with up to 15 lbs of boost. Can anybody confirm this? Is the rabbits manifold under positive pressure?

Robert

GDRBO · Post by **GDRBO** » Wed Aug 22, 2001 5:47 am

Gary Miller, @www.millerfi.com, has been working on adapting CIS for use with turbos. I believe he is using the early form but he may be familiar with the later version.

ray greenwood · Post by **ray greenwood** » Wed Aug 22, 2001 7:52 am

I can't remember if that year is digifant or motronic injection. Both have a huge range of after-market parts available with lots of turbo cars out there. Take a look at what swims through the pages of European car magazine. If I am remebering correctly (correct me if I'm wrong) the motronic controls ignition and advance also, and it has only been the last two years that acceptable after market chips have been available for that injection, that could handle all of the parameters. I think there are three tuning companies that do them...and all of them have to have your box on premises to do the mods. I also know that all of the modern injection systems have a myriad of exhaust systems, throttle bodies, power chips, superchargers, turbo-chargers and ignition systems available on the aftermarket and TUV approved . The tuners and manufacturers of these systems are incredibly knowlagable, from my experience and can probably easily answer your questions and supply you with the correct parts...and set up... for this injection on an air cooled car. Seriously, pick up a copy of european car. Ray

Trebor · Post by **Trebor** » Wed Aug 22, 2001 9:02 am

Hi Ray, I am considering a rabbit FI for a type 4 turbo charged sand rail. I wanted to confirm that the injection system would work on this application before I started digging for parts in a wrecking yard.

Robert

ray greenwood · Post by **ray greenwood** » Wed Aug 22, 2001 5:09 pm

The CIS lends itself much easier to turbocharging because the fuel metering plate is not really subject to differential pressures like a MPC on the D-type electronic, and is much more rugged and adjustable than the L-type swinging vane mass air flow sensor. The extra volume will lift the plate/arm to a correspondingly higher level of enrichment. It will usually lift it too high on a system not designed for a turbo charger, but this is not that hard to adjust around. Early rabbit CIS is fairly simple. Be sure to get the Lambda box and harness...if it has one. Count on the injectors being shot...either from age or rust,. There will be a 50/50 chance that the fuel distributor is shot also from rust. So look for an engine from a car that has driven as recently as possible. I just saw a link a few weeks ago to a web site..here on the forum from someone who specialises in CIS on type four. You might want to look at that. Manifolds and central placment of the fuel metering plate will be the first challenge. Almost any throttle body that you desire can be used with CIS...and there are hundereds from almost any injection system..either electronic or CIS to choose from. Size is your first decision....after all, the throttle body does no metering on this injection. It is only a general volume control...the plate does all the metering. the throttle valve needs to be placed far enough away from the metering plate to keep spikes in air flow away from the plate, but close enough for quick response without a lot of velocity loss. Almost all of them are twin opening, progressive. You could start with a rabbit system , and add a larger fuel distributor from a larger engine...or stay with one system and use fuel enrichment devices. For example, the saab 900 uses a rising rate fuel pressure system...which is nothing but a fifth injector constantly bleeding fuel pressure off. During heavy load...the lambda unit with input fom the oxygen sensor adjusts the pulse rate of the 5th injector up and down to vary the fuel pressure. It also has a max-load vacume switch for passing downshifts, which can simultaneously stop the pressure bleed on the 5th injector for max enrichment and also actuate the cold-start injector for additional enrichment (thats on the turbo model)...all are really simple switches. The key to getting CSI running correctly is starting at the gas tank...with your pressure guages and making sure that every part, and every check valve is operating properly and at the right pressures...simple, but tedious. The coolest thing about most CIS cars...with lambda...is that there will somewhere be...a two wire plug...in the engine compartment. You can plug in to with any voltage ohmmeter with a duty cycle function, while the car is running...and it will give you the pulse cycle to tell you if the engine is running in the correct air/fuel ratio...very much like a CO meter (as long as everything is functioning correctly). I can check correct fuel mixture on my 83 SAAB by popping the hood, plugging in and reading the # and comparing to the book...simple. Ray

Dave_Darling · Post by **Dave_Darling** » Wed Aug 22, 2001 7:27 pm

CIS Turbo Type IV motor: http://www.rennlist.com/edvturbo .

If you ignore the silliness, there are pics of the actual CIS turbo setup.

So--Yes it has been done. Ed used Miller's FI, from the link posted earlier.

--DD

Evill Ed · Post by **Evill Ed** » Thu Aug 23, 2001 5:47 am

Dave, your link did not work, I think it needs the .htm added to the end.

Try this one http://www.rennlist.com/edvturbo.htm

Ed

ray greenwood · Post by **ray greenwood** » Thu Aug 23, 2001 1:04 pm

Thanks for the link Dave...and I skimmed right over it in the earlier post. It looks very complete. Interesting manifolds...Just plumbing the CIS is a challenge...working it with a turbo is a lot of R&D. I'd like to find out if he got it running with CIS first and turbo later...or if they were done simultaneously. Ray

Evill Ed · Post by **Evill Ed** » Thu Aug 23, 2001 3:02 pm

Ray, that is my 914. I did the CIS first, and then the turbo. In both cases I got lucky and the engine ran well with minimal fuss.

Ed
http://members.rennlist.com/evill/ed1.htm

CIS PAGE

Dave_Darling · Post by **Dave_Darling** » Thu Aug 23, 2001 3:38 pm

Thanks for the catch, Ed! I must'a had some brain fade when typing in the URL...

--DD

------------------
1974 VW-Porsche 914; 2.0 liter Type IV motor

ray greenwood · Post by **ray greenwood** » Thu Aug 23, 2001 3:45 pm

Thanks for the info Ed. I will probably have some questions for you at some point. That's a big undertaking. I wondered years ago on my first 411 if CIS would be possible....I was thrilled with the thought of having FI without having to deal with the wiring harness issues I was having. Ray

danerius · Post by **danerius** » Fri Aug 24, 2001 2:06 am

Ed. What CIS did you use. Im planning on one for my two litre type four?

Evill Ed · Post by **Evill Ed** » Fri Aug 24, 2001 5:56 am

My CIS was purchased from Gary Miller, it is from an early Rabbit, 1980-ish.

Ed

Bruce M · Post by **Bruce M** » Fri Aug 24, 2001 6:11 am

CIS with possible turbo is the path I am planning to use. I have done a far bit of reading up. The millerfi site is a very good start, then get the bentley manual.

Personally , I don't like the lambda versions. I feel that running the mixture around the stoic. ratio is a bit lean for aircooled motors, especially with a turbo.

The usual enrichment system for turbos uses a special warm up reg. The increase in manifold pressure reduces the resisting force on the plunger in the fuel dist. so the flap goes further with the same air flow.

The lambda system varies the fuel pressure in the bottom of the fuel distributer changing the pressure drop across the metering fuel slits. The pressure is constantly changing to cycle the mixture from rich to lean around the stoic ratio.

As Ray says , it all about the fuel pressures. Make sure the lines are made right. The pressure the system uses is very high (higher than pulsed injection)

Don't forget the 924 carrera GT made 210 bhp with a 2ltr VW van engine using CIS. The race versions made up to 375bhp (don't know if they kept the CIS though).

[This message has been edited by Bruce M (edited 08-24-2001).]

ray greenwood · Post by **ray greenwood** » Fri Aug 24, 2001 12:38 pm

I think that was a good point made about pressure of fuel resisting the plunger...and therefore not using the lambda box. Good thought. What you could also do is to look for a control pressure regulator that employs a higher control pressure. That would also help keep the plunger stable. I also think that most rising rate pressure regulators...no matter what kind of injection, all suffer from having diaphram pressures..in both directions...and vacume break points that bear little relation to what is going on to the engine load cycle. They are usually either in...or out. I have one reg. off of a mercedes I believe, that I am testing. It is a Bosch rising rate plumbed for CIS...with an adjustable vacume diaphram..for setting its sensitivity to vacume. I think set fuel rate on the main ring is more reliable. The lambda box could control enrichment through a secondary injector...additive only. Not like the frequency valve/pressure bleed version. Saab turbos used a combination of both...slaved into both the thermostat system and the lambda box. Ray