Pelican Parts Forums - Let's discuss digital WURs and replacing K-Jet Lambda

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- - Let's discuss digital WURs and replacing K-Jet Lambda (http://forums.pelicanparts.com/porsche-911-technical-forum/997787-lets-discuss-digital-wurs-replacing-k-jet-lambda.html)

Quote:

Originally Posted by tirwin (Post 10053539)

You still need the block which Dkubus sells for $300-400 US. Still spendy for a CNC’d chunk of aluminum. They need to recover their R&D costs, but still... This is not rocket surgery.

Not required for CIS-Lambda, so save yourself some money here if you have a Frequency Valve in your system

Steve,

Thanks for jumping in.

I thought I was sending an email to you and an email to Dkubus. Somehow I ended up sending two emails to Dkubus - one to ‘info’ and the other to ‘sales’. Sorry. I was trying to get to you.

That’s excellent background info. Very helpful. And it appears you’ve done a lot of good work.

As these CIS cars are getting older, I think options are good. I was just stunned at the price quote I received from Dkubus. That’s a non-starter to me. Maybe I am missing something.

If a block isn’t required for CIS lamba, where does the injector that adjusts control pressure mount?

with CIS-Lambda there is no actual need for control pressure adjustment, the Bosch WUR is sufficient for initial warm up and basic control pressure maintenance.
All of the actual system tuning can be done using just the Frequency Valve and FrankenCIS

The frequency valve as greater range, accuracy and responsiveness than the control pressure circuit can provide

I was fascinated by this thread,,,very educational..but for us non techie folks..what is the WUR replacement option for NON Lamba vehicles (83 SC)?

Thanks Tirwin for this thread. You and others have answered most of the questions that were in the back of my mind.
My 81 SC Turbo conversion works pretty well with CIS and BL Wur so no strong motivation to change.
Everyone seems to blame the WUR for all of their problems. Would any of these systems work better as long as you are using the fuel head and injectors that came on the car?
My opinion at the moment is to stick with what I have and if I want a complex expensive project in the future I will go with EFI and COP just because it's cool.
:D

Quote:

Originally Posted by tirwin (Post 10053535)

My opinion for what it’s worth... EFI is a slippery slope for a CIS car. I have looked at this a lot.

You can take a very mild approach and do something like Bitz or Rasant. They are basically bolt-ons. Let’s say you were faced with spending a bunch of money on CIS. Maybe you had a bastardized motor with the wrong CIS parts or were missing parts. That’s a clear case where the cost to retain CIS isn’t worth it and EFI makes a lot of sense.

But if the reason you want EFI is to hotrod the motor, you’re really talking about a lot of money. Intake, cams, pistons, ignition and fuel delivery probably needs to change. Machine shop work. My napkin math says it’s the cost of a rebuild plus another $7-8k. Now if you were at the point of needing to do a rebuild anyway, maybe it’s not so bad. Then it’s just the incremental cost.

It might be cheaper to just get another one that already has Motronic. :D

Yes, the steepness of the slope - and how slick it can be - can be a real problem, especially if a bunch of things just seem to make sense to do at the same time...

You don't have to go all-out; some people can resist "while you're in there". A lot of folks had good success with simply adding modern injectors to CIS manifolds - even for 930's, folks have made large HP numbers on the factory pancake just by ditching CIS. You might not get the absolute best results - depending on what you were going for - but merely ridding yourself of CIS injectors can be a big win.

Which I think is the Achilles Heel of FrankenCIS - as interesting as the approach is and props to the folks doing it - because it retains CIS and adds yet more stuff... Which seemed appealing once - but now I think "if you're already adding a bunch of sensors, harness, ECU - why not bolt on two fuel rails and an FPR so you can use real injectors - and junk a whole pile of obsolete things?"

(Sorry to you guys in Cali.)

Any modern injector has vastly superior fuel atomzation compared to a CIS injector - and just firing fuel when the motor wants it instead of acting like a lawn sprinkler 100% of the time? kind of a big thing. And that's before you get fancy with tricks CIS can't do, like sequential versus batch injection, injector pulse timing, load-based cylinder trims...

Once you're at that point, it's a small step to add ignition maps and drive COP - hotter/longer spark, no distributor, individual cylinder trim if you want.

To answer jjeffries's question; the difference between a CIS car and the same car converted to EFI should be night-and-day; sharper throttle response, more power with better fuel economy and cleaner running.

CIS has a certain olde-worlde charm. Like my 915 did. Everyone has their own criteria/preferences/bias/direction. So it's all a personal choice.

There's a chap on this (very old) thread http://forums.pelicanparts.com/porsche-911-technical-forum/10077-cis-efi-conversions.html that converted his SC to EFI using all factory EFI from an '85 Chevy 2.8 V6 - which apparently set him back $150 in parts from a boneyard...

You need to put time/skills/learning into that equation to make it work. Or buy a bolt-on kit from someone who already applied a bunch of that. Or have a shop do it. Something for everyone... :cool:

Excellent information, much appreciated. Any day when you learn something is a good day! Best regards to all, John