What's the limiting factor on squeezing more fuel flow out of CIS systems? - Page 2

RarlyL8 · RarlyL8's Garage

It seems reasonable that the only way you're going to get a perfect AFR curve out of CIS is to attach the changes in active control pressure to a targeted AFR reading. Adjustable cockpit knobs on the fly are not going to accomplish that goal in a practical way. Hell I can't even keep my eyes on the boost gage when the hammer is down. You're going to need something active automatic and adaptable. I guess that is what the electronic WUR guys are trying to do. At some point it's like putting a laser site on a sawed off shotgun.

heliolps2 · heliolps2's Garage

I would not be looking for on the automatic adjustment ,or adjustment on the fly, which can be done , I think it would be great when I'm on the track for 30 to 40 minutes at time.....on a race weekend, but the point being is by controlling the voltage to control our WCP value with a knob is a much easier than having to stopping the car and adjusting the WUR, and the GREAT part is the would no modification needed to our WUR's . Much like people suggest using vacuum restrictor on the vacuum side of the WUR to control the onset boost , so that WUR doesn't go to full rich at a lower RPM, I really think this would work,

PcarPhil · 09-18-2014, 06:43 AM

There's a guy over in the 911 tech forum that mounted a fuel pressure regulator between his seats and he uses that to adjust system pressure on the fly. While that's a more in depth install the results are probably more controllable/instantaneous too. I'm trying to find the post now.

Just another option...

PcarPhil · 07:19 AM

Here it is - don gilbert is the Pelican with this setup:
CIS Experts - Are these WUR re-calibration steps correct?

first pic is my reg. next few are of dailing in afr instanly. afr gage on top control press on the bottom. car come alive on the dyno at 49lbs of warm press (217 rwhp and counting) this cannot be achieved with the factory wur setting. They make a electronic one, but very expensive and lots of fiddling. this settup cost around 100 bucks and gives real flexibility on the afr. i can dail in for milage (28+ at 58 lbs) or performance.

Speedy Squirrel · Speedy Squirrel's Garage

Yes! Let's all run 75psi of gasoline into the passenger compartment. What could go wrong?

PcarPhil · 09-18-2014, 07:30 AM

Quote:

Originally Posted by Speedy Squirrel

Yes! Let's all run 75psi of gasoline into the passenger compartment. What could go wrong?

Mount it to the engine side of the firewall, and just have the knob inside the cabin?!

heliolps2 · heliolps2's Garage

Great Idea ! love it

WinRice · 09-18-2014, 01:08 PM

Here's a good thread on how far the factory went with a 934. Notice the lack of a WUR, and the addition of a simple pressure regulator. It had to be tuned for each day.

Information about the 934 CIS Injection

Let's face it, the CIS system is just a fluid valve system and could be 're-engineered' for 1000 HP or more, depending on how extreme you wanted to 're-engineer'....

WinRice · 01:12 PM

Quote:

Originally Posted by speedy squirrel

yes! Let's all run 75psi of gasoline into the passenger compartment. What could go wrong?

lmao

Of course, you do have about half that running through the tunnel fuel line.

RarlyL8 · RarlyL8's Garage

For you horsepower junkies here is a picture of something we are working on right now. On the right is a 930 barrel showing the metering slits. On the left is a 934 barrel showing the metering slits. The slits on the 934 are over twice as wide as those of the 930. We plan to modify the 930 slits to 934 spec then pull that sizing down as needed for street manners.

JFairman · 09-18-2014, 06:20 PM

Tapered metering slits that get wider toward the top might work if done right. Is Larry at CIS Flowtech doing this metering slit modification?

RarlyL8 · RarlyL8's Garage

Larry and I are working on it together. My friends in the aerospace industry have equipment with the accuracy needed to do the job correctly. The 930 slit is the width of a human hair. This mod is intended for use in race cars but juuuust might find it's way to the street on a well built engine.

Edelweiss · 09-19-2014, 03:35 AM

We have done this already - with the help of a German university, what we found out is that the slits are just a part of the story and it was the simple one, later it gets a little more complicated.

However you are right - CIS can do much more: on a 8,5 : 1, 3,4 L 934 we see 720 hp using a modern cam profile..

And still it is not running lean - so the limit is not CIS !

Best reg.

Dirk

RarlyL8 · RarlyL8's Garage

Very good; Modern electronics aside, I cannot imagine after 30+ years that there is much left that has not been modified by someone.

jsveb · jsveb's Garage

Is it within the boundaries Of this thread for you guys, Brian, and Jim etc., to explain how the barrels, be it 930 or 934, work?

The pictures Brian supplied would serve an explanation well.

quattrorunner · quattrorunner's Garage

I'm actually suprised that after 35 years were still trying reverse engineer this. Those guys were super smart. Or technology changed and most engineers dont look at that direction when thinking of car fueling. Either way the Bosch system in pretty cool.

Edelweiss · 09-19-2014, 07:31 AM

Quote:

Originally Posted by quattrorunner

I'm actually suprised that after 35 years were still trying reverse engineer this. Those guys were super smart. Or technology changed and most engineers dont look at that direction when thinking of car fueling. Either way the Bosch system in pretty cool.

Yes 100 % right - it is such a beautyful peace of engineering !

Just love it....

jsveb · jsveb's Garage

I think the reason why we can still improve upon CIS is because it is a system within systems. Earlier on there were probably other limiting factors; maybe the turbocharger couldn't keep up or the charge became too hot causing detonation or burned valves etc. my point is bits and pieces within this sustem are affected by new technology allowing for constant improvement of an otherwise well engineered entity.
Makes sense...?

Edelweiss · 09-19-2014, 07:56 AM

Quote:

Originally Posted by jsveb

I think the reason why we can still improve upon CIS is because it is a system within systems. Earlier on there were probably other limiting factors; maybe the turbocharger couldn't keep up or the charge became too hot causing detonation or burned valves etc. my point is bits and pieces within this sustem are affected by new technology allowing for constant improvement of an otherwise well engineered entity.
Makes sense...?

Yes - so right, we where working on this system for a long time now starting with Golf 1 1,6 and 1,8 then Golf 2 / 16 V Group A race cars. Playing around with the first 930 we got our hands on a complete 934 CIS system and wow this time put it on the car generating 580 to 620 hp the lambda curve was as perfect as I could be - absolutely flat 0,84 through the whole rpm on full load.

There we knew it is all about understanding the complexity and cooperation of the single Bosch components - then CIS is a pleasure to work with.

Producing the high end fuel heads is quite a task and expensive so it is for puristic freaks and race application where you are forced to use the homologated technology.

Best reg.

Dirk

RarlyL8 · RarlyL8's Garage

The things we do (we meaning myself and the folks I work with) to "improve" CIS involve tweaking what exists to work outside the factory specs on engines that perform outside factory specs. The machine work that will be done to the 930 metering slits will mimic those of the 934. Things like that are just an expansion on the platform. Any modern EFI is more efficient than archaic mechanical fuel injection but MFI/CIS still has a place with the old school guys.
Jim W and I put together some information specific to 930 CIS and posted it on the CIS Primer on my website. We plan to add a lot more and include the power mods as well.