CIS Flow mods, who can help/enlighten

[awjens]

First of all if your here to post to tell me it can't be done, don't waste your breath. I am not so full of myself that I don't believe there may be a remote possibility that we can't do it. However if you are here to help/share knowledge so that everyone on this board can benefit, please do help and post constructive criticism. I have spent my career doing things that were never done before, many times after being told it wasn't possible.

I'm asking people to please be polite, respectful and help me help everyone on this board that has come to this crossroad only to be told its too expensive or not possible.

I'm looking for a couple metering spools besides the one i have. The first thing we are going to try and do is make our own spool. That requires skilled journeymen machinists which I am not. But I do know where to find them. I do not have any 930 spools so if anyone has one they can donate for the purpose of blueprinting it, we wont modify it unless you ask.

I will be taking this metering valve to the lab and looking at it under the scope. I will measure the profile and see if its possible for us to machine it. We can grind a new electrode and re-machine the slots on one of our turbine blade machines. I may scrap a spool or two so if anyone has any they want to sacrifice in an attempt to learn something for everyone, that's what will happen. I have no interest in keeping secrets. My interest is to find out how this thing works and report back. I want a CIS head to flow 400 HP and maintain idle characteristics up to mid range. If I can do that the sky may be the limit on modifying these heads. Using a modified fuel head and Reanimotions Digital WUR I think this can work for a lot of cars.

This machine is not the backyard machine. So obviously this isn't something that anyone can do. Maybe we cannot. However given 32 years in the marketplace producing extremely high accuracy EDM machines for the Jet and Land based turbine industry as well as the fuel injector market I do believe its possible. It may be machined from scratch (metering spool) and then burned. Pictures of it I have seen lead me to believe that may be possible.

When I read posts about modifications made by working with Universities in Germany I believe this can be done with one of these machines.

We currently have machines that use round tungsten electrodes with a .010 diameter and a hole in the center of them for water to flow thru. We don't buy these machines, we design/build them. For all the nay-sayers this is old technology. These electrodes can burn thru almost any alloy known to man. We can move the part in slow increments to create shaped holes with this machine. The result is hundreds of cooling holes blasted in hundreds of blades and veins, all flow tested. The highest grade of components for commercial and Military jet engines. Certainly more accurate than a CIS metering spool. We can grind/shape electrodes to make a one cut pass. If Bosch did it 35 years ago, the right guy with the right machine can do it now.

If anyone on here has more information they would like to share please speak out. I will admit I'm new to how this head works, but I think its time for the "black magic" of CIS to be exposed.

The simple goal is to be able to modify something and keep relative stock appearance for the older turbos and the engines with aftermarket turbos and superchargers as well as the robust CIS injection. Its almost bulletproof. If all a guy has to do is modify a fuel head and and a digital WUR to get 500-700 HP of fuel thru these heads EFI is much less desirable for many.

I am an Electrical Engineer so going full EFI is not something I am afraid of. Tuning is something I am learning with the help of others.

Below is a picture of an airbox, made by the machinists at the shop. It has been detailed and built on a fixture, not with clamps and visegrips. Everything done here is precision and repeatable.

[kenikh]

Any pics of what a metering spool looks like, where it can be found, etc? Most of us haven't been deep into the guts of our CIS systems, so any pointers would likely help get the ball rolling.

[Alan L]

I'm guessing he is referring to the fuel head metering slits?
Basically the fuel head consists of the balance/flow chambers and the individual slits fed by those.
I'm guessing he is talking of modifying the slits? as per Imagine FDs.
Alan

[LeftCoastErik]

subscribed and fascinated

[Speedy Squirrel]

For starters, buy this book:

http://www.amazon.com/Automotive-electric-electronic-systems-Robert/dp/3184191109

It covers a lot of CIS principles in detail. Don't buy a newer edition, all of the CIS stuff is left out (ancient history).

Bosch made their own electronic CIS in the mid - '80's:



Notice that they have added a potentiometer to give airflow feedback. This allows the CP adjustment to be coupled to the air meter position.

Rather than burn through a bunch of barrels (they are fitted by class to specific head bore diameters BTW), you should get an engineer to calculate the flow produced by different slit widths. I think you have all the data required. I fear you will burn through a lot of barrels otherwise.

[kenikh]

Bought the cheapest copy of that edition available. Looks good!

[Alan L]

Originally Posted by Speedy Squirrel

For starters, buy this book:

http://www.amazon.com/Automotive-electric-electronic-systems-Robert/dp/3184191109

It covers a lot of CIS principles in detail. Don't buy a newer edition, all of the CIS stuff is left out (ancient history).

Bosch made their own electronic CIS in the mid - '80's:



Notice that they have added a potentiometer to give airflow feedback. This allows the CP adjustment to be coupled to the air meter position.

Rather than burn through a bunch of barrels (they are fitted by class to specific head bore diameters BTW), you should get an engineer to calculate the flow produced by different slit widths. I think you have all the data required. I fear you will burn through a lot of barrels otherwise.

What vehicles were these fitted to? Not the 930?
Regards
Alan

[kenikh]

Mercedes mostly. Merc V8 is a great option for a 930 BTW.

[awjens]

I will locate the book. I may already have the earlier edition as i purchased it in the mid 90's. We have a fluid engineer and as luck would have it, he is a car enthusiast. All of this is good information. I am really looking for a 0 438 100 031 right now to compare with the 0 438 100 097. We are going to look at both of these heads. Even a head for a larger displacement V8 from Mercedes. We want to understand all aspects of the upper and lower chambers and their volumes with relationship to the size of the metering slits. if there is anyone in Michigan that has experience with rebuilding these heads please chime in.

[Tippy]

I will tell you this, why the hell are you the 1st person actually wanting to do this? I've been pondering this since day 1 on the limitations of CIS questioning why hasn't anyone made one flow up to 1000hp, or 1500hp, while improving known weak areas?

I used to be an F15 engine mechanic and rebuilt 1000's of them. I know the blades and their cooling holes quite well.

[RarlyL8]

I have a fairly thorough CIS Primer on our home page that is free for all to use. Go to Porche Enthusiasts Page and you will see it. Jim Williams put this together years ago for the N/A systems, I consulted on the turbo versions.

Larry Fletcher and I worked on metering slit modification a couple of years ago in an effort to reproduce the 934 metering valve. The machine used was EDM, the tolerance needed is 0.001". The resulting piece will support 700HP. I don't know what you could get out of a 911 fuel distributor as our starting point was double the capabilities of the -097 FD.

You can see in this photo the metering slits on the modified version are twice that of the stock 930.

[Tippy]

Did you mean 0.0001" tolerance?

[JFairman]

Tapered metering slits that are stock width at the bottom and get wider towards the top might work well too.

[awjens]

There's no way the tolerance is .0001 inches. That's not achievable with any EDM machine nor is it necessary. The blades, veins and injectors in every vehicle on the road and jet in the sky are not manufactured to that tolerance. Its simply a slot, with exacting flows. EDM is very precise and overburn is very controllable and repeatable. The small amount of flow differences in a EDM produced slot would easily be adjusted on the flow head. I would venture to say the the remaining variables in these engines, compression, flow of intake runners, airbox construction, cylinder leakage etc etc etc would easily outweigh any machined differences in this EDM produced slot. It simply wont show up in any liquid flow test. It is that precise. After running my engine on a dyno and recording AFR's on each cylinder and EGT's on each cylinder it appears the only way to make this this best it can be is adjusting the head under full load at full boost. Over and over again. Different RPM, different Air temps, adjustable boost all contributed to different EGT's. Then map it. That wont be possible with CIS. We have to target a flow and AFR that keeps all 6 cylinders happy at best. We have all been running these engines boosted and NA without really knowing whats going on in each cylinder. At best an AFR gauge in each pipe. I would say if we can increase the flow then it will be exact enough by the methods everyone is currently using. A 3-5 minute test capturing fuel from every injector and weighing it on a gram scale. Lifting the sensor plate different amounts and recording weights. It shouldn't matter if we lift it, lower it, during a test as long as the result is 3% across the board on all six injectors. I have done this at least 100 times, all with the same result, 2-3% with the injectors installed. The only test I have not done it to place the injectors in a pressurized environment to see how it affects flow under boost. This would be a static test so not so definitive, but it may shed a bit of light in the affects of boost. The engineers I spoke to that design fuel injectors say a higher pressure opening injector reduces the affect of boost. I don't think this is possible with CIS.

[awjens]

Originally Posted by JFairman

Tapered metering slits that are stock width at the bottom and get wider towards the top might work well too.

That's what we are trying to produce. Trying to maintain idle characteristics yet give us a point where we can make it fat. If the Digital WUR is working we may be able to produce an area in the slot that the metering valve moves to only under heavy boost. Its the secondary chamber volumes and the springs (possibly) that also affect flow. I will leave that for the fluid engineer. Somebody has got to be able to sort this out. We don't want to burn anything until we are convinced what the target is. We know we can change the slot. What we don't know is how much to change it and how it affects the other components in the head. Where is that German guy that designed this today..... He could surely save us some time.

[awjens]

Originally Posted by Tippy

I will tell you this, why the hell are you the 1st person actually wanting to do this? I've been pondering this since day 1 on the limitations of CIS questioning why hasn't anyone made one flow up to 1000hp, or 1500hp, while improving known weak areas?

I used to be an F15 engine mechanic and rebuilt 1000's of them. I know the blades and their cooling holes quite well.

I'm certainly not the first person, I may be a bit more determined and open to share any results that we come up with. Secrets on something this old is just absurd. Given the complexity of something able to burn these slots is why its not commonly done. We make a small machine that fits on a desk. It burns injector nozzles. Has a mechanical indexer, rotates the injector and the the EDM burns the hole. One of these machines can probably do the job with a larger EDM generator. Once tooled up relatively easy to produce. Locate the first slot, burn and index. We will shortly know how accurate the original slots are. (Positional accuracy of the slot in relation to the rest of the spool). Our guess is that during this time a mechanical rotation device was used. These were easily accurate to .001 inches. Rested on a mechanical hard stop ant each index point. 6 slots at 60 degree intervals. My job was easy, sequence the device. The skill was the journeyman machinists that built these indexers. A trade that is sadly shrinking. My idea was to find some old scrapper parts, locate a 60 degree indexer, and boom... we are modifying things. A machinist makes the electrode, puts it in a collet, picks up the first slot, and I press a button. 60 minutes later its done. All for the rock bottom price to pelicans of $10,000.000.00 per spool. Quantity discounts available. Tell all your friends.....

[Alan L]

Originally Posted by awjens

That's what we are trying to produce. Trying to maintain idle characteristics yet give us a point where we can make it fat. If the Digital WUR is working we may be able to produce an area in the slot that the metering valve moves to only under heavy boost. Its the secondary chamber volumes and the springs (possibly) that also affect flow. I will leave that for the fluid engineer. Somebody has got to be able to sort this out. We don't want to burn anything until we are convinced what the target is. We know we can change the slot. What we don't know is how much to change it and how it affects the other components in the head. Where is that German guy that designed this today..... He could surely save us some time.

Hasn't this already been done - tapered slits - Imagine FD?
Alan

[JFairman]

Originally Posted by Alan L

Hasn't this already been done - tapered slits - Imagine FD?
Alan

The Imagine Auto modified fuel heads from 8 years ago were rebuilt and modified by Larry Fletcher of CIS Flowtech CIS Flowtech - Rebuilding Bosch Fuel Distributors & Warm-Up Regulators
Larry's a good guy and he does nice work.

The default ones flowed ~20% more fuel than stock and you can trim that with an adjustable control pressure regulator if it's too rich during cruise and boost but then the air flow sensor plate is a little higher in it's venturi cone than with a stock fuel head restricting intake air flow during boost.
I have one, it works well, and I don't think the metering slits were tapered. I don't think thats been done yet.

[gavinc69]

This is great stuff. Looks like I left the party too early, but I wanted to get my car up and running asap.

[LOWFAT]

I'm watching this. I like the old cis system and anyone who will help keep it alive is alright with me. Yes I know there is much to be gained by going efi but with my simplified system if anything goes wrong on the road I can diagnose the problem and fix it right there and be back on my way.