[QUOTE=awjens;9102622] It was rotating, as you suggest, in the bore. So the chipped edge moved from cylinder to cylinder. I was trying to balance flows. And it was extremely frustrating to see the inconsistencies. But what got worse was they moved from cylinder to cylinder. I finally pulled the fuel head down. Several times in fact. Until I noticed the chip on the metering edge on the piston (the lower edge of the waist). I had those dimensions to work with, so spun one up in the lathe and finished it by polishing til clearance fit (just). I am sure I was Micing it, but can't remember exactly. The piston is hardened steel (like tool steel). So I then sent mine off for hardening. Which changed the dimensions again and some hours more polishing. I am guessing a piece of grit in the fuel head at some time previous. Don't know. The car came with a rats nest of issues like that. But having had to delve that far into the fuel head I came away blown away by what they managed to achieve. Hard to think you could design and fabricate something like that and believe it would work - and whats more - for 1000's of miles like you say. I guess some pistons will fit and others will be too tight if you interchange. Which is why they are paired items. Bosch must have had a large box of misfit pistons and metering cylinders at some point.
Good luck on your quest - lots of CIS addicts following this.
But I think Brians comments re -market for high HP SC type heads commercially would be limited.
Regards
Alan

100-027
outlet orifice diameter approximately 0.85mm
metering slit length 6.0 mm
metering slit width 0.100 mm

The 928 head correct? Do you know the flow in cc/min per cylinder?

Remember, more fuel flow means a higher control pressure is allowed, therefore less travel of the air plate for any given mixture point.

There were only ever 6 different air plate sizes, the cone addition on the 934/5 and the dome on the later CIS-E Mercedes V8s is the only change to those stock sizes I've ever seen.

Yes the 928 head, unfortunately I've not yet managed to measure the flow from these units

Ha! Fookin' hilarious right thar!:D

Butt to answer your question, I know of several, four-legged forum members (:eek:) that could tell you the exact time, any time!!!

Anyone have a boosted SC or a 911/930 turbo in Michigan willing to stick a camera in the car to watch the air sensor plate travel? Even a stock SC that they aren't afraid to wind up to redline?

I am curious how far the sensor plate/piston travels. My engine is on the stand and it rev's so quick with no load I can't see much....

While these fuel heads are impressive they are nothing compared to a Bosch VE diesel rotary injection pump in terms of mechanical marvel. The VE plunger not only develops the injection pressure (1150 bar) but also rotates at the same time to distribute the fuel to each injector. The plunger and the bore in the pressure head that it operates in are fitted with no seals or piston rings, just a high tolerance fit while allowing the plunger to both pump and rotate. The pump also controls injection timing based on engine temp, meters the correct amount of fuel based on throttle position and boost psi and governs maximum engine speed. They are an unbelievable mechanical device.

The mechanical fuel injection pumps on 1969-1973 911s, which preceded CIS, are marvels. Full sequential fuel injection at near DFI pressures in the 1960s.

Yes, I agree. Space cams!

Don't get off topic. This is a CIS thread, folks.

Let's really try keep it that way. ;)

Hoping to have some more parts today or tomorrow to measure. I have to say every day I am learning something. We are making a device to hold the spool so we can capture flow rates without it being in a head. The detail drawing of the SC spool is almost done. Then its off to MFG. We are going to do all the work here with the exception of the finish bore on the i.d. Luckily the Motor city has lots of places that can duplicate this fit and finish. It will be matched to the piston from that head.

The wire EDM program is done, so its ready to make diaphragms if we need to. I will probably make 10 or so, as well as order all the orings for these heads so we no longer need to order rebuild kits.

Still looking for more heads from anything....

Once you get the head done you will need to address the flow in the intake/intercooler, etc. I suggest EGTs on each header bank and then figure out how you are going to even the flow. The intake will flow inconstantly on the outer runners. If you are running a single 02 you are going to show that you are safe once you get to where you want to go...the reality is you are still leaning out cylinders and will break a ring or burn a hole. You will be running a cumulative AFR.

FWIW we did all this many years ago and supported the HP we wanted. Larry still does it and if you called him and said here are my AFRs and here is what I need he would build it. Larry is one of the best people I have ever known. That said the reason we started doing EFI is the cost of tooling up and covering every component that needed to be modified was far greater than then swapping to EFI. Not to mention driveablity and fuel economy was far better. I could lean an injector back at cruise (good injectors) and get 28MPG. In the end it was cheaper and when you wanted to add a new turbo or modify the car again it was a few hours on the dyno tuning.

Since the market has gone nuts (still Baffles me) few are touching these cars. In fact I have one in the garage right now the guy wants back to stock. From a business standpoint makes little to sense compared to 10 years ago.

What is your target for fuel mass flowrate and how did you come up with it? In other words, what is your HP objective?

400-450 hp, Boosted AFR 11.7 to 12.0.

I have a set of test pipes with 8 wideband o2's and gauges. Also 6 egt's adaptors for air pump holes. I ran this setup before with 2 injectors upstream of the airbox. It worked until on day.... backfire and end of the airbox. New design airbox with blow off valve. I don't want fuel in the airbox.

400-450 hp, Boosted AFR 11.7 to 12.0.

So I assume this is not a stock 3.0 with stock pistons? You'll need about 1 bar boost into 3L. Probably over 4 lbs/min of fuel.

You can do 1 BAR with 8.5, twin plugs and dead nuts tuning and/or knock control. SC cams wouldn't be the best choice...993SS or Evo. Nonetheless, doable even on CIS.

I thought they were 9.3 CR? I guess it depends on the year.

Depends. Usually 8.5. My SC has 9.8 Euros, but there were also 9.3 Euros. They went as high as 10.3 in euro spec.