MFI self build pump setup and tuning

[BartdeBruijn]

Hi!
After finishing the full restoration of my ‘69 911T she is performing beautifuly ! Now a few years later I decided to build a more powerful engine and keep the matching number engine as it is.
Slowly I am collecting parts for this new engine. It should run with this fantastic MFI. I have restored the whole MFI setup. Bored throttle bodies removing the wear and added one size bigger valves. After that I restored the whole MFI pump, great piece of mechanical engineering.
With a lot of information from the forum
Jonny042 - Project heavy metal
Jeffc280sl - Open heart surgery
356RS [Mark Jung]
And many others!
I managed to restore the pump and build my calibration setup. Bringing it to Eisenbrand Renn & Motorsport is easy but only half the fun, right!?

So that as a short introduction, I ran into some issues that I do not really know how to resolve.
1)
In picture one [Bosch datasheet], rack movement at pre adjustment, I managed to get the following vallues for the rack.
Angle rpm rack
Max - 2000 - 7.02 (should be 7.00)
0 - 400 - 4.46 (should be 4.45)
8.3 - 800 - 4.25 (should be 4.25)
29.5 - 2000 - 4.73 (should be 4.75)

Now when I move forward to the next set of tests the Full load vallues,
Angle rpm rack
Max - 700 - 7.00 (should be 6.25)
Max - 900 - 6.83 (should be 6.75)
Max - 2000 - 7.01 (should be 7.00)
Max - 3000 - - - - (should be 7.3)

The full load vallues should be corrected via the rack head screw[as per Bosch data sheet], right?
Question 1: If so, I will alter also the value(s) obtained in the first table as the first line adjustment is through the rack head screw and that is the one I have to use to correct the second table. So feels like chasing my tail!

For now I am using a diesel calibration fluid that is odorless and not flammable (like petrol or white spirit) Only thing is that diesel (like) fluids have a slight higher viscosity.
Question 2: Does anyone has an idea on the effect of this difference on the quantities I am measuring/adjusting now?

Thanks a lot,
Bart

[stephers]

Impressive set up well done wish that I could help you but will be watching this thread

Thanks, Rick

[Jonny042]

That is a really nice setup! The inverter/variable speed drive is the same one I used on mine. I'm pleased to see another DIYer taking the initiative to build a test setup.

To answer your first question about the adjustment I would move on to the next tests and start playing with the other adjustments, since the part load settings are off they will need to be set with the part load screws. Ignore the "RACK" note in the book. Yes it will affect those adjustments too but you'll have to fiddle with the part load settings to get it dialled. By the looks of it you are not far off.

The calibration fluid viscosity should not affect the tests appreciably. The pump is a positive displacement device and will deliver the same amount of fuel (or fluid) regardless the viscosity (within reason of course).

Last but not least, I notice you haven't replaced the thermostat with a "test" screw (that I can see) but you must have done something to accomplish this or you would be getting fuel delivery far in excess of the specifications.

Enjoy!

[BartdeBruijn]

Hereby video of working test setup!

https://youtu.be/o7XkqSn0jDk

[Jonny042]

Hereby video of working test setup!

https://youtu.be/o7XkqSn0jDk

I like the way you used the fuel cut-off solenoid to stop delivery before the test. If I had to build another test bench I'd look into using a much smaller electric motor and drive setup, I went with a fairly big motor so I could accelerate to the test speed in a short time.

[edmayo]

That's an impressive set up for what may be a one time use? I can't tell, is there oil in the pump sump? don't see any evidence of oil in the clear return tube.