4 Attachment(s)
Question on MFI tuning on own build MFI test bench
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