Kugelfischer MFI pump

[chris_seven]

Have just found and bought a Kugelfisher 6 cylinder MFI pump of a similar type to that fitted to the SC/RS.



It seems in basically good order and rotates freely although I am sure it will benefit from an overhaul.

There are two more available and if anyone is interested please send me a PM.

[Flieger]

I always wondered if these were better than the Bosch? Were they lighter? Or just more available at the time?

[chris_seven]

I think by the time the SCRS was produced the Bosch pump was out of production.

The SC RS used a High Butterfly with a KF pump.

[Flieger]

Would you please measure the weights of the pump, and a Bosch if you have one handy? I am just curious.

[Steve@Rennsport]

Originally Posted by Flieger

I always wondered if these were better than the Bosch? Were they lighter? Or just more available at the time?

OMG, no. The Bosch ones were FAR better, however NLA at that time.

Many 935's had them as well.

KF pumps had no space cams and simply metered fuel by throttle opening and RPM. Fine for WOT, but terrible for anything less.

[Flieger]

Originally Posted by Steve@Rennsport

OMG, no. The Bosch ones were FAR better, however NLA at that time.

Many 935's had them as well.

KF pumps had no space cams and simply meetered fuel by throttle opening and RPM. Fine for WOT, but terrible for anything less.

Wow, interesting. Thanks for the info.

[jcge]

In the Bosch EP/RLA - throttle position rotates the "space cam" and engine speed moves the "space cam" fore/aft.

In the Kugelfischer PL O - throttle position moves the "irregular cone" fore/aft, and engine speed rotates the irregular cone.

Seems to me that the "irregular cone" of the Kugelfischer PL O is analogous to a "space cam" of the Bosch EP/RLA, with the ordinates (engine speed and throttle position) simply reversed. (But I'm happy to stand corrected !!! The above detail is from the BMW 2002 Tii factory manual)


(Pump specs previously posted by VZ935)

Gus Pfister at Pacific Fuel Injection should be able to get you up an running...

Regards
John

[Flieger]

Steve said it was only throttle position and rpm and your diagrams support this.

Bosch pumps also had barometric compensating cells that would change the position of the stylus on the space cam, as well as a shut-off solenoid for overrun fuel saving, and a thermostatic compensator to change the amount of fuel delivered to a cold engine. Not to mention the '69 cold start solenoid.

[jcge]

Interview with Gus Pfister regarding the Kugelfischer pumps

PDF product manuals here


Kugelfischer "irregular cone" - it contains the fuel "map" (analogous to the Bosch EP/RLA "space cam")

[Flieger]

Yes, it has a space cam but only two inputs. The Bosch has throttle and speed plus pressure and temperature.

[jcge]

Max - the Kugelfischer also has thermo compensation and an LDA for turbo applications. I haven't included all sections of the manual in the images above - you can access it here

I do not have Steve's experience with these pumps so cannot directly compare the Bosch/Kugelfischer in terms of which is "better".

I would note that the Kugelfischer's irregular cone appears to have a greater surface area than the Bosch, so potentially greater "resolution" (if you recall the increase in thickness of the space cams between early and later Bosch pumps to achieve this end) .

I find it hard to to imagine Porsche opting for a "worse" solution for its 954/SCRS

John

[Flieger]

OK, I could not see the baro cell on the pictures.

The Bosch was used for 917 and 906/910/907 as well as an 8 cylinder version for 908 so if the Kugelfischer was available at that time then the Bosch must be as good or better since they certainly spared no expense in 1970-1973.

[MBruns]

I built a 3.0 slide engine last year with one of those pumps new, it is supposed to be the SCRS pump, built a mount and linkage etc.. I was very happy with the way it ran and dynoed, the customer was very pleased with the driveability.

Mike Bruns JBRacing.com

[VZ935]

Old thread but figured I would comment. Have owned/raced 935's with both the "red knob" Bosch pumps and the kugelfischer pumps. All great motors but I prefer the kugelfischer 935/80 motors . But really, either way...

Originally Posted by jcge

Max - the Kugelfischer also has thermo compensation and an LDA for turbo applications. I haven't included all sections of the manual in the images above - you can access it here

I do not have Steve's experience with these pumps so cannot directly compare the Bosch/Kugelfischer in terms of which is "better".

I would note that the Kugelfischer's irregular cone appears to have a greater surface area than the Bosch, so potentially greater "resolution" (if you recall the increase in thickness of the space cams between early and later Bosch pumps to achieve this end) .

I find it hard to to imagine Porsche opting for a "worse" solution for its 954/SCRS

John

[Geneulm]

I bet they used this system because it was available, proven (then in use by bmw and ford 6cyl Racing teams). Also it was easier to fit than the ubiquitous Lucas system which typically ran off a camshaft or distributor drive. I’ve got a k-fisch in the stash and a Lucas system on an old triumph gt6. It’s a step WAY down from the K-Fisch but sure saw much wider use over a much longer period of time.