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On 27 Oct 99, at 7:58, Kooser, Jake wrote:
> Since we're on the
> subject, does anyone know if there are limitations to the size of maximum
> oil pump that can be used in a FF system without interfering with the rear
> engine mounting bar?
I know that you can replace the 21mm pump with a 25, but it is
close, so I don't think a 30 would fit. It is likely that you could
replace the 26 with a 30 (with the dished cam.)
Also, I think I read somewhere - maybe in an article
> in the "every Hot VW that's not a type III" magazine that some racers use a
> stock oil pump even in big drag race engines because the extra capacity Vs.
> load on the engine ratio wasn't very good. Any ideas on this theory?
I think this makes very good sense. There's no support for the "If
some is good then more is better!" also known as the Sophomore
Theory.
While oiling WAS a problem, there were few oiling problems after
67, when the cross-drilled cranks were introduced, or 70, when the
dual pressure relief cases were introduced. Still VW went to 26mm
in 72.
My feeling is that, since pump output is proportional to rpm, oiling
is most likely to be a problem at idle, when the pressure clearly
drops. Drag and race cars are probably just concerned with loss of
oil pressure on acceleration and turns, hence we often see these
cars with larger sumps. This makes sense, but wasting power on
pumping extra oil that just gets dumped by the pressure relief
valves does not.
Jim
-
Jim Adney jadney@vwtype3.org
Madison WI USA
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