Very cool picture of a Viper oil pump with the inner gear neatly expanded
into the outer gear


Read the thread here...
http://forums.viperclub.org/threads/667258-SRT10-Oil-Pump-Failure-%28Gen-3%29-w-PhotosAnd the Nissan thread linked in the above...
http://www.skylife4ever.com/2011/01/real-problem-with-rb26-oil-pump.htmlDue to not paying attention in class, I previously just took it for granted that the
inner gear was driven by some kind of lug that fitted in the space between the two
lugs/dogs

I now realise that the lugs are the drive surfaces that sit on the
flats either side of the crankshaft nose. From an engineering point of view, this is
even worse in terms of generating bursting stresses.
Anyone who has used a Cresent spanner to try and undo a rusted hex nut will know
how easy it is round off the corners. That same mechanism allows the flats on the
crankshaft to generate radial forces in the gear.
Looking at the later version Toyota inner gear, changing from 11 teeth to 10 teeth
allows the drive lugs to be better located, and for sure the rounded tooth shape will
pretty much eliminate stress risers on the outer surface. However, looking at the
other examples of similar rotor designs, it seems that the cutaway between the
drive lugs is now the likely point of origin.
Porting the outlet is an interesting question, as if the oil cannot exit the pumping
chamber quicly enough, the exit port becomes a restriction, and the pressure inside
the pump will be higher due to that restriction. So it would be interesting to tap a
pressure gauge into the the pumping chamber and see if porting actually reduces
the chamber pressure.
Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.