Author Topic: PD series Petter engines, 3-1/2" bore and 4-1/3" stroke anybody seen one?  (Read 5830 times)


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  PD series  Petter engines air cooled, with 3-1/2" bore and 4-1/3" stroke. Anybody seen one?
  When looking through the Petter specs. Many share the common 4-1/3" stroke. Noting that the PH use a 3-7/16 bore and the PJ has a much larger 3-13/16 bore. With the PD being a little larger than the PH with 3-1/2".
  The line of thinking is.........When in there anyways and boring. The PH sleeve while being thick walled won't take a 3-13/16" bore up from the 3-7/16". There is however plenty of sleeve wall thickness left if bored 3-1/2" and a PD piston used.
  Any ideas if the PD engines shared the same piston pin and deck height as the AV,PH & PJ engines? Odds are they do as commonality reduces production costs.
  I wish I could have found a PJ1W engine but the PH1W is all I have to work with. The generator project leaves the factory PH1W a couple of HP short. I'm hoping a little tuning and mild tinkering by cleaning up the ports and a little more displacement. This engine would be able to make 10+HP at 1800rpm without excessive smoke.
  Of interest the PD engine with the 3-1/2" bore makes as much power as the PJ engines with the 3-13/16" bore? The PD is only 1/8" more bore than the 8HP PH series?
  Did the PD engines have better flowing cylinder heads or where did the extra HP come from?     


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Re: PD series Petter engines, 3-1/2" bore and 4-1/3" stroke anybody seen one?
« Reply #1 on: December 01, 2009, 11:30:44 PM »
Without seeing the specs on the PD my first thougt is the PD might be rated at 1800 rpm VS the 1500 of the PH
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There's the big PDV, but they don't appear to have made a small single or twin cylinder version in that bore/stroke range.

That's got larger bore & stroke though.

There were a few PD's made, but 1956 or so, and not an engine that seems to crop up much at all these days.