Hey Paul,

I am getting my Johnson charge cooled 40hp rotary ready. I need some
recommendation for parts for building a PSRU. I really do not want to
use a belt reduction unit, I was thinking of a planetary reduction
unit if I can make one light enough. I have a machine shop both
manual and cnc mills and lathes.

I am trying to keep this small rotary as light as possible and with
your knowledge and experience you are the man to talk to.

David Mikesell


Our latest design can be scaled down if you can find a smaller
planetary.

Your best bet is find an auto transmission repair shop  and ask to
see his saved parts collection. Look for a Jatco transmission from an
older rear drive Japanese car. It is a scaled down Ford TX. The rear
planet carrier is what you want. The mechanic will know what you are
talking about. You need the corresponding sun and ring gears.

Paul Lamar



I am limited to 4000 maybe 4500 (if I can cool it enough) rpms. What
is the ratio of this planetary gear set? I think I found the gears
out of a Nissan 3LN/4LN transmission, 30 tooth sun and 39 tooth
planet gears. Does this sound right to you Paul?

David Mikesell

Take some pictures of the gears. The ratio is ring over sun plus
one.

Paul Lamar


Hey Paul,

Do you think using a intercooler on the charge cooled rotary would
help with it running cooler and developing more power? I am also
thinking of making some new end plates to allow the ends to be water
cooled.

David Mikesell

Apples and Oranges. Intercooler cool the air going into the engine
to prevent pre ignition or detonation. This can fracture a stock iron
apex seal. The Iannetti silicon nitride seals appear to be immune to this
however pre ignition is still a bad thing. That means the mixture starts
expanding well before the rotor gets to best place for it and the
engine wants to back up :-) Any time you compress air it gets hotter.
If it gets hot enough with the right amount of fuel in it ..it will
explode.

The turbo charger compresses air and makes it hotter. That is why
intercoolers are used. The combustion air going into the engine needs
to be below about 150 F.

This has next to nothing to do with engine cooling. Engine cooling cools
the metal the engine is made from keeping it from melting.

Paul Lamar

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