Subject: Cheap turbo compound rotary
From: rotaryeng
Date: 7/1/2012, 1:38 AM
To: AAAA Put this in the To box 


 I just had a brilliant idea.

    Unbolt the DD15 turbo
    and blow down turbine and bolt it on a Mazda p-port 3 rotor of
  around 500  HP.

    If you can do that and show a legitimate .39 BSFC on the dyno the
 world   will beat a   path to your door.

    Paul Lamar

   I know you can come up with a quick and dirty turbo compound Paul.
  Don't quit on the idea.  Maybe this is it.

   Van

   I think so. It might not be perfect but it can be optimized after
  the principle is demonstrated.

   Paul Lamar

   Big truck junkyard. I can get a whole older engine for $5K. They
  sell removed parts too.

   Kevin Alderman

   The DD15 has only been around for 3 years or so.

   Paul Lamar

  Steve again

  How sensitive to exhaust back pressure are diesel engines?
  I wonder what order of restriction the Axial Power Turbine would
  introduce and how a rotary will respond? Obviously 13, 20B's have
  been happy with driving a turbo turbine but how do they compare with
  an axial power turbine?

  Steve Izett

  Well here is some old NACA data on the subject of back pressure on
  TC engines. Sorry about the crappy copy but what do you expect from
  government work? I tried to clean it up but it is tedious work.
  -----------------------------------------------------------------

  Here is the complete raw original paper.
  Somewhat easier to read the numbers.

  It looks like the net power continues to increase up to a back
  pressure of 60 inches of Hg.

  Paul Lamar

  Mazda used sequential turbines on both the later 13B and the 20B.
 The exchange of one for an axial flow should not change things by
 much. Still gas flows through. The 20B displacement calculated as
 per racing is 3.928L. use this and design RPM to get basic gas flow
 outside boost. Detroit Diesel makes these engines in 3 displacement
 sizes; DD13-12.8L, DD15-14.8L and DD16-15.6L. The diesel engine
 operating ranges will be 1200 to 2100 RPM. They will likely be
 driving down the road at 1400-1500RPM. The 20B for AC use will run between
 6000 and 7500RPM. The RPM difference evens out the displacement
 difference and the DD15 components look like a good match. The DD16
 turbo may be better for extended use on the 20B. Max boost may be
 down, but the turbo may last longer. The DD13 components may work on
 a p-port 13B especially with a 3.17 PSRU. Of course parts
 availability and cost are to be considered. The DD13 should be a big
 seller in the urban delivery market while the DD15 is aimed at the
 hi-way truck market. The DD16 will have a more limited appeal to
 long haul drivers and more in the Owner/Operator arena.

 Dale Davies

 I am not sure the smaller DD13 is turbo compound.

 Paul Lamar

 Yes it looks like you are correct on that. The sight does say for max fuel
economy on the DD13 engine to gear the truck for 1350RPM at65MPH. About
standard for truck engines. The math for the DD15 and DD16 for basic
displacement air moved can be calculated using that and then cross reference
to the 13B or 20B at 6000RPM for cruise. The DD15 should work fairly well on
the 20B. The one thing to watch out for is that the turbo or the axial flow
are not different between power ranges. The turbocharger from the DD16
combined with the power recovery from the DD15 might work.

Dale Davies



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