I can understand your skepticism, William and they may
well be overly "optimistic" about fuel economy with the 16X as well.
However, higher torque, the direct injection and the
improved combustion chamber geometry (and less rpm as you point out)
should provide some improvement over the current design - and any
improvement would only make it better for aircraft usage.
But, regardless as to whether the claims for
increase economy pan out or not - so long as it brings the torque/power increase
and lower weight, the old iron in my Rv-6A will get replaced by the 16X -
provided they do it within the next 3-4 years.
We will see.
Ed
Sent: Friday, April 15, 2011 2:07 PM
Subject: [FlyRotary] Re: 16X Torque and Fuel
Economy
The claimed fuel economy improvement in the Renesis was not
really found at all. In fact, most RX-8's got worse fuel economy than
non-turbo RX-7's (and quite a few of the turbo ones). Partly this is
because the RX-8 is a heavier car than the RX-7, but basically the Renesis is
just not all that efficient in real-world conditions. Maybe in the
lab.
Because of the generally disappointing performance of the Renesis
engine - which was less efficient, less reliable, and less powerful than
originally advertised, and on two of those three categories also compares
unfavorably to the (then) 40 year old 13B design, I have somewhat of a skeptical
attitude toward the 16X.
Certainly I think the concept - increase the
eccentricity for more torque and less revs - makes sense. The existing
Renesis was limited in RPM more by the available transmissions than by its own
capabilities, and thermodynamic efficiency (already the weak point of the rotary
design) decreases at high RPM. Even with a "long stroke" design the 16X
will still be a high revving, free wheeling engine and should retain most of the
rotary character.
But Mazda hasn't produced a genuinely good rotary
engine in 20 years. I admire their dedication, but they really need to
start getting it right.
On Fri, Apr 15, 2011 at 10:13 AM, Ed Anderson <eanderson@carolina.rr.com>
wrote:
Mazda claims that the 16X will have double the torque
(at all rpm) and better fuel economy at high engine speeds. The Renesis
claimed a 20% fuel improvement - but it appeared that was to be found at lower
rpm than we operate at. So hopefully the 16X will be kinder at our rpm
range.
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