Mailing List flyrotary@lancaironline.net Message #54527
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Re: [FlyRotary] Re: 16X Torque and Fuel Economy
Date: Fri, 15 Apr 2011 14:52:24 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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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