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Subject: Re: [FlyRotary] BSFC was  [FlyRotary] Re: Fw: Different Rotary Port
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Date: Tue, 19 Jun 2007 10:30:59 -0400
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Ed,
Your comments indicate that you understood me correctly. What everybody=20
on the list needs to know is that the best milage economy piston engine=20
you may find will likely have almost as much overlap as a rotary=20
p-port. Engine designers have found that a certain amount of overlap is=20
better. To speak generally, at low RPMS or idle minimal overlap is=20
best, but at higher RPMS increased interaction between exhaust and=20
intake helps cylinder filling. The rotary works differently than a=20
piston engine of course, but my point is that the specifics of the "no=20
overlap" timing on the renesis are not the major reason it makes more=20
power. The larger ports and higher RPMS are.
Bill Jepson

-----Original Message-----
From: Ed Anderson <eanderson@carolina.rr.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Tue, 19 Jun 2007 5:26 am
Subject: [FlyRotary] BSFC was [FlyRotary] Re: Fw: Different Rotary Port=20
configurations


Ok, Bill, I think we agreed that a stock Renesis could be cheaper than=20
a PP (all depending on price paid for either, of course).=A0

=A0

=A0However, I'm not certain I fully understood whether my comment about=20
the Renesis betting a better specific Fuel consumption than a PP was=A0an=20
=A0area of disagreement.=A0 It appears it was.

=A0

=A0 I must admit some degree of ignorance in this area , however, I=20
always thought that getting better SFC was due (at least in part)=20
better use of each unit of fuel to produce useful mechanical work.=A0 So,=20
if I understood you correctly, you are saying that the PP which has all=20
this overlap gets a better SFC than the Renesis which can better=20
contain the combustion process (no overlap).=A0 I must admit that=20
surprises me.=A0 But, always willing to learn.

=A0

ED


----- Original Message -----

From: WRJJRS@aol.com

To: Rotary motors in aircraft

Sent: Tuesday, June 19, 2007 1:19 AM

Subject: [FlyRotary] Re: Fw: Different Rotary Port configurations


In a message dated 6/18/2007 4:30:46 PM Pacific Standard Time,=20
eanderson@carolina.rr.com writes:

Renesis will undoubtedly get a better specific fuel consumption than a=20
PP.

=A0 So for those that want the utmost in power, it sounds like the PP is=20
the
way to go.=A0 For other cheap old chaps the Renesis would appear to offer=20
a
cost effective power increase.

Ed


Here Ed I have to totally DISagree.=A0The side ported engine is used to=20
provide more power, and has bigger side ports only workable with the=20
Renesis,=A0but must also=A0pass smog regulations and provide low-end torque=20
for car use. The need for the higher redline is the total giveaway. For=20
ANY i.c.e. the key to higher bmep is higher RPM. Spin your 13B to 9k=20
and provide it with an adaquate intake and exhaust I would bet money=20
you will be within a few HP. While I don't want to sound like a broken=20
record, and certainly not trying to be contentious, Mazda built the 26B=20
for use in a race using an economy formula. If side ports were more=20
efficient they would have used them!=A0 P-ports make more power, but in=20
the low to midrange so critical in a car they are much dirtier on HC. I=20
really believe that the Renesis came from Mazda's hydrogen experiments.=20
The ability to produce large ports WITH NO OVERLAP was critical to the=20
success of that project. Much talk has been made of the fact that=20
p-port rotaries have considerable overlap in the exhaust to intake=20
phase. So does every high performance piston engine ever built. Tuners=20
have even found the overlap phase to be beneficial to performance when=20
the engine is properly tuned. The reason for the renesis is IMHO the=20
need to pass smog and provide competitive power, Not that the Renesis=20
is the "best" configuration. I'm glad they're building it since it is=20
the key to Rotary survival. I simply harbor no delusions that Mazda=20
wouldn't run a p-port with variable length intake tract if smog and=20
noise would allow it. The advent of truly functional Direct injection=20
may make the return of p-ports possible, but there is now a lot of=20
inertia against them.

=A0As for cheaper I agree.=A0Anything over-the-counter is a less expensive=20
solution!=A0

Bill Jepson


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