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Thanks, Bill
Always an education, when talking about intake/port configurations (and many other things) on this list. Seems what might appear at first blush to be the case - isn't.
Yes, I had though that if I had my 13B dynamically balanced, the rotors and counterweighs lighten, and perhaps a bit more oil pressure, that my old 13B would get up there in the ball park with the Renesis power-wise, but when I considered the cost - I decided it would probably be smarter to go with a newer model engine rather than spend that money on modifying the older 13B.
Besides, if I produced any more power, I would have to "adjust" my cooling system to handle the greater heat rejection required. Sigh, are there no simply changes? {:>)
Ed
----- Original Message ----- From: <wrjjrs@aol.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, June 19, 2007 10:30 AM
Subject: [FlyRotary] Re: BSFC was [FlyRotary] Re: Fw: Different Rotary Port configurations
Ed,
Your comments indicate that you understood me correctly. What everybody
on the list needs to know is that the best milage economy piston engine
you may find will likely have almost as much overlap as a rotary
p-port. Engine designers have found that a certain amount of overlap is
better. To speak generally, at low RPMS or idle minimal overlap is
best, but at higher RPMS increased interaction between exhaust and
intake helps cylinder filling. The rotary works differently than a
piston engine of course, but my point is that the specifics of the "no
overlap" timing on the renesis are not the major reason it makes more
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
configurations
Ok, Bill, I think we agreed that a stock Renesis could be cheaper than
a PP (all depending on price paid for either, of course).
However, I'm not certain I fully understood whether my comment about
the Renesis betting a better specific Fuel consumption than a PP was an
area of disagreement. It appears it was.
I must admit some degree of ignorance in this area , however, I
always thought that getting better SFC was due (at least in part)
better use of each unit of fuel to produce useful mechanical work. So,
if I understood you correctly, you are saying that the PP which has all
this overlap gets a better SFC than the Renesis which can better
contain the combustion process (no overlap). I must admit that
surprises me. But, always willing to learn.
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,
eanderson@carolina.rr.com writes:
Renesis will undoubtedly get a better specific fuel consumption than a
PP.
So for those that want the utmost in power, it sounds like the PP is
the
way to go. For other cheap old chaps the Renesis would appear to offer
a
cost effective power increase.
Ed
Here Ed I have to totally DISagree. The side ported engine is used to
provide more power, and has bigger side ports only workable with the
Renesis, but must also pass smog regulations and provide low-end torque
for car use. The need for the higher redline is the total giveaway. For
ANY i.c.e. the key to higher bmep is higher RPM. Spin your 13B to 9k
and provide it with an adaquate intake and exhaust I would bet money
you will be within a few HP. While I don't want to sound like a broken
record, and certainly not trying to be contentious, Mazda built the 26B
for use in a race using an economy formula. If side ports were more
efficient they would have used them! P-ports make more power, but in
the low to midrange so critical in a car they are much dirtier on HC. I
really believe that the Renesis came from Mazda's hydrogen experiments.
The ability to produce large ports WITH NO OVERLAP was critical to the
success of that project. Much talk has been made of the fact that
p-port rotaries have considerable overlap in the exhaust to intake
phase. So does every high performance piston engine ever built. Tuners
have even found the overlap phase to be beneficial to performance when
the engine is properly tuned. The reason for the renesis is IMHO the
need to pass smog and provide competitive power, Not that the Renesis
is the "best" configuration. I'm glad they're building it since it is
the key to Rotary survival. I simply harbor no delusions that Mazda
wouldn't run a p-port with variable length intake tract if smog and
noise would allow it. The advent of truly functional Direct injection
may make the return of p-ports possible, but there is now a lot of
inertia against them.
As for cheaper I agree. Anything over-the-counter is a less expensive
solution!
Bill Jepson
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