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We are not comparing apples to apples
here. We have tried to compare NA engines with similar props before, but
this is the first time we have compared turboed and IVOed engines. This should
really give us some comparison data if we make certain we know what we are
comparing.
There is no way that 42” MAP is
going to give you 5800 rpm when 35” MAP will give you 6250 rpm with the
same prop and psru.
By the way, Chris, is your fuel pressure
dropping when your rpm drops? If your engine hits an rpm, it should
maintain that rpm unless the fuel flow drops. Is it going lean at high
rpm?
Chris and John, would you guys
please give us the particulars of your setups and then maybe some performance data
points?
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of John Slade
Sent: Wednesday, May 26, 2010
10:16 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Rotary HP
reviisted....now that I know more about it all...kinda.
Chris,
My rpm doesn't go down at WOT during a runup, but it does hit a ceiling. If I
tweak the mixture knob to the right about 1/4 turn the rpm goes up some more.
You might try that. There are some differences in our numbers, though - I get
about 5800 rpm full fine on a 66" 3 blade IVO with 42 MAP. Part of this
could be differences in the aspect ratio of our turbos. You'll also notice that
the rpm will climb as your speed builds. My 5800 will translate to 6300 in
climb-out and, if I'm heading out of the pattern and there's no 172 ahead, I'll
add a bit of pitch to the prop at this point to bring the rpm back down, and
the speed up.
Regards,
John
Chris Barber wrote:
I know this must have been discussed, but perhaps
more in passing or in some of Tracy's
literature (now kinda dated, especially with some of the strides he
continues to make), but what is the conventional wisdom as to rotary
horsepower? I know when I first started looking into it, oh many years
ago, it seemed the impression I got was that you could pretty easily achieve
200 hp, however, that is now a bit lower. Some of the tricks to get the
higher HP was mild and medium porting, bridge, "J" and "P"
porting. Then there was the option of turbo...the one, in combination
with a medium street port, I chose.
When started today, mine was turning about 6200 rpm
at 35 MP (with a 3 lb spring in the wastegate).....it surged forward against
the chocks and breaks. IVO prop full fine. Nice feel of power even
if it likes to heat up fast in 90 degree weather like this.
Also, I think this was discussed before too, when I
go WOT my engine develops up to about 6250 rpm, but then drops a
couple/few hundred rpm to usually just under 6000....sometimes just
above. Thoughts? Ed, (perhaps Al)it seems you may have chimed in
before. Regrettably, when I search the archives I tend to get
frustrated due to thread drift.
I heard a lot about porting when I was initially
investigating all this and I chose to use a medium street port. I
let Mazdatrix do the work. That being said, I have read all but
nothing on others porting their engines (other than a LOT
from PL on P ports). Since standard porting does not reportedly effect
reliability, only, potentially low low idle (I can idle as low as about
1300 rpm when warm smoothly) why is it not discussed and/or utilized more?
Just curious guys/gals. Discuss <g>
Always loved the lines of a Tailwind
– in fact, I have the plans and license to build a W-10 sitting on my
book shelf. Unfortunately, I doubt I’ll ever get around to it.
Ok with thermostat in the system holding
it at 190F – we really won’t know how much reserve capacity you
have in your cooling system until the power goes up.
I agree with George, 200HP out of an N/A
13B is really pushing it. I think 180HP is a more realistic expectation
– but, hey you never know. It amazing how power goes up when things
come together.
Enjoy and fly safe.
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of John
Sent: Wednesday, May 26, 2010 2:36
PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Emailing: 3
view w-10 003, first flight
My most humble thank you to flyrotary and all you
fine folks that have helped bring my project to flight. Ed and
many others whom I won't try to name here because I would miss many. The
plane is a Wittman Tailwind W-10, empty wt. is 981 and it is a tri-gear,
Wt. is within 6 #'s of similar trikes w/ 0-320 engines. I have the
thermostat in the engine because most of the year it is not very hot, if we get
50 days with the temperature over 70, we have had a hot summer, not a lot of
beach bunny activity. 7-1 I'll be 74 and have realized my dream, now it's
all gravy. Again, thanks guys!! JohnD
Your message is ready to
be sent with the following file or link attachments:
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