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Ok, didn't have your manifold pressure at run up so I
assume 29" Hg (1" of loss). Based on that assumption, 6300 rpm and the
fuel flow of 14.1 gph, I came up with 153 HP. Now to get that with a 14.1
GPH fuel flow it took an A/R of 17:1, (leaner than your stated A/R). Since
you mentioned that you have not yet calibrated the fuel flow, I suspect
that you might be flow more fue -l in which base the HP number would go up and
the A/R down.
Generally best power is found at an A/R of around 12.6:1 -
if I plug that value in at 6300 rpm this is what you should theoretically
see:
6300 RPM A/R 12.6:1 (Best Power) and 29" Hg MAP
= 206HP and 19.1 GPH fuel flow. So you’re A/R plays a key role
in power being produced at any rpm .
So next time if you can, get your manifold pressure
reading and I can give you a better estimate although until you have the fuel
flow calibrated its likely to be inaccurate.
Ed
Sent: Wednesday, August 22, 2012 11:20 PM
Subject: [FlyRotary] Re: Prop revs
ED and all.
Ran up to 6300 revs (approx) and
the fuel flow was showing 14.1 GPH at 14 A/F ratio. Not sure that the fuel
flow is correct as has not been set yet. This is Tracy’s standard setting so
far. Engine is lumpy under 1800 rpm and has its moments until over
3000 rpm when everything acts normally. Suspect that part of the blame may be
the slide throttle. Have 6.5 hours on the ground so far and will check for
another few hours yet. Full noise gives an EGT of 1770, so will have to up
the alarm limit to 1800. Finally fixed all the oil and water leaks. Any
advice re what to check next before take off ? Neil.
Sent: Thursday, August 23, 2012 9:21 AM
Subject: [FlyRotary] Re: Prop revs
Hi
Ed
Thanks for the offer but I'm not flying yet.
Hopefully early next year.
Steve Izett
Glasair SIIRG Renesis 4 port RD1C EC2 EM3
On 22/08/2012, at 8:51 PM, Ed Anderson wrote:
Steve, if you give me the fuel flow you are seeing at
6300 rpm and manifold pressure, I can give you a pretty good estimate from my
spreadsheet of what power you are producing. Also should you happen to
have the Air/Fuel ratio that would be a plus but not essential.
Ed
Sent: Tuesday, August 21, 2012 7:23 PM
Subject: [FlyRotary] Re: Prop revs
Thanks Ed
I've wondered what my Renesis 4 port with a good intake manifold and in
flight adjustable prop will produce.
So on a cold day she will hopefully still breath to 7250RPM and maybe
approach 200HP?
Cheers
Steve Izett
On 21/08/2012, at 11:40 PM, Ed Anderson wrote:
Steve,
On a cold morning when I can see 19-20 gph on take off
at 6200 rpm, I calculate based on fuel burn rate and an air/fuel ratio of
12.65:1 that I am probably producing around 180-185 HP. On hot days
based on fuel burn of 16.5-17.0 GPH, I calculate around 165-170
HP.
The fastest I've ever had the Rv-6A was 200 mph TAS
burning round 13.25-14.5 GPH.
But, none of this was done on a dyno - its based on
fuel burn and rpm and we all know a rotary can pass through more fuel
than is producing power. Anyhow, it’s the best estimate I have.
Ed
Sent: Tuesday, August 21, 2012 10:31 AM
Subject: [FlyRotary] Re: Prop revs
Ed
Out of interest, what do you think you are getting in HP from your 13B
and at what RPM?
Steve Izett
On 21/08/2012, at 9:15 PM, Ed Anderson wrote:
I would say you have winner. Does of
course depend on what prop load you were pulling during static run.
I have a fixed pitch 74x88 and a well-tuned older
13B and the best I have ever got static - was 6200 rpm on a cold
day. Normally, I get 6000-6100 rpm.
So depending on your prop, it looks like you are
doing great for static rpm.
Ed
Sent: Monday, August 20, 2012 9:48 PM
Subject: [FlyRotary] Prop revs
All,
Looks like I am finally
connected after many attempts.. I have a P ported renesis in a
glastar that is ready to fly. Tuning the motor yesterday to find
that I cannot get the motor revs over 6300. I suspected the prop
(prince fixed) is too big, but am assured that that is normal as a static
load. Lonnie suggests that once moving the extra revs will
appear. How do I tune the motor for the top end revs? Any
advice? Neil.
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