Bill,

 

Running the supercharger. Part of this effort is to document EGT’s a different F/A ratios and MP’s. Part of my turbo planning to keep the EGT’s below 1600F.

 

Bobby

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Tuesday, May 09, 2017 5:24 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: F/A and EGT data

 

Bobby, While being under boost does change the intake side a bit ports and manifolds do have some effect. Exhaust systems have more effect. Are you still running the belt driven supercharger? Or have you gone turbo?

Bill 

 

On Tue, May 9, 2017 at 10:36 AM, Bobby J. Hughes <flyrotary@lancaironline.net> wrote:

Bill / Jeff,

 

In a normally aspirated engine I would agree. However under boost I think it’s safer to match F/A for each rotor under the most demanding conditions.  For me that’s 38-40” MP and 7000 rpm. But I can’t explain the inflight EGT changes just by twisting the mixture knob? I would expect the EGT spread would remain almost the same. I’m suspecting one of the injectors is not behaving properly.

 

MP	RPM	F/A- Combined	F/A Rotor 1	EGT Rotor 1	F/A Rotor 2	EGT Rotor 2	EGT Spread	Condition
31.0	5200	13.4		1524		1587	63	Flight
31.3	5200	15.7		1543		1558	15	Flight
31.2	5200	13.2		1525		1592	67	Flight

 

MP and RPM with constant speed prop were steady for this test. Fuel Map table address being used were stable. Some bouncing between two adjacent addresses with similar programmed values. Slower airspeed at 15.7 F/A but the constant speed prop maintains the target rpm.

 

Bobby

 

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Tuesday, May 09, 2017 1:11 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: F/A and EGT data

 

Bobby, I agree with Jeff. Since there are ALWAYS minor variances in the intake, porting, exhaust lengths, or even the actual bends of the exhaust it is unlikely that you will remain synced up across the range. I talked to Ross Farnham at SDSEFI and he commented that was why he put tune on the fly ability for individual cylinders / rotors into his EFI.

Bill Jepson

 

On Tue, May 9, 2017 at 8:44 AM, Jeff Whaley <flyrotary@lancaironline.net> wrote:

From memory, reading the EC2 Manual it states that rotor balancing should be performed at your preferred cruise rpm as it will remain balanced over a very narrow range. I'm sure you know: Static and in-flight engine performance will not be the same, regardless if the RPMs and MPs are matched.
Jeff

From:   Bobby J. Hughes <flyrotary@lancaironline.net>
Subject:        F/A and EGT data
Date:   Tue, 9 May 2017 10:12:07 -0500
To:     Rotary motors in aircraft <flyrotary@lancaironline.net>

I recently purchased a two channel  portable wideband O2 system and installed bungs and plugs on each exhaust runner. I also have a downstream wideband that I have been using for several years. I was able to spend a very productive hour ground tuning and adjusting Mode 4 injector balance prior to my flight yesterday from Austin to Akron OH. I'm not sure what to make of the F/A EGT spread data I collect during yesterday's flight.

During the ground tuning session I balanced rotor 1 to match rotor 2 using F/A ratios for takeoff condition. This produced very close EGT readings. However at my preferred cruise settings I'm seeing a large EGT spread. I would expect a consistent EGT ratio change when adjusting the mixture knob at a steady rpm / MP.  This appears not to be the case. What am I missing?

Bobby Hughes
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