Finn,

 

I did a lot of testing / tuning trying to get my EGT’s balanced. If I balanced for full power then my cruise settings would have a large spread. Changing my electric prop rpm a little would narrow the spread. I even welded a wideband O2 bung on each runner for grounding tuning. I could balance the F/A at 30-38” MP and have my EGT’s match within a couple of degrees. With this balanced I would see an 80-100F spread at 4800 rpm. Less spread at 5200 rpm, etc. F/A managed to keep the EGT’s in the low 1600’s at full power. Lean cruise in the mid-1500’s.

 

I have a portable dual wideband O2 kit you can borrow if you have room to weld in bungs for testing.

 

Bobby

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Wednesday, April 28, 2021 7:44 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: EGT probes location

 

Thanks Neil, Steve, Matt and Charlie.

I did try to get tip of probes centered in the openings, but now I remember that a very slight difference made a significant difference in readings during initial engine runs.

So I think I'll ignore it for now (and set the alarm higher). Then later on I can try to adjust the front/rear rotor fuel ratio. Perhaps watching fuel flow vs RPM will be a better way to optimize this?

Definitely a disadvantage to using the stock exhaust manifold. The ideal setup would probably be separate (outer) runners, perhaps with an O2 sensor in each runner.

Finn

On 4/28/2021 7:21 PM, Matt Boiteau mattboiteau@gmail.com wrote:

Cyl 1 will be hotter since it gets the coolant the last. I can be anywhere from 50-100f difference sometimes.

I think too, with our high temperatures, the accuracy of the probes probably have a good amount of +/- in there.

- Matt Boiteau

 

 

On Wed, Apr 28, 2021 at 7:15 PM Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:

Hi Finn

Yes.
An example of our EGT’s at WOT take off - Lambda ~0.9 / AFR 13.3
1598 & 1679 - So 81 higher.
I’m not sure our EGT probes are inserted exactly the same distance into the header.
Not sure the variation in temp this might cause.
One of our probes is burnt out now.

Cheers

Steve Izett


> On 29 Apr 2021, at 5:30 am, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:
>
> So, I'm using the Renesis stock exhaust manifold.
>
> Tried to mount the EGT probes as close as possible and same distance from the ports.
>
> However, at high power I'm seeing as much as 120F higher on rotor 2.
>
> Exhaust gas from rotor 1 passes by rotor 2 exhaust port so I'm wondering if that somehow increases rotor 2 EGT readings.
>
> Caught my attention today when EGT2 got above 1,800F at 6,200 RPM and 161 mph TAS @ 3,300' density altitude.
>
> Any of you that's using the stock exhaust manifold run into this?
>
> Finn
>
>
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