flyrotary@lancaironline.net Mailing List Archive

Thanks Lynn.

That puts things in perspective.

Come to think about it, that 1950°F could have been with a failing EGT probe.

I see that my engine monitor alarm is set at 1800°F and was set at 1750°F when I got it.

Do you happen to have any data from multiple EGT probe locations? I still would like to know how rapidly temps drop off as the distance increases from the port.

Here's some data from the LSU 4.9 wide band O2 sensor data sheet:
Operating temperatures
Exhaust gas <= 930 °C
Hexagon on sensor housing <= 600 °C
Cable outlet (PTFE molded hose) - Sensor side (PTFE protective sleeve) <= 250 °C
Cable outlet (PTFE molded hose) - Cable side (upper hose sleeve) <= 200 °C
Cable and protective hose <= 250 °C
Connector <= 120 °C
Maximum temperatures (max. 250 h cumulative over service life)
Exhaust gas <= 1030 °C
Hexagon on sensor housing <= 680 °C

So brief excursions to 1,900°F should be OK.

I may just install the LSU 4.9 in the current bung location and keep an eye on EGTs.

Finn

On 5/18/2020 7:59 PM, lehanover lehanover@aol.com wrote:

With EGTs close to 2,000 degrees, when 1650 would be a bit high in my book.......apex seals will be fighting over who gets to peel off the chrome first. The ideal mixture for best power in piston or rotary also produces

(and is evidence of) close to the highest EGT. So a bit richer or a bit leaner than ideal is the order of the day.

She was runnin best ever just before the piston melted.

Mr Drummond had us mount the EGT probes 3" from the port face on the outside of any bend with the probe tip in the center of the tube. And even then looking for 1650 degrees or less. The rotary has an unburned hydrocarbon problem from the cold combustion chamber. So, a bit more ignition advance can get more of the burn completed before the port opens. 23 to 24 degrees on pump gas, maybe 24 to 27 degrees on avgas or racing gas. High octane fuel is not required unless boosting is used.

This information might also be worth what you paid for it.

Lynn E. Hanover

In a message dated 5/18/2020 5:12:27 PM Eastern Standard Time, flyrotary@lancaironline.net writes:
Sorry; I should have included a message with that link. I suspect that with a little digging, a model could be located that would allow modification to emulate what Steve's device does. Of course, if someone (Tracy) has a metal lathe...

Charlie

Virus-free. www.avast.com
On Mon, May 18, 2020 at 2:05 PM Charlie England ceengland7@gmail.com <flyrotary@lancaironline.net> wrote:
https://www.google.com/search?q=o2+sensor+bung+extension&oq=o2+sensor+bung+extension&aqs=chrome..69i57j69i65.7765j0j7&sourceid=chrome&ie=UTF-8

Virus-free. www.avast.com
On Mon, May 18, 2020 at 1:43 PM Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:
Thanks Steve.

Hadn't seen that before.

Work of art!

But, dang, $89 (or $58 on eBay). Could buy a couple new O2 sensors at that price.

Finn

On 5/18/2020 12:31 PM, Steven W. Boese SBoese@uwyo.edu wrote:
Finn,

FWIW, I've used the bung extender shown in the photos on my test stand without ill effects other than initial cost.

Steve Boese

From: Rotary motors in aircraft <flyrotary@lancaironline.net> on behalf of Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net>
Sent: Monday, May 18, 2020 7:55 AM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] O2 sensor location

◆ This message was sent from a non-UWYO address. Please exercise caution when clicking links or opening attachments from external sources.

So I bought the Bosch LSU 4.9 wideband oxygen sensor and ALM-board.

Specs for the LSU 4.9 says max operating temperature is 930 °C (1700°F).

I recall seeing 1950F EGT temps on my 13B with EGT probes 8" from the
side of the engine.

On the RV-4 Renesis, before buying the wideband sensor, I welded the
bung 12" from the closest port. (Stock manifold cut and 180° turn at
exhaust port nearest flywheel, 2.5" pipe.)

I expect the Renesis to have slightly lower EGT temps, but am worrying
about damaging the O2 sensor.

Charlie suggests mounting the sensor on a longer bung, moving the sensor
out of the direct gas stream, but I feel that may reduce the accuracy of it.

My plan was to use the cheap narrowband O2 sensor initially and find the
engine settings giving highest EGTs, then temporarily mount an EGT probe
in the O2 bung hole, run the engine at those settings and see if EGT
there was safe for the wideband sensor.

But maybe I'm worrying about nothing.

Do any of you have data on how rapidly the temps drop as a function of
distance from exhaust port?

Finn
--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html
Virus-free. www.avast.com