O2 sensor

[Ramjet555]

I'm putting on an ECU on my 2.2L engine and notice that it has 4 exhausts
and the O2 suggestions all talk from a car exhaust perspective to put the O2 censor
just after where two pipes meet.
How have others put in their O2 censors on RAF Subaru engines?

 

[dabkb2]

If you run avgas it won't matter, the lead will plug

 

[Ramjet555]

Thanks, I was planning on just using cheaper Premium gas

 

[Waddles]

The first photo is of an original RAF exhaust that was modified to accept an Oxy Sensor. It was attached to an after-market ECU (Motec) and I used it to set the AFR. The sensor worked just fine and there were no problems with the engine. Using this, the fuel burn improved significantly finishing up at around 20 litres per four.

The second is fitted to my current RAF and is hooked into the Subaru ECU, no AFR gauge. Again, fuel consumption is around 20 litres per hour overall average.

In both cases, the engines are EJ25s with Autoflight redrives and neither showed any temp problems. Fuel is Mogas normally but I have used Avgas as a top-up to "get home".

 

[Ramjet555]

Thanks Waddles,
Exactly what I needed to see.
Which is the better way to go, on the side of the can
or just prior to the can.
Mine has 4 exhausts going to the can which also has
a carb heat input and output.

 

[Waddles]

I'm not really sure, but logic would dictate that in the can before the exhaust outlet would sample the AFR from all cylinders for a reasonable average reading.
As I said, the fuel consumption on both installations was pretty much the same with the same redrive and prop on both. Don't know if that proves anything. I do know that in the installation with the AFR gauge, after I adjusted the AFR the consumption dropped from 26 litres per hour to 20. Final setting was around 13 to 13.2.
I guess that ease of installation comes into play as well.

 

[AirCommandPilot]

Make sure it's not too close to the open end of the pipe. If you get fresh air hitting it at any point, it will read lean.