ccsmith51

ccsmith51

Well Known Member
I have an 02 sensor and the air /fuel ration gauge below:

1zzhu8w.jpg


I have an O-360 in my RV-4. I'm thinking about installing this gauge in the panel, and the sensor near the EGT probe.

Does anyone have an air / fuel indicating system installed?

Would this be a beneficial addition to my panel?

Thanks,
 
If you're burning 100LL the oxygen sensor will likely have a very short life.
 
True...

airguy said:
If you're burning 100LL the oxygen sensor will likely have a very short life.
Click to expand...

I burn 100LL, and I'm told the sensors last 100 hours or so on average. I'm looking into running 91/93 non-ethanol unleaded mogas if I can find it economically and conveniently. That would certainly extend the sensor life.

I have only one CHT and EGT. My question regarding the meter is, would the meter allow me to lean better, when compared to pull the knob until rough then push it back in. If so, and I got lower fuel consumption, then the savings would certainly pay for a $30 sensor every 100 hours or so....

I read an article on leaning aircraft engines and found the following:

"The fuel / air ratio for best power is around 1:13 and for best specific fuel consumption (SFC) it is 1:17. Peak EGT occurs at the chemically correct ratio of 1:14.7 and peak CHT at a slightly richer ratio."

On my meter the center two green LED's light at 1:14.7.
 
Last edited:
I suspect narrow band (wide band are pretty expensive, the sensor is bulky), in which case it's worthless to you IMO. If O2 sensors were an accurate/reliable way to meter fuel over EGT I think we would've seen it on production engines by now. The other piece of that puzzle is you don't have a MAF to tell the system how much air is going in the front end, so how is it going to give you accurate info?
 
Since this is an automotive type air/fuel mixture indicator (Intellitronics ?), then I'd be worried that where it shows its green "happy" range is probably the stoichiometric ratio which might place a Lyclone aircraft engine right at peak CHT (between 25 and 50 ROP EGT) where you probably don't want to be running it continuously for very long.
 
Thanks for the replies and insights. It sounds like this arrangement will not provide me with any reasonable benefit. You have saved me a bunch of time that I can apply to other improvements in my recently purchased bird!!

With that in mind, with a carbureted engine, and only one EGT and one CHT, is the best way to lean to pull mixture until roughness, then richen until smooth?

BTW, that is what I was taught when I learned to fly in Cherokee's in the 70's. The A65 powered Champ in which I got my first 50 hours in the 60's had no mixture control at all!!

Thanks!!
 
ccsmith51 said:
With that in mind, with a carbureted engine, and only one EGT and one CHT, is the best way to lean to pull mixture until roughness, then richen until smooth?
Click to expand...

It works for me. I'll go two to three turns in, with the red knob. There are a range of temps I like to see on my EGT. Usually in the ballpark of 1325-1350. If it's lower, I know that I'll end up clearing the plugs during the mag check. Note: EGT's can vary between planes, depending on the exact location of the sensors. I'm just running one on cyl. #3.

L.Adamson --- RV6A
 
The narrow band meters are not particularly useful or accurate as the sensor is really designed as a switch for ECUs to target stoichiometric mixture of around 14.7. They are not too accurate on either side of this. They output a 0-1V, non-linear signal.

Wideband types output a 0-5V linear signal and are highly accurate. They are the modern way to tune for best power and to see what the AFR is under all conditions. You can use Decalin Runup lead scavenger in your 100LL to extend sensor life.

EGTs work well too once you establish where best power is although more factors are involved there and it is somewhat indirect. EGTs work well for setting best mixture for LOP operation.
 
ccsmith51 said:
Thanks for the replies and insights. It sounds like this arrangement will not provide me with any reasonable benefit. You have saved me a bunch of time that I can apply to other improvements in my recently purchased bird!!

With that in mind, with a carbureted engine, and only one EGT and one CHT, is the best way to lean to pull mixture until roughness, then richen until smooth?

BTW, that is what I was taught when I learned to fly in Cherokee's in the 70's. The A65 powered Champ in which I got my first 50 hours in the 60's had no mixture control at all!!

Thanks!!
Click to expand...

Yep, you've got it.

Just one other consideration, don't pull that mixture with more than 23" of MP.
 
ccsmith51 said:
I have an 02 sensor and the air /fuel ration gauge below:

1zzhu8w.jpg


I have an O-360 in my RV-4. I'm thinking about installing this gauge in the panel, and the sensor near the EGT probe.

Does anyone have an air / fuel indicating system installed?

Would this be a beneficial addition to my panel?

Thanks,
Click to expand...

Check out this thread. Specifically post #8.

http://www.vansairforce.com/community/showthread.php?t=21631&highlight=oxygen+sensor

Then do a search on RV969wf's other posts regarding speed mods.

Joe
 
The fact remains that narrow band meters are only give a rough indication of AFRs. Your engine is worth a lot of money. If you want to use an AFR meter to set mixture, invest a bit more money and buy a wideband type. PLX makes a nice one: http://www.plxdevices.com/wideband.html

We've sold hundreds of these and dozens for setting up aviation engines with EFI. Very solid product and company.
 
When I flew my first plane, an RV4, in 95, it had a O2 sensor on it. There was a fella from Ontario Canada marketing this unit and I believe ACS had it listed for a while. The plan at that time was to operate rich of peak as most certified planes still do. You simply pulled the mixture back until a little light came on, which indicated the perfect stoichiometric ratio, and then you added a bit of fuel. It was crude by today's standards but pretty cool at that time.
Sensors lasted about 50 hours and I used the unit for about 100 hours. After that I really knew my engine and did feel that i needed it any longer. I have no idea what type of sensors they were but they were not that expensive and were available from any auto shop, I think they were a ford product.
 
I used this system on my RV4 for at least 14 years with very good results. I had an ellison TBI and used this as my source for leaning. It kept working long after my egt went south. The sensor worked well without the need to replace for around 700hrs. I simply had a nut welded on to my exhaust on my #4 cylinder about a foot down from the top (as I recall) for easy removal and installation. My indicator was the same as above. The part number of the sensor was a Bosh 12028 about 20 bucks at Napa and 10 minuets to replace.
Ryan
 
You must log in or register to reply here.