Tuning an AeroInjector without EGT ?

[hans]

Hi Group,

after the first couple of flights in my S-II, the engine is again stalling every now and then (at low revs when taxiing) and in one instance even ran rough when turning 3000-3100 RMP, the latter of which made me decide to abort take-off.
I attribute this to having tried to tune the carb without having an EGT, and as AeroInjector-owners know, the manual specifies the tuning effort with references to EGT-temps and EGT-deltas only.

Kerry (of Monnett/AeroConversion) wrote to me that I could do a WOT test to check whether when leaning the CHT's go up, as they should. This only shows that the mixture can still be leaned somewhat (i.e. is not overy rich), but not much more.

Do I really need to get an EGT installed for a proper tuning, or do alternative tuning methods exist that provide better than 'guestimate' settings?

thanks,

Hans

____
Sonerai II 'PH-ERA'

[schrome]

Hans,

Even with a gauge I spent a lot of time trying to tune the Aerocarb by EGT delta. Seems no matter what I did I couldn’t get the 50 deg. movement when leaning at WOT. Finally I gave up and just took off because otherwise the VW was running fine - it accepted throttle without balking and the static rpm was good and strong. So for purely selfish reasons I recommend that you install a gauge and let me know whether your experience is any different! :-)

Ed

[hans]

Oct 3, 2011 11:30:14 GMT -5 schrome said:

Hans,

Even with a gauge I spent a lot of time trying to tune the Aerocarb by EGT delta. Seems no matter what I did I couldn’t get the 50 deg. movement when leaning at WOT. Finally I gave up and just took off because otherwise the VW was running fine - it accepted throttle without balking and the static rpm was good and strong. So for purely selfish reasons I recommend that you install a gauge and let me know whether your experience is any different! :-)

Ed

You're a real comfort!

What did you do to arrive at the tune setting that works so well for you?

cheers
Hans

[schrome]

Hans, after reading what I wrote in my builder's log (they're good for something) I'd like to amend what I said earlier. The Aerocarb manual wants 90-100 deg F rise when leaning at WOT and 40 was the best I could get. That's the setting I went with.

I suspect it may be a bit on the lean side but I have to get the plane flying again before I make any further adjustments.

Ed

[hans]

Thanks Ed!

so you did use EGT after all, ok. Are you sure that a delta of only 40°F means that you're on the lean side?

cheers
Hans

[schrome]

Occasionally while taxiing after a flight the engine dies suddenly. I've fiddled with the idle adjustment without success so my next move will be to enrichen it a tad. Second problem is that the engine sputters at very high angle of attack, such as the approach to a stall. I believe the air at the cowling outlet is curling up into the cowling and overwhelming the carb, and maybe a little more fuel will help the situation. Keep in mind these are my conjectures, not proven facts.

It's been almost a year since I've flown it and I'm not 100% sure about this, but I seem to recall that I see more EGT rise when leaning in flight than during a static test on the ground.

Ed

[oahupilot]

stick a wide band a/f meter in you exhaust pipe and see how you are actually burning fuel instead of guessing.

[hans]

Oct 4, 2011 15:44:45 GMT -5 oahupilot said:

stick a wide band a/f meter in you exhaust pipe and see how you are actually burning fuel instead of guessing.

I've thought of that, but these sensors need to be heated to get accurate readings - and since my engine doesn't sport an alternator....

Hans

[oahupilot]

hans

they sell hand held a/f wide band o2 sensors just for tunning carbs

[hans]

Oct 8, 2011 2:42:24 GMT -5 oahupilot said:

hans

they sell hand held a/f wide band o2 sensors just for tunning carbs

That's cool, I didn't know that. Going to search for them now...

Hans

[hans]

O.k, I bite the bullet and purchased two of these tiny EGT gauges and probes from UMA. The next couple of weeks I'm going to install them on both rear exhaust stacks. In the long run, all four of hem are going to be instrumented, but this has to do for now.
After that I should get my AeroInjector tuned to specs, keeping my fingers crosses!

cheers
Hans

[4trade]

Hans, please, remember keep us posted for your results and how all went together overall.

[hans]

Nov 12, 2011 11:44:18 GMT -5 4trade said:

Hans, please, remember keep us posted for your results and how all went together overall.

I'll keep a log to later create a document for our new Sonerai.net. This current board doesn't lend itself too well as a community supporting repository.

cheers
Hans

[peterzabriskie]

Hans, et.al. Sonerai board member Tom posted a link to a good source for cheap(inexpensive) EGT guages. Auberins: www.auberins.com/index.php?main_page=index&cPath=5_26
-Pete

[n3480h]

The Auber Instrument gages are a single circuit digital numerical readout gage which can be coupled and programmed for a variety of sensors and probes. My inquiry to them about whether or not I could utilize a digital switching circuit to display more than one source, was "Yes, that can be done". My thought was to provide an automatic switching circuit to rotate through readout displays for EGT, CHT, Oil Pressure, Oil Temp and so on, all through one lightweight display. A line of LEDs could indicate which probe result was being displayed at any given moment. Pause time for each display could be programmed on a separate (very small) circuit. This could also probably be done with a manual rotary switch, but where's the fun in that?

I have one of the display units and it is a neat little deal. About 2.5" wide, 1.25" tall, and maybe 3" deep. Might be about 3-4 ounces. Runs on 12VDC with very low current drain. I can't imagine a more lightweight instrument panel.

Tom