FlyEFII System32 factory tour and system review

[rocketman1988]

I tried the O2 sensor in my early setup and tuning and despite multiple sensors and controllers could never get anything even remotely close to consistent readings. My running hypothesis is that the multiple slip joints on the Rocket exhaust was simply letting too much outside O2 in and polluting the readings. Does your 10 have a ”tight“ gas path from cylinder to sensor?

Yes, I have the custom aircraft exhaust; three into one collector. The O2 sensor is located in the #6 stack so there are no leaks, just exhaust gas.

 

[Toobuilder]

Yes, I have the custom aircraft exhaust; three into one collector. The O2 sensor is located in the #6 stack so there are no leaks, just exhaust gas.

OK, so word to the wise out there - it does not take much of a leak to corrupt the O2 sensor. I think “properly installed” does not include slip joints in the path ahead of the sensor. I should have known that.

 

[dmattmul]

OK, so word to the wise out there - it does not take much of a leak to corrupt the O2 sensor. I think “properly installed” does not include slip joints in the path ahead of the sensor. I should have known that.

My O2 sensor is located ~ 6 inches downstream of #4 exhaust well in front of any slip joints. My first several sensors never made it to the next oil change (I change oil at 25 hrs. and filter at 50) At ~ 150 hrs. installed a timer and delayed turning on the PLX system for 2 mins after engine start. That seemed to help. Several O2 sensors made it to the next oil change, and several made it to 2nd oil change. After this really didn't need the O2 sensor to understand where I was running rich or lean so stopped changing the sensor. I doubt our current O2 sensors will last long enough to make changing it at conditional SOP as long as we are using 100LL. If anyone has a magic bullet would love to hear it.

 

[rocketman1988]

My O2 sensor is located ~ 6 inches downstream of #4 exhaust well in front of any slip joints. My first several sensors never made it to the next oil change (I change oil at 25 hrs. and filter at 50) At ~ 150 hrs. installed a timer and delayed turning on the PLX system for 2 mins after engine start. That seemed to help. Several O2 sensors made it to the next oil change, and several made it to 2nd oil change. After this really didn't need the O2 sensor to understand where I was running rich or lean so stopped changing the sensor. I doubt our current O2 sensors will last long enough to make changing it at conditional SOP as long as we are using 100LL. If anyone has a magic bullet would love to hear it.

Exactly. That's why I asked how a previous poster was getting 100 - 200 hours on a sensor.

I haven't seen an answer.

 

[rongawer]

All of that said, the engines ran fine, without issue on the 155L pump. It wasn't until we were looking at the data, that we found the loss of pressure, and we weren't specifically looking for it. Had we NOT been studying the actual data, we likely would never had known. There are more details to the story but they aren't really relevant to the discussion. I just summarized what we saw, and how it was resolved.

Good to know. You have my curiosity. I'm sensing fuel pressure at the regulator (Borla), which is the end of the injector loop and reflects "rail" pressure and has been pretty steady. Full loop flow testing provided 36 GPH at 50 PSI, which is a head scratcher for me when compared to your data. One thing to note is that I used AN8 suction piping and my Andair fuel valve is 1/2 on the supply with 3/8 on the return and uses a single Andair pre-filter, which is 62 µm on the pump rack. However, I'll be sure to trend pressure.

 

[rocketman1988]

Good to know. You have my curiosity. I'm sensing fuel pressure at the regulator (Borla), which is the end of the injector loop and reflects "rail" pressure and has been pretty steady. Full loop flow testing provided 36 GPH at 50 PSI, which is a head scratcher for me when compared to your data. One thing to note is that I used AN8 suction piping and my Andair fuel valve is 1/2 on the supply with 3/8 on the return and uses a single Andair pre-filter, which is 62 µm on the pump rack. However, I'll be sure to trend pressure.

Are you measuring that static or actual during full power engine runs?

No doubt the 1/2” supply makes a difference.

Please post if you find a pressure drop in your data.

 

[rongawer]

Can you detail "properly installed and setup" for the O2 sensor?

1. Installed >12" from the exhaust outlet. At least 18" from the exhaust port. Mine is at the 3:1 collector on the left exhaust.
2. installed > 10º up from level, but not more than 15º off vertical. Mine is about 45º up.
3. Wired properly per the diagram. Ensure the heating element is operational.
4. Operate in Resistor Calibration mode.
5. Use Decalin if possible, or other TCP additives. I haven't done any detailed testing to validate the impact of using this on an O2 sensor, but I've been running decalin for years on my experimental engines and it definitely reduces lead fouling of plugs and is touted by Decalin to reduce fouling of O2 sensors... seems to work.

 

[rongawer]

Are you measuring that static or actual during full power engine runs?

No doubt the 1/2” supply makes a difference.

Please post if you find a pressure drop in your data.

Absolutely, suction piping size makes a huge difference. With head loss being a squared function of flow, I agree that higher loads will definitely drop the net positive suction head for the pump, which is exactly why I did 1/2" suction lines.

I've done all of my fuel flow testing on my newest -10 on the ground. I'll keep you posted. BTW, if for some reason my pumps can't maintain 45 PSI at full power, I have no problem spending a couple hundred bucks to swap those out, but 25% loss of pump D/P is considerable.

 

[rocketman1988]

Absolutely, suction piping size makes a huge difference. With head loss being a squared function of flow, I agree that higher loads will definitely drop the net positive suction head for the pump, which is exactly why I did 1/2" suction lines.

I've done all of my fuel flow testing on my newest -10 on the ground. I'll keep you posted.

Yes, all of ours was in the ground but the data showing the pressure loss was during flight. Let us know.

 

[rongawer]

Yes, all of ours was in the ground but the data showing the pressure loss was during flight. Let us know.

I'm really curious what changed with your aircraft on the ground vs in the air. Does your fuel system have serial fuel flow? Such as fuel from one bank of cylinders then flows to the other? I ask because my SDS system supplies to a fuel block which then returns to the tank; the injectors are all fed from that block. If the injectors in sum at full load don't exceed the available fuel load, then you should still have excess pump capacity available at regulated pressure - this is a system design, not an altitude dependent variable and can be calculated from the injector specs. Only if there is a restriction in your system that changes at altitude (i.e. your regulator) would there be a difference between ground and altitude performance.

These rotary pumps operate best closest to the fuel source, hence why nearly all cars have them installed in the fuel tanks. While heat can be a factor, this generally only impacts devices mounted forward of the firewall, which leaves the biggest headloss factor being the suction side of the pump. Increasing the size of the pump power definitely helps provide a greater differential pressure, but it masks the real issue, which I suspect is suction side restriction for the higher power engine.

3/8" lines are fine for the 260 hp target engine of the -10, but I highly recommend anyone intending higher powered engines for their aircraft, any airframe, focus on larger suction lines and making those lines as short and with fewest bends as possible. Ideally with the pumps as near the fuel tank as possible with a goal of short and high volume suction lines, and then longer higher pressure supply lines.

 

[Dustyone]

I always assumed that band clamp was just for the fire sleeve.

Hey Michael,

re: System 32 EFII Injectors

The clamp I was referring to is the one that clamps the alloy body to the blue T fitting.
It may work ok but it is an unusual thing to see in my world.

This is one of the injectors that was removed and the band clamp removed for clarity.

 

[Toobuilder]

This is one of the injectors that was removed and the band clamp removed for clarity.

Copy. Never noticed THAT band clamp before...

Interesting.