Precision? Airflow Performance? FlyEFII? Which injection system?

[Zzz]

For those who've chosen injected Lycoming engines for their Bearhawks, which injection system did you choose? Original Bendix or Precision Airmotive? Airflow Performance? FlyEFII?

The last 2 require return fuel lines while the original design does not. I'm curious if anyone has plumbed theirs for return lines. If you've gone injected Continental I think the same is required.

Not looking for a carbureted vs injected debate, just some additional info on fuel system design for some of these modern injection systems.

Thanks!

[whee]

I'll be following this and looking into the systems with return lines. I want to be able to run mogas so a return line is a good idea to help with vapor lock.

My plan is to run one return line to the left tank. Valving is simple and you always know where the fuel is returning. I recently talked to a guy that did that on his BH and he said it works well.

[Zzz]

I'll be following this and looking into the systems with return lines. I want to be able to run mogas so a return line is a good idea to help with vapor lock.

My plan is to run one return line to the left tank. Valving is simple and you always know where the fuel is returning. I recently talked to a guy that did that on his BH and he said it works well.

One of the known issues is accuracy of fuel flow. You have to have a second transducer on your return line to subtract that volume from the inlet volume. Do the modern fuel flow computers allow for 2 sensor inputs to calc a differential?

[whee]

Can't you put the transducer after the return line? I imagine this is already worked out because of all the planes with injected continentals running fuel computers.

[Battson]

Yes, you can put it downstream of the fuel servo in the smaller diameter line - which is the preferred location to minimize flow restriction.

[Mark Moyle]

On the continental. The line from the throttle body/proportioning valve to the fuel spider is the correct location for a fuel flow transducer. The fuel to and from the injection pump can go roundie roundie without effecting an accurate fuel flow reading.


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[Mark Moyle]

I'll be following this and looking into the systems with return lines. I want to be able to run mogas so a return line is a good idea to help with vapor lock.

My plan is to run one return line to the left tank. Valving is simple and you always know where the fuel is returning. I recently talked to a guy that did that on his BH and he said it works well.

Mine will use right and left header tanks under the floor...haven't built them yet...it'll be a duplication of the Cessna 185 IO520D fuel system. Will use the Andair valve with the 1/2" and 1/4" Delivery/return. The return lines to the wing tanks from the under the floor header tanks also purge air from the system.


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[whee]

Will use the Andair valve with the 1/2" and 1/4" Delivery/return.

I had a dream the other night that a valve like that existed but I'd never seen one a didn't bother looking. Just looked a yep, "duplex" valves exists and seem like a great way to control fuel. Seems like there isn't a need for a header tank if you have a duplex valve.

I was just looking at the FLYEFII system. Not sure how I feel about not having mixture control. They show a pic of a display while running lean of peak...what if you don't want to be running LOP?

[Zzz]

I had a dream the other night that a valve like that existed but I'd never seen one a didn't bother looking. Just looked a yep, "duplex" valves exists and seem like a great way to control fuel. Seems like there isn't a need for a header tank if you have a duplex valve.

I was just looking at the FLYEFII system. Not sure how I feel about not having mixture control. They show a pic of a display while running lean of peak...what if you don't want to be running LOP?

You can still have a mixture control and override it, or so I recall reading.

[Zzz]

http://www.precisionairmotive.com/

Precision makes the Silverhawk injection and also the Eagle EMS electronic injection system. Neither require return lines. Anyone have any experience with these?

[dedgemon]

I'm flying silverhawk on my RV8. Works very well. Simple install with just a fuel line loop from the pump outlet back to the fuel valve. I would go this route again if i wanted FI. Keep the fuel system simple and robust. Errors in fuel delivery can kill you.
Friends who are usinfg the airflow system are happy with it. It is just slightly more trouble to install with the purge valve. Fear of hot hots is misplaced. Its simple to start the non-purge systems hot, you just have to understand that the system is flooded. Hot starts begin cranking with the mixture at idle cutoff. When it hits smoothly advance the mixture.

[Zzz]

I'm flying silverhawk on my RV8. Works very well. Simple install with just a fuel line loop from the pump outlet back to the fuel valve.

Can I just tee-in upstream of the valve?

[dedgemon]

yup thats basically it. The typical install for the silverhawk type is valve, then aux pump then mechanical pump. I use the airflow performance aux pump. It has a pressure regulator an outlet for the return line. There are some other aux pumps out there now you might want to look at also.

[rodsmith]

I'm using an Airflow performance system, it doesn't require a return line. I'm not flying yet but people seem to be very happy with them.

[dedgemon]

The airflow performance is very similar to the silverhawk in plumbing, etc. The major difference is the addition of the purge valve to flush fuel up to the spider and this is also used to kill the fuel instead of using the mixture. apparaently works very well. Don worked for bendix and then designed his own system i beleve. he has been very helpful in provided additionall orifices (orifi?) for my silverhawk in order to balance the mixture

[robcaldwell]

For those who've chosen injected Lycoming engines for their Bearhawks, which injection system did you choose? Original Bendix or Precision Airmotive? Airflow Performance? FlyEFII?

The last 2 require return fuel lines while the original design does not. I'm curious if anyone has plumbed theirs for return lines. If you've gone injected Continental I think the same is required.

Not looking for a carbureted vs injected debate, just some additional info on fuel system design for some of these modern injection systems.

Thanks!

I will be installing a new Lycoming Thunderbolt YIO-540-EXP 9:1 Compression Parallel Valve with Airflow Performance Fuel Injection on my 4-Place. This past Friday I stopped by Airflow Performance in Spartanburg, SC (on my way to the Triple Tree Fly-In in Woodruff, SC) and visited with Don Rivera, the owner. Don and I reviewed the fuel system for my Bearhawk 4-Place and he determined the following... No return lines or modifications are required to the existing fuel system EXCEPT to install a #6 maintainable inline fuel filter (Airflow part #1090079) after the Gascolator (he does not feel the Gascolator is adequate enough) and a Auxiliary Fuel Pump (Airflow part #2090255) aft of the firewall. No header tanks, no sump tanks, no return lines.