After Market Fuel Injection

[aviator79]

While my engine won't have EFI right of of the box, I am buying an overhauled 914 from EDGE, and can add my praise for the level of customer service. They've sent me tons of pictures of the overhaul, and the level of communication is beyond my expectations. When I send an email, I usually hear back within a couple hours. I'm not sure Thomas sleeps.

Now you guys have me thinking about having him add EFI before the engine ships.

[Esser]

DO IT!

Is the 914 overhauled already? Did they weld the crank and upgrade the cam so you can bolt on additionsvas you go?

[aviator79]

It is already overhauled. He's hanging onto it because he's building a new engine test stand that he wants to run it on, and I don't need it right away. I don't believe it has the welded crank. It does have 912ULS cylinders and pistons, for a slight increase in displacement. The EFI would make it about as upgraded as it could be. I think you can have EDGE de-rate from the 154HP advertised for the 912STi engine, and if I did EFI, I would probably have mine de-rated. More is not always better; increased brake mean effective cylinder pressure correlates to reduced longevity and reliability. In other words, there is some risk in drifting too far from the configuration used to establish the TBO.

Also, electrical failures aren't that uncommon, and while a backup battery will probably give you enough juice to make a safe landing, in my part of the continent, it could definitely put you somewhere where making a repair would be very difficult. So I'm kind of on the fence. AirFox's review of the system sure tempts me.

[Esser]

Is it at Jason’s in Canada? Or is it in Norway? I’m going to Jason’s later today

[aviator79]

Is it at Jason’s in Canada? Or is it in Norway? I’m going to Jason’s later today

It is in Norway.

I'm really chewing on this idea a little bit. Is there a failure mode of the regulator that damages the battery? I'm curious about Scott's decision to add a backup battery to protect against a regulator failure. I guess a better question might be, how did you guys design your electrical systems to maximize your time aloft when an alternator or regulator fails, and what types of potential failures motivated those decisions?

[Esser]

I could have went more extreme on my electrical system redundancy however I feel very comfortable with how mine is set up. I have one battery and two alternators. The internal Rotax alt and a 40A external.

The only time the the 18A runs is on a shut down check to make sure it is indeed workin in case I need it next flight. I have a long winded reason for doing it this way that I can share if you’re interested(ie why I don’t check it preflight and why I don’t run with both on). Not everyone agrees with my theory. Most people just run with both alternators on.

The chance of having a dual alternator failure and 45 minutes of battery not being enough to get me to an airport seems very slim in my books.

[Ronin]

Carbs or FI? No contest, go for the FI.

[AirFox]

My backup battery is to run emergency items automatically if Either the regulator or main battery fails. I have had regulators fail. If my regulator fails with EFI then I have to have enough battery to run the ECU and Fuel pump. I installed two EarthX batteries that will keep me in the air. Josh's solution to add the external alternator also works. I keep a spare regulator in the plane in case mine fails.

Scott

It is in Norway.

I'm really chewing on this idea a little bit. Is there a failure mode of the regulator that damages the battery? I'm curious about Scott's decision to add a backup battery to protect against a regulator failure. I guess a better question might be, how did you guys design your electrical systems to maximize your time aloft when an alternator or regulator fails, and what types of potential failures motivated those decisions?

[aviator79]

Is the secondary battery just wired in parallel with your main battery, or do you have it isolated somehow? The alternator seems the preferred approach, but I think that external alternator is a $1500 bit of kit.

[AirFox]

The extra battery is isolated from the main bus on the EXPBus that I used for circuit protection. If the Regulator or main battery fails then I turn off the master and turn on the Backup Battery circuit. Only essential equipment will operate. If only the Regulator fails then I pull the Regulator breaker and can run everything off both batteries.