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  #131  
Old 06-19-2017, 11:29 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by Chkaharyer99 View Post
That's a really cool feature Ross. I had no idea that option was available. I thought it was all electrical, no mechanical. That makes it more appealing. With
mechanical fuel pump only, what kind of performance could one expect from a lycoming IO360 with 9:1 pistons. Can you sustain flight? Or is it just prolong flight?

If you have documention on this feature, could you please send me the link where I can learn more?

Thanks
Several single ECU SDS users over the years have devised their own mechanical fuel backups. Usually consists of some fixed orifice nozzles mounted in the intake plenum with a manual fuel valve or solenoid valve to turn on and off fuel. This gives you one power setting with a fixed throttle amount to get back over an airport. You'd size nozzles for the hp level you wanted. This is not something we offer or give design advice on.
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Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW- 413.5 hrs. on the Hobbs,
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http://www.sdsefi.com/aircraft.html
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  #132  
Old 06-19-2017, 02:00 PM
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stringfellow stringfellow is offline
 
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Quote:
Originally Posted by rv6ejguy View Post
I'm not sure of the mods done to the pumps, resultant life reduction etc. One is a Sport Class Continental which is a different design than the standard finger drive Lyc pump. I believe the Lyc users have fitted the Lear type rotary pumps.

Plumbing is not really simplified with the mech pump and you still need the bypass regulator to maintain proper differential over MAP for precise metering since pump output exceeds engine usage.

The twin electric pumps have proven to be 100% reliable to date if mounted and filtered as we recommend. The current draw is only a concern if you lose the alternator. We recommend either twin alternators (small vacuum pad one is fine for backup) and/or a backup battery with our EFI systems.
I think the twin alt is the way to go, or use a smaller backup with a load reduction plan for emergency.

In talking with another EFII user who had an alternator failure, even with two batteries, the run time was measured in minutes because of the load of the pumps. I think very prominent annunciation for alternator output drop is a critical thing too.
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  #133  
Old 06-19-2017, 02:16 PM
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Toobuilder Toobuilder is offline
 
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To be fair, the electrical draw is a known value, so if someone has a run time of "minutes", then the batteries were not sized properly to meet requirements. Someone didn't do their homework.

Mine is a VFR airplane and loss of the single alternator is a "land right now" event, despite enough battery capacity to exceed the fuel supply. I know some want enough redundancy to be able to carry on to the destination after a failure, but that's not for me.

There are numerous ways to skin this cat, so it does not surprise me one bit that Ross doesn't want to make a recommendation. But the tools and the methods to make your own determination are out there, and Dan H dragged us through an effective system deconstruction on this very forum recently.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

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  #134  
Old 06-19-2017, 02:27 PM
rv7charlie rv7charlie is offline
 
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Quote:
Originally Posted by stringfellow View Post
I think the twin alt is the way to go, or use a smaller backup with a load reduction plan for emergency.

In talking with another EFII user who had an alternator failure, even with two batteries, the run time was measured in minutes because of the load of the pumps. I think very prominent annunciation for alternator output drop is a critical thing too.
I'm certainly not Ross, but I am installing an engine that will have automotive style injection. I also have had several different 'lives' all related to electronics.

If you're running an electrically dependent engine, there is no good reason to not *know*, within a few minutes, the remaining duration of flight after you lose your electron maker. And there's no good reason to fly a system that can only last 'minutes' (unless that is a significant percentage of an hour) after losing your electron maker.

Know (all) your electrical loads. Know your battery's standby capacity, at required loads (hint: it's never as good as the number on the label). Design so that you can shed loads as required to stay in the air. Test the battery(ies) at reasonable intervals to prove it can still tote the load, for as long as you expect.

Or install a backup electron maker, capable of sourcing enough electrons for your (known) loads.

There's nothing inherently bad (and a lot that's good) about electrically dependent engine control, but if you don't do complete failure analysis, it can drive some bad decisions.
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  #135  
Old 06-19-2017, 02:42 PM
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Go easy guys. I like a dual battery KIS approach to powering ignitions, but we're talking VFR and 1 amp per sparky thingy. Dual alternators make a lot of sense with large pump draws and a heavy panel. It's not so easy to be sure of full battery capacity all the time, every flight, and IFR might not offer an immediate path to the ground.
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  #136  
Old 06-19-2017, 03:17 PM
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rv6ejguy rv6ejguy is offline
 
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All good replies here on backup power. If I was flying IFR, I'd have 2 alternators and 2 batteries. On the other hand, I wouldn't fly IFR/ night VFR in a single piston anyway but that's just me.

On a Lycoming with a free vac pad, I'd probably add a small backup alternator there- so easy to do and downsize the backup battery a bit to offset the weight.

We tell people to figure on about 11-12 amps with dual SDS ignition at cruise rpm on a Lycoming four, about 13-14 on a six for one pump, injectors, ECUs and coil packs.
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Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW- 413.5 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #137  
Old 06-20-2017, 03:08 PM
Chkaharyer99 Chkaharyer99 is offline
 
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Thanks Ross. Sorry if I drifted your thread, but I learned a lot asking those questions.

Looking forward to the next Dave Anders update.
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  #138  
Old 06-20-2017, 09:22 PM
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[quote=rv7charlie;1181394]Mark,

Are you asking about a stock engine driven pump? I don't know of any that will approach the 40+ PSI needed for automotive style injectors.

snip

No, I will get a stock TCM pump changed around to produce the proper pressure (50PSI min) and flow (55GPH min) - similar to what Andy Findlay did for his TSIO-550. I won't need quite the pressure and flow that Andy will as I'm only gonna set up for 50"MP.

One of the usual O/H shops told me they could do a similar pump mod using a Romec type pump (vac pad setup), or the pump used on the TSIO 550 that uses a Bendix fuel system (another Romec type pump that actually fits up to the TCM engine). Of course, the Romec can be affixed to the 540 with a change-out to the aft cover.

If using the Romec style pump, plan to use your boost pump when taking off, or landing and taxiing in.

I am thinking of keeping the mags due to the boosted engine - it's gonna have 30"MP where ever I go. That would allow for an emergency fuel nozzle to be placed at the outlet of the supercharger for the one time the electrons decide to bail out. 8-10GPH ought to do the trick if such is actually possible.

BUT! Those electronic ignitions sure do light off the fuel in a hot start situation...

What could possibly go wrong??!!

Don't worry - I know there are PLENTY of things that could allow me to log some glider time...

Best,
Mark
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  #139  
Old 06-21-2017, 06:39 PM
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Mark: For what it's worth, I'm flying my AF Performance injected, Lycoming 540 on a Romec vane pump that's been "tuned down" to around 28 gph for takeoff. Seems to work well and yes, I run the boost pump on takeoff and in the pattern. I doesn't need the electric pump just taxiing much of the time but in the summer, especially taxiing in, it sometimes won't run smoothly without it.


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