REFLECTOR: engine tuning ... was Project Updates
Brian Michalk
michalk at awpi.com
Sun Jul 1 14:11:03 CDT 2007
My primary system is an Autronic SMC, which fires the spark plugs and
injectors.
The backup system is a hand rolled system. I'm running 45PSI of fuel
pressure which goes to a metering barrel valve. From there it runs to
six injectors which are constant flow "misting nozzles" from McMaster
Carr. The barrel valve is actuated with a stepper motor which is in
turn connected to the ECU with it's own 10AH battery backup ... about
the size of your fist. Running on backup should get me more than 10
hours of flight time.
I designed the ECU circuit board, and wrote the software for it. It
also reports engine parameters to a cockpit display. When designing it,
I was going for maximum battery efficiency and reliable redundancy,
which sacrificed some performance. There are easier ways to do this,
but I wasn't comfortable with many of the failure modes. If the backup
system loses power, while flowing fuel, then the engine will continue to
run. The last fuel flow setting would be active, so the pilot would
have throttle control to richen or lean the engine.
I do not know yet what the final capabilities are going to be, but after
yesterday's run, I think this system could be used as a primary
injection system with no problems. I might have some issues with
atomization at the lower RPM's.
The parts unique to the backup system have not cost a lot of money.
Discounting the pump and fuel pressure regulator, I have about $100 in
injectors, plus maybe another $200 in hoses and fittings. I've put in
lots of hours into machining the barrel valve and manifold, and the
electronics. I don't even want to think about it. It's cost me a year
easily in getting the airplane in the air. It's such a simple system
... to think it required this much effort is amazing.
Alex Balic wrote:
> Hi Brian-
> Can you please give me the spec on your ECU- I am Running a DTA P-8 Pro-
> problem is that it isn't yet actually "Running" so I may need a back up
> plan......
>
> Thanks,
>
> Alex
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Brian Michalk
> Sent: Saturday, June 30, 2007 11:08 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: engine tuning ... was Project Updates
>
> I got a lot of time in on the engine today.
> It just so turns out that the default settings on the Autronic happen to
> turn out to be safely rich of peak. There is a page that you enter all
> of the engine data and it generates a default table.
>
> It wasn't clear in my email, but yeah, I am going to fly first all ROP,
> then work on the LOP.
>
> The backup fuel injection system worked pretty well also. It needs to
> be trimmed a little more to reach full fuel flow. It did get up to
> 1500RPM static. I think 2000 RPM static is attainable.
>
> Wideband O2 would make setting this up a snap.
>
> It was a productive day, and with these results, we are planning to move
> the plane out to the airport.
>
>
> nmflyer1 at aol.com wrote:
>
>>Brian,
>>
>>I waited til this afternoon to respond for a couple reasons,
>>
>>I don't know enough about your system to give very good input so I
>>talked with a work bud of mine. He is pretty good at this electronic
>>tuning stuff and I printed and showed him your post.
>>
>>Having EGT's on all cylinders is very advantageous to your tuning and
>>mapping. As long as you are absolutely sure that the EGT probes are
>>measuring correctly! I'm sure you already checked that... but I thought
>>I'd mention it.
>>
>>Since I don't know your system, I'll let you know that we discussed the
>>table settings using EGT's (similar to a wide band O-2 sensor in
>>practice) and a MAP sensor. Fuel flow added to this and you should have
>>everything you need.
>>
>>One caution; it is warned very strongly not to run LOP in a turbo
>>installation. That advice is for boost applications because detonation
>>is very probably if the flows are cut down, specially in a load
>>situation (not sure if it still applies to "normalization") . I'd be
>>careful picking a RPM range alone for a LOP setting because you may end
>>up getting there accidentally on a climbout. If you are set on getting
>>to LOP, then you may want to include a MAP limit as well.
>>
>>We thought that it may be best to set everything up ROP for now, just to
>>be safe, and see how it all worked. Once you have your data, you can
>>tweak things up later. \
>>
>>Probably not much help, but all I can give with what I know.
>>
>>Kurt
>>
>>
>>-----Original Message-----
>>From: Brian Michalk <michalk at awpi.com>
>>To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
>>Sent: Sat, 30 Jun 2007 10:29 am
>>Subject: REFLECTOR: engine tuning ... was Project Updates
>>
>>Kurt,
>>
>>I'm still trying to tune in my engine as well. I've never tuned an
>>engine with electronics so this is new to me. I had been messing around
>>with the flow table, jiggling a little here and there, and determined
>>that my #4 injector was not flowing correctly. I now have a new #4, and
>>am going to tune again today.
>>
>>I have half a mind to set the tables back to default and start over. My
>>plan is this:
>>1) Use average EGT (turbine inlet temperature) to find the peak and
>>50ROP for at least two, hopefully three cells on the table.
>>2) Now go back to the data for individual EGT's and trim those values to
>>get them to peak at the same time. I have one bulk table, and six
>>individual tables. The per-cylinder tables can go from 40% to 160%
>>range of what's in the bulk table.
>>
>>Is there a better methodology I'm not aware of?
>>
>>Once I am more comfortable with the operating fuel flows, I am going to
>>mark out an area on the fuel table for running lean of peak. Perhaps
>>the area defined by RPM greater than 2500, and manifold pressure less
>>than 27 inches. I'll have to collect more data to see where this area
>>should be.
>>
>>My backup EFI still needs tweaking. The good news is that the engine
>>does run on my completely homebrew setup. I'm trimming my spool for the
>>barrel valve and will see how that works today.
>>
>>
>>NMFlyer1 at aol.com <mailto:NMFlyer1 at aol.com> wrote:
>>...
>>
>>
>>>
>>>I ran the engine again yesterday and all seems well. Now IM on to
>>>cutting some exit ports in the cowl.
>>>
>>>Keep us informed,
>>>
>>>Kurt
>>
>>_______________________________________________
>>To change your email address, visit
>
> http://www.tvbf.org/mailman/listinfo/reflector
>
>>Visit the gallery! www.tvbf.org/gallery <http://www.tvbf.org/gallery>
>>user:pw = tvbf:jamaicangoose
>>Check new archives: www.tvbf.org/pipermail <http://www.tvbf.org/pipermail>
>>Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>>
>>------------------------------------------------------------------------
>>AOL now offers free email to everyone. Find out more about what's free
>>from AOL at *AOL.com* <http://www.aol.com?ncid=AOLAOF00020000000437>.
>>
>>
>>------------------------------------------------------------------------
>>
>>_______________________________________________
>>To change your email address, visit
>
> http://www.tvbf.org/mailman/listinfo/reflector
>
>>Visit the gallery! www.tvbf.org/gallery
>>user:pw = tvbf:jamaicangoose
>>Check new archives: www.tvbf.org/pipermail
>>Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
> _______________________________________________
> To change your email address, visit
> http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery! www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
>
> _______________________________________________
> To change your email address, visit http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery! www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
More information about the Reflector
mailing list