REFLECTOR: EI and Detonation

Mon Jun 25 10:20:34 CDT 2012

Good to know Mark. 

Yet another reason Im am glad to have a water cooled engine.. .Onward...

Kurt 

-----Original Message-----
From: Mark Magee <edjonesbrady at gmail.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Cc: reflector <reflector at tvbf.org>
Sent: Mon, Jun 25, 2012 9:18 am
Subject: Re: REFLECTOR: EI and Detonation

Hi Kurt,
Klaus said that a knock sensor will not work on an air cooled engine: period. This was seconded by PMAG and Electro Air. Apparently aircooled engines are just tremendously mechanically noisy. Knock sensors 'listen' for a knock and with current automotive style knock sensors (from h2o cooled engines) they can't distinguish between a preignition knock and all the other mechanical noises it 'hears'. GAMI is pioneering technology that reads combustion pressures rather than listening for a knock in sensing pre-ignition. They are working on a FADEC system that the new knock sensor technology is key to. I'm inclined to continue leaning and forgo EI on N34XL until it is clear that a workable FADEC is or isn't  coming. The lack of a knock sensor on current EI offerings is a serious drawback IMHO. Particularly in light of coming changes in 100LL.

Mark B. Magee
N34XL

Sent from IPhone 4

On Jun 25, 2012, at 9:13 AM, nmflyer1 at aol.com wrote:

Mark, 

Good question :)  I haven't flown with it yet or even adjusted it (since I don't have the prop on yet). Klaus has lots of experience, if he is talking about the Stand Alone knock sensors (versus the ones computers use) I would believe him. Mine is adjustable. You set the amount of sensitivity where you want it and go from there. 

Kurt 

-----Original Message-----
From: Mark Magee <edjonesbrady at gmail.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Cc: reflector <reflector at tvbf.org>
Sent: Sun, Jun 24, 2012 10:14 am
Subject: Re: REFLECTOR: EI and Detonation

Hi Kurt,
Do you think it is working (correctly). I've spoken to Klaus Savier at Lightspeed and he said conventional knock sensors won't work due to high engine 'noise' of an air cooled engine. Please elaborate on your findings.
FWIW I understand GAMI is testing a FADEC system that I corporates EI, EFI, ECU and new knock sensor technology that works on noisy air cooled engines. I have a call in to GAMI and will report what they allow on this. Unfortunately for us GAMI will seek certification and therefore cost more and take longer for release.

Mark B. Magee
N34XL

Sent from IPhone 4

On Jun 24, 2012, at 10:01 AM, nmflyer1 at aol.com wrote:

I purchased a Stand alone detonation detector (knock sensor) from Summitt racing. I took it apart and put the display unit on the panel, and the sendor and shriek warning in the kick panel. 

Kurt 

-----Original Message-----
From: John Dibble <aminetech at bluefrog.com>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Sat, Jun 23, 2012 7:31 am
Subject: REFLECTOR: EI and Detonation

              Sorry, I'll try to avoid the send key until finished.

    On 6/23/2012 7:50 AM, John Dibble wrote:    
            Mark,

      Don't know where to begin.  The problem is that over 900 hours, I      didn't know for sure I was detonating until I discovered one      cylinder liner and piston were eaten away at the top.  There were      subtle hints, like when the #5 cylinder temp increased by 50 C      during descent from 9500' with power near idle.  Going full rich      brought the temp down.  Or when the #1 cylinder EI plug gap would      become filled solid with a dark material.  In the beginning I      assumed that was carbon, but later figured out it was metal,      usually steel.  The real attention getter was when the engine      would stumble at 1000' right after T/O.  There's more, but let's      move on to the contributing factors.

      First of all my engine is a 10.5/1 compression Franklin.  I think      the high compression engines simply do not need (or can tolerate)      as much advance.

      Second, at the peak of detonation problems, I discovered the EI      had a bad ground ( 1 ohm of resistance) and I understand that a      bad ground will cause an EI to further advance by 10-20 degrees.       Now I check the ground at every annual.

      Third,  there is no good way to verify that the EI is set up      properly.  It's like dead reconing, you set everything per the      instructions and assume that the timing is where it's supposed to      be.  Well, mine wasn't.  I ended up retarding the timing by about      12 degrees from the instructions.  To preserve the 0 degree      starting capability, I retarded the timing by moving the timing      ring rather than an adjustment to the initial advance setting.  I      determined the desired timing by doing a "mag check" while flying,      making several adjustments on the gound until I achieved the same      rpm drop with the EI compared to the mag.  I have disabled the      manifold pressure advance function and use the minimum 6 degree      rpm advance setting.  Perhaps I could see some performance      increase by using a little more advance at high altitude, but for      now I will keep it simple as avoiding detonation is the prime      consideration.  If I do decide to try more advance in the future,      I will install a rheostat and manually input the extra advance,      but it will be a guess as to how much, so I will probably not try      it.

    John

      On 6/22/2012 10:48 PM, Mark Magee wrote:      

Hi John,

Your issues with detonation are troubling me. I ran a Rose          EI on a Long EZ years ago and know that at 11,500 I was 41DEG          advanced with a reduced fuel burn of about 15%. We in the San          Diego EZ squadron designed the advance curve and Rose burned          it in. 

How did you find out you were detonating?

Detonation could lead us back to our Glide Distance thread.          I don't believe there are any working knock sensors out the          for a LYC/CONT EI, yet it seems to me that retarding back to          mag advance will kill the fuel savings advantage of an EI.

I'd appreciate any additional data on EI advance curve and          detonation you've uncovered

          Mark B. Magee

N34 XL

Sent from IPhone 4

          On Jun 22, 2012, at 8:39 PM, John Dibble <aminetech at bluefrog.com>          wrote:

 Cruise altitude depends on the          weather.  On a rare SKC day I fly 9500/10500.  On a partly          cloudy day, there are bound to be cloud tops to 13000,          requiring O2 if you want to stay above the cloud bases where          the air is far smoother.   When solid overcast, it's usually          smooth air below the ceiling.
          I'd go with the lesser advance timing, or even no advance at          all until you determine how much advance is right for your          engine.  I have one Rose EI on my Franklin and I had          detonation damage from too much advance.  I ended up disabling          the advance and setting the EI to the same advance as my mag.

          John

          On 6/22/2012 6:23 PM, Richard J. Gentil wrote:          

I am planning on taking my first long trip in my Normally Aspirated, Dual EI, MT, IO-390, SERG. Going from Naples, FL to Norfolk, NE. (Day VFR. Not ready to test her in IFR yet.)

I figure I can make it with one stop to stretch the legs and relieve the bladder. 

My question is cruising altitudes. (I can take an O2 bottle if there is any good gain by going up 16,500 or 17,500). 

What altitudes do you find most efficient etc for a Velo. 

I have two timing advance curves with my E-Mag and P-Mag. I am currently using curve A as set by the factory not tried curve B yet. (I have not hooked them up at an EICAD yet.)

I would be very interested in your recommendations. 

Richard

Sent from my iPhone 4 Classic

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