REFLECTOR: EI and Detonation

Brian Michalk michalk at awpi.com
Mon Jun 25 10:46:47 CDT 2012


Yeah, I've researched this a bit.

Sonic detection.  It may not work across multiple engines, but if a 
person were so inclined, I find it hard to believe that the ping could 
not be detected on a per-engine basis.  Of course doing this may require 
more instrumentation than the effort is worth, not to mention 
intentional detonation to define the event.

Cylinder pressure readings.  I believe GAMI has researched ionic 
pressure sensing, which would be way cool and robust.


On 6/25/2012 10:16 AM, Mark Magee wrote:
> 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 
> <mailto: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 <mailto:edjonesbrady at gmail.com>>
>> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org 
>> <mailto:reflector at tvbf.org>>
>> Cc: reflector <reflector at tvbf.org <mailto: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 
>> <mailto: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 
>>> <mailto:aminetech at bluefrog.com>>
>>> To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org 
>>> <mailto: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 
>>>>> <mailto: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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>>>>
>>>>
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