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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2718665@logan.com>
Subject: Hardwire? [FlyRotary] Re: Ignition advance
Date: Thu, 7 Feb 2008 08:40:32 -0500
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Ernest, not familiar with your EFI system.  However, your statement about 
hardwiring it for 20 deg and then using the computer to add advance caught 
my attention - normally that  is not how it is done.  It is difficult for a 
CPU design to "ADD" or advance ignition timing from a static timing point as 
that implies it has to know in advance (precognition but not pre-ignition - 
sorry, couldn't help it)  when the next firing event is coming.  All of the 
EFI units  that I am familiar will  set or "Hardwire" the static timing to 
the maximum amount of ignition timing advance they will ever want.  Then the 
computer is used to retard the timing from that point which is much easier 
to do.  Tracy's EC2 uses this method and that is why his instruction have 
you set the static ignition timing to 31-35 Deg BTDC and then the CPU simply 
backs off to there to the "Advance" you want.

FWIW

Ed
----- Original Message ----- 
From: "Ernest Christley" <echristley@nc.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, February 06, 2008 10:18 PM
Subject: [FlyRotary] Re: Ignition advance


> lehanover@aol.com wrote:
>> Lynn,?
>> ?
>> You've told us that the rotary like about 25 degrees BTDC of advance, and 
>> will run well at most any speed at that setting. Does that include 
>> starting speed? How much will performance be degraded as you back off to 
>> 10 degrees BTDC??
>>
>>
>> For starting, I don,t know if you could tell. But off idle it would be un 
>> responsive, and have high EGTs. It has a very short stroke and very low 
>> torque. If you are worried about over advanced ignition causing a 
>> problem, just do 20 degrees. Once it gets broken in after 5 hours of hard 
>> running, it will start instantly at any setting between 20 and 27 
>> degrees.?
>>
> Perfect!  Absolutely perfect!  I can hardwire it to fire at 20, and then 
> have the computer add in more at speed.
>
> The mount I made for the VR sensors yesterday won't work.  I made it just 
> shy of a 1/4" to short on the left-hand side.  Luckily, I have plenty of 
> aluminum to destroy.
>
> -- 
>
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