For the Corvair crowd, I think you'll find that they have a mechanical advance set up. While that's not ideal, and doesn't necessarily fit all situations, it works reasonably well.
Aircraft engines are typically configured to prevent detonation under the worst circumstances; hot engine, marginally lean mixture, hot day, and sea level/ high manifold pressure situations. That's why the O-200s have the timing set at 28 BTDC (24 BTDC with old style cylinders) or most Lycomings are set at 25 BTDC. For both the Corvair mechanical advance and the fixed timing magnetos, they are configured to prevent detonation under the worst case scenario. Aircraft engines, whether they are Corvair, VW, Continental or Lycoming are essentially a one speed engine with the exception of starting and idle. With the Emags, Light Speed Ignition, and a few other aftermarket magneto replacements, the electronics sense both rpm and manifold pressure and use that to calculate timing advance on a timing curve. Emags are designed for the Lycoming engines and advance up to 38 BTDC with low manifold pressure (like under cruise conditions). Light Speed goes up to 41 BTDC with the right combination of RPM and MP. This may provide a marginal increase in power witha tiny bit more timing advance under full throttle conditions, but the beauty of them is the extra advance that kicks in when the manifold pressure drops, like in low throttle or high altitude cruise operation. Under those circumstances, the extra advance can save significant amounts of fuel as the extra timing advance gives a better burn without the danger of detonation under low power operation. -Jeff Scott Los Alamos, NM ----- Original Message ----- From: Craig Williams Sent: 06/09/11 09:43 AM To: KRnet Subject: Re: KR> Combustion process Very good read! Does this mean we need is an advance/retard control in the cockpit in addition to the mixture control? Craig www.kr2seafury.com --- On Thu, 6/9/11, Paul & Karen Smith <pk.sm...@bigpond.net.au> wrote: > From: Paul & Karen Smith <pk.sm...@bigpond.net.au> > Subject: KR> Combustion process > To: "KRnet" <kr...@mylist.net> > Date: Thursday, June 9, 2011, 1:27 AM > A good read... > > http://www.innovatemotorsports.com/resources/myths.php > > Paul Smith > Brisbane, AUSTRALIA > pk.sm...@bigpond.net.au > http://kr2spacemodulator.blogspot.com/ > > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
