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Date: Thu, 17 Nov 2011 11:44:03 -0500
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From: Gary Casey <casey.gary@yahoo.com>
Reply-To: Gary Casey <casey.gary@yahoo.com>
Subject: Re: E-Mag/P-Mag
In-Reply-To: <listdigest-5203449@logan.com>
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It all depends on the spark advance schedule built into the units, and I do=
n't know much about the p-mag. =A0I'm told that at high altitude cruise (lo=
w manifold pressures) the Lightspeed will advance the spark by at least 7 d=
egrees over the base timing. =A0That should (will) give a substantial perfo=
rmance benefit at altitude. =A0Low-elevation takeoffs won't be any differen=
t because there is no spark advance change over a standard mag. =A0All I ca=
n tell is that my non-turbocharged ES will degrade significantly less than =
a normal plane as the altitude goes up. =A0It is very happy above 12,000 fe=
et and still has good performance at 17,000. =A0Some say 10 to 20 percent, =
but I'm not sure I buy that. =A0"Up to 10 percent", as the ads say, is cert=
ainly believable. =A0If you fly a lot above 12,000 feet having a system tha=
t advances the timing is well worth it, in my opinion. =A0If you routinely =
fly at 3,000 feet throttled back to less than 20 inches manifold pressure y=
ou
 probably wouldn't be subscribed to the Lancair list :-)=0A=0AOn the other =
hand, I wouldn't go to the trouble for a turbocharged engine, as the engine=
 will never - or rarely - operate at low manifold pressure for any length o=
f time. =A0The only operational problem with a mag is potential cross-firin=
g at high altitude, high boost conditions. =A0So for that reason you might =
want a distributorless system(Lightspeed, e-mag, p-mag or whatever), I don'=
t know.=0A=0AAgain, the important thing is not so much about how the spark =
is formed, but WHEN it fires. =A0Regarding the question from Scott about ef=
ficiency or performance - the engine always inhales the same amount of air =
and fuel, so the spark advance just increases the power derived - which is =
the same as efficiency. =A0More power on the same fuel. =A0The difference i=
s greater as the engine is run leaner of peak as well as at high altitude. =
=A0Both slow the burn rate, so more advance is welcome.=0A=0AThese comments=
 apply to any open-loop system. =A0Adaptive systems, such as the PRISM, are=
 a different story.=0AGary Casey=0A=0A=0A=0A=A0For those using the p-mag.=
=A0 Is there any significant increase in fuel efficiency or=0Aincrease in p=
erformance noticed?=0A=A0=0AThanks=0AScott Keighan
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:bo=
okman old style, new york, times, serif;font-size:12pt"><div>It all depends=
 on the spark advance schedule built into the units, and I don't know much =
about the p-mag. &nbsp;I'm told that at high altitude cruise (low manifold =
pressures) the Lightspeed will advance the spark by at least 7 degrees over=
 the base timing. &nbsp;That should (will) give a substantial performance b=
enefit at altitude. &nbsp;Low-elevation takeoffs won't be any different bec=
ause there is no spark advance change over a standard mag. &nbsp;All I can =
tell is that my non-turbocharged ES will degrade significantly less than a =
normal plane as the altitude goes up. &nbsp;It is very happy above 12,000 f=
eet and still has good performance at 17,000. &nbsp;Some say 10 to 20 perce=
nt, but I'm not sure I buy that. &nbsp;"Up to 10 percent", as the ads say, =
is certainly believable. &nbsp;If you fly a lot above 12,000 feet
 having a system that advances the timing is well worth it, in my opinion. =
&nbsp;If you routinely fly at 3,000 feet throttled back to less than 20 inc=
hes manifold pressure you probably wouldn't be subscribed to the Lancair li=
st :-)</div><div><br></div><div>On the other hand, I wouldn't go to the tro=
uble for a turbocharged engine, as the engine will never - or rarely - oper=
ate at low manifold pressure for any length of time. &nbsp;The only operati=
onal problem with a mag is potential cross-firing at high altitude, high bo=
ost conditions. &nbsp;So for that reason you might want a distributorless s=
ystem(Lightspeed, e-mag, p-mag or whatever), I don't know.</div><div><br></=
div><div>Again, the important thing is not so much about how the spark is f=
ormed, but WHEN it fires. &nbsp;Regarding the question from Scott about eff=
iciency or performance - the engine always inhales the same amount of air a=
nd fuel, so the spark advance just increases the power derived -
 which is the same as efficiency. &nbsp;More power on the same fuel. &nbsp;=
The difference is greater as the engine is run leaner of peak as well as at=
 high altitude. &nbsp;Both slow the burn rate, so more advance is welcome.<=
/div><div><br></div><div>These comments apply to any open-loop system. &nbs=
p;Adaptive systems, such as the PRISM, are a different story.</div><div>Gar=
y Casey</div><div><span class=3D"Apple-style-span" style=3D"color: rgb(69, =
69, 69); font-family: arial, helvetica, sans-serif; font-size: 13px; "><div=
 class=3D"inlinemsgheader"><br></div><div id=3D"yiv1024262784"><div><div di=
r=3D"ltr"><br>&nbsp;For those using the p-mag.&nbsp; Is there any significa=
nt increase in fuel efficiency or<br>increase in performance noticed?<br>&n=
bsp;<br>Thanks<br>Scott Keighan</div></div></div></span></div></div></body>=
</html>
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