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07-12-2011, 07:30 AM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Quote:
Originally Posted by G3i Ignition
I totally agree with advancing a single spark system on the lower MAP. However, light the air/fuel mixture with multiple sparks, the same amount of btu’s produced will happen in a shorter window of time. Basically, light a piece of paper on one corner, x-amount of time to burn completely. Now light all 4 corners, a complete burn in a much shorter time period. With the same amount of btu’s produced. Another perfect example of flame propagation is when a (L/R) mag drop is performed. Its not because the ignition system is weak, just poor flame travel at peak cylinder pressure at that rpm and low MAP. These are some of the topics that I will be discussing @ AirVenture 2011. Hope to see ya there.
Thomas S.
AirVenture Presenter 07/26/11
http://www.eaaapps.org/presenterinfo.aspx?id=1470
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This is a good theory except that spark plugs are fixed in the combustion chambers so kernel initiation points are also fixed. You can't light 4 corners so to speak from one or two points and on mutiple spark systems, any sparks after the initial ones are late as well.
Not to pick on anyone here but the merits of CDI vs. inductive discharge vs. multispark CDI as applied to conventional, slow turning atmo aircraft engines is pretty much a moot point. These engines have relatively low spark energy needs due to the low cylinder pressure they operate at. All the systems out there will work about the same from that viewpoint, the timing curves are far more important.
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07-12-2011, 12:25 PM
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Join Date: Aug 2009
Location: Littleton, Colorado
Posts: 182
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Quote:
Originally Posted by rv6ejguy
This is a good theory except that spark plugs are fixed in the combustion chambers so kernel initiation points are also fixed. You can't light 4 corners so to speak from one or two points and on mutiple spark systems, any sparks after the initial ones are late as well.
Not to pick on anyone here but the merits of CDI vs. inductive discharge vs. multispark CDI as applied to conventional, slow turning atmo aircraft engines is pretty much a moot point. These engines have relatively low spark energy needs due to the low cylinder pressure they operate at. All the systems out there will work about the same from that viewpoint, the timing curves are far more important.
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Off topic a little bit,
A basic point about cylinder filling. When the air/fuel charge enters into the cylinder a swirl pattern takes place. On my SuperFlow bench I have a swirl meter that is located at the base of the cylinder and reads the RPM of the swirl vortex. The vortex RPM is direct proportional to intake valve lift. I have seen numbers upward of the 2500 RPM range. So where the multiple spark comes into play, the multiple spark is still exposed to un-burned air/fuel mixture, the analogy is that the paper is spinning at high rate exposing combustible material at different points to the fixed location of ignition. This is great stuff, I love it.
Thomas S.
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07-12-2011, 12:52 PM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Quote:
Originally Posted by G3i Ignition
Off topic a little bit,
A basic point about cylinder filling. When the air/fuel charge enters into the cylinder a swirl pattern takes place. On my SuperFlow bench I have a swirl meter that is located at the base of the cylinder and reads the RPM of the swirl vortex. The vortex RPM is direct proportional to intake valve lift. I have seen numbers upward of the 2500 RPM range. So where the multiple spark comes into play, the multiple spark is still exposed to un-burned air/fuel mixture, the analogy is that the paper is spinning at high rate exposing combustible material at different points to the fixed location of ignition. This is great stuff, I love it.
Thomas S.
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Hard to draw conclusions from a flow bench especially a dry bench like the Superflow as it relates to charge stratification in an actual engine. The valves are closed when the spark happens in any case and several milliseconds pass from piston BDC to near TDC when the spark takes place. The piston movement has a large effect on turbulence and mixing. Some top engine builders use wet benches to better visualize mixture flow and always validate theory through dyno testing.
I've run flow benches for many years and dynos as well. Have yet to see a power improvement with multi spark systems on run of the mill engines. Using inductive discharge ignitions we only see issues with igniting very dense charges on highly boosted race engines operating at specific outputs well in excess of 200hp/L (a 1200hp 360 Lycoming for comparison).
It would be most interesting to take all the EIs on the market today and dyno them with identical timing curves on the same engine. My guess is that you'd see no more variation than experimental error though.
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07-25-2011, 06:21 AM
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Join Date: Aug 2009
Location: Littleton, Colorado
Posts: 182
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Ignition talk @ KOSH
On the field today & tomorrow surfing around. Any EI topics / question you would like to personally talk about, Best contact is my cell 303-906-6846 and will be over @ Russ?s Supercharged 7 off and on through out the day. Front row over in the RV parking
Thomas Shpakow
AirVenture Presenter 07/26/11
http://www.eaaapps.org/presenterinfo.aspx?id=1470
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07-26-2011, 04:53 AM
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Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
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Quote:
Originally Posted by G3i Ignition
Off topic a little bit,
A basic point about cylinder filling. When the air/fuel charge enters into the cylinder a swirl pattern takes place. On my SuperFlow bench I have a swirl meter that is located at the base of the cylinder and reads the RPM of the swirl vortex. The vortex RPM is direct proportional to intake valve lift. I have seen numbers upward of the 2500 RPM range. So where the multiple spark comes into play, the multiple spark is still exposed to un-burned air/fuel mixture, the analogy is that the paper is spinning at high rate exposing combustible material at different points to the fixed location of ignition. This is great stuff, I love it.
Thomas S.
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The 2500 rpm swirl bolsters Russ's point I think. At that rate, the swirl would turn 90 degrees during the whole expansion stroke. Ignition is a mere fraction of that stroke timing so the fresh mixture movement over the plugs would me minimal.
__________________
Bill Pendergrass
ME/AE '82
RV-7A: Flying since April 15, 2012. 850 hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'... Eyeballin' vinyl really hard.
Yeah. The boss got a Silhouette Cameo 4 Xmas 2019.
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07-26-2011, 11:13 AM
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Join Date: Nov 2005
Location: KRTS
Posts: 1,798
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You guys make my brain hurt!
Went with one PMAG and one Slick mag. Look at maybe going all EI in the future if there's a good reason.
__________________
Next?, TBD
IAR-823, SOLD
RV-8, SOLD
RV-7, SOLD
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08-09-2011, 08:52 AM
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Join Date: Jan 2010
Location: PAWS (Wasilla, Alaska)
Posts: 136
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EI
I have always questioned the installation of standard mags (slick, Bendix) next to an EI for "safety" or "backup". Standard mags have a proven reliable life of 500 hrs. after that you are being a test pilot. Now it is a very solid 500 hrs vs an EI that runs a really really long time but we dont know when it might fail. So I would run two EI's with the odds of failure super low, and the odds of a double failure being almost never. Now I would recomend 2 Pmags, or an independant backup ignition power supply for other EI models requiring external power, so that I had 2 compleat stand-alone ignition systems. I have see enough single mag failures not to want them as my backup. My .02 Russ
__________________
Russell Brown
A&P/IA
"Happiness may never be sensibly pursued as an end in itself, because happiness is the by-product of achievement." -- Northcote Parkinson (paraphrase)
Wasilla, Alaska
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08-09-2011, 12:49 PM
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Join Date: Jan 2008
Location: Upland, CA
Posts: 286
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EFII ignition
We have competitively priced ignitions in both single mag replacement and dual mag replacement versions. Our systems can also be upgraded to complete electronic engine management with electronic fuel injection. Our systems utilize a sturdy billet crank trigger that does not require engine case modification for installation and include Iridium spark plugs, spark plug adapters, plug wires, and a durable Tefzel wiring harness with weather sealed connectors.
Our systems feature a high energy inductive ignition much like what you will find on any modern car and are fully programmable.
More details can be viewed here:
http://www.flyefii.com/
If you have additional questions or are interested in a system, please email me directly at:
robert@protekperformance.com
Robert Paisley
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08-09-2011, 12:56 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Robert, any plans to take care of us 6 cyl folks?
Your web site only shows systems for the 4 cyl engines.
Thanks,
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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08-09-2011, 01:34 PM
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Join Date: Jan 2008
Location: Upland, CA
Posts: 286
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EFII ignition for six cylinder
Hi Mike,
Yes we can do six cyl ignitions using three coil packs.
Next year we will have a version of the six cyl ignition that has two six outlet coil packs.
Robert
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