Dual fire ignition coil
Seasoned HDF Member
Joined: Jul 2014
Posts: 8,610
Likes: 3,377
From: Cental, MI
Just to muddy things up. LOL. There is a theory that in a spark plug, because the center electrode runs hotter in a combustion chamber than the shell electrode, and electron flow has better flow characteristics from hot to cold, that polarity wiring to a coil does make a difference. Moot point for a harley dual fire coil. However, in some early automotive applications, the coil is polarity sensitive because of the coil's internal wiring. Back in the old days of vacuum tubes, the cathode portion of vacuum tubes were heated to have thermionic emission of electrons. When you get a hotter running plug, your basically getting a plug that the center electrode runs hotter. ??
Who is Correct??? or Who is Backwards??? Do we really Know????
But, it is true, that certain metals, when heated, more readily Give Up Electrons..
Cruiser
Joined: May 2020
Posts: 117
Likes: 44
From: Corrales NM
I know that some believe that positioning the electrode with thin washers to rotate to a better place for the spark. In my mind there is a fire fight in a combustion chamber and my bet is repositioning an electrode is wasted thinking. I have told some that believe this that I'd have to see it on the dyno.
The biggest improvement in combustion in low and mid` range is creating a vortex. Hemi's not so much but they do well flat out.
The problem with the spark plug theory is it grounds the coil. DC behaves differently from AC especially where grounds are involved.
Once the coil is saturated the spark follows the wire. The spark isn't going to go backwards.
While a bit off the post I once had a hot rod with an ignition that had two coils, two sets of points. 2 rotor contacts.Each set fired 4 of the 8 cylinders. The idea was more time for coil saturation = hotter spark.
Coil saturation used to be a problem before the design of each cylinder having it's own coil.
The biggest improvement in combustion in low and mid` range is creating a vortex. Hemi's not so much but they do well flat out.
The problem with the spark plug theory is it grounds the coil. DC behaves differently from AC especially where grounds are involved.
Once the coil is saturated the spark follows the wire. The spark isn't going to go backwards.
While a bit off the post I once had a hot rod with an ignition that had two coils, two sets of points. 2 rotor contacts.Each set fired 4 of the 8 cylinders. The idea was more time for coil saturation = hotter spark.
Coil saturation used to be a problem before the design of each cylinder having it's own coil.
Seasoned HDF Member
Joined: Jul 2014
Posts: 8,610
Likes: 3,377
From: Cental, MI
I know that some believe that positioning the electrode with thin washers to rotate to a better place for the spark. In my mind there is a fire fight in a combustion chamber and my bet is repositioning an electrode is wasted thinking. I have told some that believe this that I'd have to see it on the dyno.
The biggest improvement in combustion in low and mid` range is creating a vortex. Hemi's not so much but they do well flat out.
The problem with the spark plug theory is it grounds the coil. DC behaves differently from AC especially where grounds are involved.
Once the coil is saturated the spark follows the wire. The spark isn't going to go backwards.
While a bit off the post I once had a hot rod with an ignition that had two coils, two sets of points. 2 rotor contacts.Each set fired 4 of the 8 cylinders. The idea was more time for coil saturation = hotter spark.
Coil saturation used to be a problem before the design of each cylinder having it's own coil.
The biggest improvement in combustion in low and mid` range is creating a vortex. Hemi's not so much but they do well flat out.
The problem with the spark plug theory is it grounds the coil. DC behaves differently from AC especially where grounds are involved.
Once the coil is saturated the spark follows the wire. The spark isn't going to go backwards.
While a bit off the post I once had a hot rod with an ignition that had two coils, two sets of points. 2 rotor contacts.Each set fired 4 of the 8 cylinders. The idea was more time for coil saturation = hotter spark.
Coil saturation used to be a problem before the design of each cylinder having it's own coil.
and Single Fire...is also beneficial...not for saturation time...as if that was anything how could MSD function... [also a benefit BTW]
Single fire is Singularly Beneficial with Dual Plugs and high compression applications..especially with any even close to Hemi design..
As an aside... Back in the day we could make Unlimited HP and get a jillion miles to the Gallon, If we applied all of the Hyped up BS available in the JC Whitney catalog... Lots of "Stuff" out there is designed Specifically to appeal to the Consumer and their gullibility..
Proof is something that one needs to go get for yerself..
When yer searching for tenths of a second, you can get desperate, and try crazy things...
Cruiser
Joined: May 2020
Posts: 117
Likes: 44
From: Corrales NM
Actually "Indexing" plugs is Beneficial.. BTDT... no Dyno tho ...1/4 mile ET is all I want..
and Single Fire...is also beneficial...not for saturation time...as if that was anything how could MSD function... [also a benefit BTW]
Single fire is Singularly Beneficial with Dual Plugs and high compression applications..especially with any even close to Hemi design..
As an aside... Back in the day we could make Unlimited HP and get a jillion miles to the Gallon, If we applied all of the Hyped up BS available in the JC Whitney catalog... Lots of "Stuff" out there is designed Specifically to appeal to the Consumer and their gullibility..
Proof is something that one needs to go get for yerself..
When yer searching for tenths of a second, you can get desperate, and try crazy things...
and Single Fire...is also beneficial...not for saturation time...as if that was anything how could MSD function... [also a benefit BTW]
Single fire is Singularly Beneficial with Dual Plugs and high compression applications..especially with any even close to Hemi design..
As an aside... Back in the day we could make Unlimited HP and get a jillion miles to the Gallon, If we applied all of the Hyped up BS available in the JC Whitney catalog... Lots of "Stuff" out there is designed Specifically to appeal to the Consumer and their gullibility..
Proof is something that one needs to go get for yerself..
When yer searching for tenths of a second, you can get desperate, and try crazy things...
MSD's are not comparable because they operate differently..They are magnetos and produce a spark without having to allow time for coil saturation. Turning a magnet in a conductive field.
Fuel ignited does not explode but burns. Very fast but different from an explosion. Firing with 2 plugs helps to burn faster.The vortex engine design has been around over 60 years. The idea was to create fuel mix that was more like a tornado for faster burns. A hemi's problem was slow burns except for higher rpm's where vortex's aren't as big an issue. Vortexing is very effective in mid ranges. One way it's produced is the wedge shape of the combustion chamber. The squish area.
As for indexing plugs, the reason I would need the results of a dyno is many things could account for tenths of a second when a race bike is operated by the largest variable ( humans ). A dyno tells the truth. At 6000 rpm there are 50 precise timed ignitions per second. A fire fight. At higher rpm's a lot of fuel won't get burned. Not enough time. Straight pipes will loose power in mid ranges because they allow the cylinder to loose energy too fast.
Your last sentence is so true. Anyone that's been to Bonneville knows the crazy things racers try..
I'm getting carried away. Too much coffee.
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
no MSD does work but only to 3000 RPMs as the speed of the combustion cycle is met at 3000 - so the MSD then becomes a hi out put discharge ignition - our race car uses a 65 thousand volt coil and 11 MM plug wiring reverse wound outer wire and a center core wire wrapped in silicone conductive wire
your spouting from a text book - and who ever wrote it his hypothesis >>> not practical application - its 2 different things doing it for real and reading about it
your spouting from a text book - and who ever wrote it his hypothesis >>> not practical application - its 2 different things doing it for real and reading about it
Cruiser
Joined: May 2020
Posts: 117
Likes: 44
From: Corrales NM
no MSD does work but only to 3000 RPMs as the speed of the combustion cycle is met at 3000 - so the MSD then becomes a hi out put discharge ignition - our race car uses a 65 thousand volt coil and 11 MM plug wiring reverse wound outer wire and a center core wire wrapped in silicone conductive wire
your spouting from a text book - and who ever wrote it his hypothesis >>> not practical application - its 2 different things doing it for real and reading about it
your spouting from a text book - and who ever wrote it his hypothesis >>> not practical application - its 2 different things doing it for real and reading about it
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Seasoned HDF Member
Joined: Jul 2014
Posts: 8,610
Likes: 3,377
From: Cental, MI
no MSD does work but only to 3000 RPMs as the speed of the combustion cycle is met at 3000 - so the MSD then becomes a hi out put discharge ignition - our race car uses a 65 thousand volt coil and 11 MM plug wiring reverse wound outer wire and a center core wire wrapped in silicone conductive wire
your spouting from a text book - and who ever wrote it his hypothesis >>> not practical application - its 2 different things doing it for real and reading about it
your spouting from a text book - and who ever wrote it his hypothesis >>> not practical application - its 2 different things doing it for real and reading about it
I only use a car for groceries, and snow plowing!!!! But Our Dragbike has run very well indeed on Nology Hot Wires... Is that somewhat like the plug wire System you speak of????
DooWop; As far as the Human variable.... Who is operating the Dyno???
I can assure you ... no changes whatsoever were made to our Dragbike until we had established a Solid Baseline... this was Decidedly Not a thing taken Lightly.. The Dyno was Unreliable, [probably a traction issue]...while the Track ET was a Useable Tool...
Like John..... LOL Couldn't help it... Keep on Keepin on... Both of ya's...
Mundane is Boring!!!!
Last edited by Racepres; Oct 8, 2020 at 06:15 PM.
Seasoned HDF Member
Joined: Nov 2006
Posts: 12,878
Likes: 5,449
From: la la land jerzey
yea race same tech as what you using in plug wires
while i campaigned a race bike and rode it into the mid 90s before we went after road racing -
my kid i like the idea of 4 wheels and a 150 mph
while i campaigned a race bike and rode it into the mid 90s before we went after road racing -
my kid i like the idea of 4 wheels and a 150 mph