Re: Dual plug reasoning?
[Re: superhog88]
#2827126
09/30/20 09:43 PM
09/30/20 09:43 PM
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Joined: Nov 2004
Posts: 25,050 Texas
GoodysGotaCuda
5.7L Hemi, 6spd
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5.7L Hemi, 6spd
Joined: Nov 2004
Posts: 25,050
Texas
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Is it absolutely necessary to run dual spark plugs Can you only fire one plug Will the engine run properly Is there a horsepower advantage to two vs one The stock coils fire both at the same time, unless you're planning on aftermarket wires/coils?
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Re: Dual plug reasoning?
[Re: GoodysGotaCuda]
#2827240
10/01/20 09:36 AM
10/01/20 09:36 AM
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Joined: Jan 2003
Posts: 8,022 Tulsa OK
Bad340fish
master
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master
Joined: Jan 2003
Posts: 8,022
Tulsa OK
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I know there has been people run them on one plug, and even made good power(turbo). I believe they ran them off of a Microsquirt ECU and used an LS coil to fire the one plug. You have to add some hardware to fire the stock coils with that setup. Not a big deal but when your trying to do it as cheap as possible one plug works.
68 Barracuda Formula S 340
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Re: Dual plug reasoning?
[Re: 340Cuda]
#2827281
10/01/20 10:34 AM
10/01/20 10:34 AM
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Joined: May 2012
Posts: 1,821 South Bend
John Brown
top fuel
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top fuel
Joined: May 2012
Posts: 1,821
South Bend
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I wanna know how you can fire two plugs at once off of one coil. Spark energy is supposed to follow the easiest path. How can two plugs both be the easiest path.
July 19th should be "Drive Like Rockford Day". R.I.P. Jimmie.
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Re: Dual plug reasoning?
[Re: superhog88]
#2827354
10/01/20 12:28 PM
10/01/20 12:28 PM
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Joined: Jan 2003
Posts: 25,785 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,785
Rio Linda, CA
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"Dual ignition promotes engine efficiency by initiating twin flame fronts, giving faster and more complete burning and thereby increasing power".
Aviation piston engines have dual plugs; during the engine run up prior to flight it's SOP to switch off one set of plugs, this produces a noticeable reduction in RPM called a "mag drop".
The INTERNET, the MISinformation superhighway
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Re: Dual plug reasoning?
[Re: John_Kunkel]
#2827428
10/01/20 03:10 PM
10/01/20 03:10 PM
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Joined: May 2012
Posts: 1,821 South Bend
John Brown
top fuel
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top fuel
Joined: May 2012
Posts: 1,821
South Bend
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"Dual ignition promotes engine efficiency by initiating twin flame fronts, giving faster and more complete burning and thereby increasing power".
Aviation piston engines have dual plugs; during the engine run up prior to flight it's SOP to switch off one set of plugs, this produces a noticeable reduction in RPM called a "mag drop". I can understand dual mags firing two plugs at a time. What I can't understand is one mag or one coil firing two plugs at the same time.
July 19th should be "Drive Like Rockford Day". R.I.P. Jimmie.
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Re: Dual plug reasoning?
[Re: Jerry]
#2827628
10/01/20 09:51 PM
10/01/20 09:51 PM
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Joined: May 2012
Posts: 1,821 South Bend
John Brown
top fuel
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top fuel
Joined: May 2012
Posts: 1,821
South Bend
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That makes more sense. TY.
July 19th should be "Drive Like Rockford Day". R.I.P. Jimmie.
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Re: Dual plug reasoning?
[Re: Twostick]
#2827903
10/02/20 02:11 PM
10/02/20 02:11 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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The early 5.7 has a coil on one plug and a plug wire from a coil on the opposite side for the second plug. My understanding is the second spark is mostly wasted, firing on the backside of the power stroke. It's purpose is mostly EPA related.
There is apparently a kit to to fire both plugs together.
Kevin Its called don't cross over the wires, just coil up the extra length and stick it in the hole next to the coil. Jacobs makes a short wire specifically for this, probably the "kit" you are thinking of butt it is very easy to do even with the stock wires.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Dual plug reasoning?
[Re: superhog88]
#2827962
10/02/20 04:29 PM
10/02/20 04:29 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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Very little advantage unless you are trying to light off something hard to light off, lean mixtures, very high compression... Very small HP advantage, very small MPG advantage, very small emmissions advantage, add up all those small advantages and they figured it was worth while.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Dual plug reasoning?
[Re: superhog88]
#2827964
10/02/20 04:29 PM
10/02/20 04:29 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
I Live Here
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I Live Here
Joined: Jan 2005
Posts: 12,419
Kalispell Mt.
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Very little advantage unless you are trying to light off something hard to light off, lean mixtures, very high compression... Very small HP advantage, very small MPG advantage, very small emmissions advantage, add up all those small advantages and they figured it was worth while.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: Dual plug reasoning?
[Re: superhog88]
#2828155
10/03/20 01:23 AM
10/03/20 01:23 AM
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Joined: Jan 2007
Posts: 10,132 A Red State
SNK-EYZ
I Live Here
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I Live Here
Joined: Jan 2007
Posts: 10,132
A Red State
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Back in 2003 I asked one of the plant engineers (Ram truck plant) why they used the dual plugs and he said it was strictly for emissions. When they had the crossover plug wires that one fired on the exhaust stroke is what he said.
They got rid of the plug wires after a few years and I believe they just used the computer to do the same thing.
Kayse can't keep up at all now. lol
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Re: Dual plug reasoning?
[Re: SNK-EYZ]
#2829756
10/07/20 11:51 AM
10/07/20 11:51 AM
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Joined: Dec 2015
Posts: 112 Michigan
ghinmi
member
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member
Joined: Dec 2015
Posts: 112
Michigan
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There's some good and some bad info on this post. Dual plugs are useful in that starting the flame travel from two points burns the mixture quicker. This requires less ignition lead (timing) and does have a power increase associated.
All gen3 hemis fire both plugs in a given cylinder at the same time!!! I'm not sure where people are getting info that one fires during the exhaust but that is not true. 2003-2005 with the crazy spark plug wires use waste spark to fire the plug on a cylinder 360 degrees away. For instance, when #1 is firing, one plug gets lit by the #1 coil and the other plug gets lit by the waste spark off of #6 coil. In 2006 they went to a '2 coils in one box' design and went away from the bundle of plug wires.
The above is why using a short plug wire to hook the coil to both plugs on a 2003-2005 coil is IDIOTIC. You might as well just run one plug at that point because the second plug is doing absolutely nothing for your combustion. The engine will have close to the same power potential as properly firing both plugs but require more timing to do it.
Long story short. If you have an engine management system capable of firing both plugs, do it. If not, don't worry about it but know that your timing numbers will be higher than anything else you see posted online to make the engine happy. And the short spark plug jumper wires are pointless.
1975 Jeep Cherokee compound turbo 5.7 Hemi/6 speed AutoX/Drag/Street. 9.97 @ 140 slicks, 10.74 in autox trim
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Re: Dual plug reasoning?
[Re: ghinmi]
#2834198
10/18/20 12:24 PM
10/18/20 12:24 PM
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Joined: Feb 2009
Posts: 773 Crofton, Ky.
rattler
super stock
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super stock
Joined: Feb 2009
Posts: 773
Crofton, Ky.
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I just added the short wires from Taylor to clean up the engine. This is on a 2005 5.7 in my 64 wagon. I was surprised that the engine revs higher at startup than it did before the short wires. It settles into the same idle after startup. Any ideas for the higher revs on startup now?
1957 Dodge truck, Snakeskin Green with a little stroker motor. 1964 Plymouth Savoy wagon ( my new project)
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