Dual plugs on early 'performance' motors

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fordconvert
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Dual plugs on early 'performance' motors

Post #1 by fordconvert » Wed Feb 20, 2008 10:56 am

Why did most of the very early upper end motors have dual spark plugs?
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Post #2 by ludwig » Wed Feb 20, 2008 11:27 am

Fatter spark, better fuel ignition and more complete burning.

I always wondered how they could coordinate the sparks to flash at exactly the same time in order to achieve the desired effect.
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Post #3 by BIGREDRASA » Wed Feb 20, 2008 11:59 am

ludwig wrote:Fatter spark, better fuel ignition and more complete burning.

I always wondered how they could coordinate the sparks to flash at exactly the same time in order to achieve the desired effect.


I had thought the sparks were sequential, for a "longer" spark.
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Post #4 by ludwig » Wed Feb 20, 2008 12:02 pm

And the difference is? [Vis-a-vis combustion/ignition?]
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Post #5 by BIGREDRASA » Wed Feb 20, 2008 12:09 pm

ludwig wrote:And the difference is? [Vis-a-vis combustion/ignition?]



There some of the earlier electronic ignition systems that woud fire the plug twice, to improve the burning. Don't recall the brand. It's getting so it feels like my head is like an overflowing file cabinet, and stuff flies out of the open drawers. :(
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Post #6 by ludwig » Wed Feb 20, 2008 1:03 pm

Dual-Strike!! Also: Second-Strike! Yesss!

The Mazda Rotary had two plugs to ignite all the fuel in time on account of the wide quench area.
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Post #7 by myplague5 » Wed Feb 20, 2008 3:09 pm

My 4 banger nissan uses 8 plugs....
Try kicking it, that always works on my spaceship...

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Re: Dual plugs on early 'performance' motors

Post #8 by Lazy JW » Wed Feb 20, 2008 8:51 pm

fordconvert wrote:Why did most of the very early upper end motors have dual spark plugs?


Because the early ignitions were pretty feeble and not too reliable. Most piston engines for aircraft use two plugs.

Some early fire trucks used twin spark plugs, one fired by a battery/coil ignition and one fired with a magneto.
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Post #9 by fordconvert » Thu Feb 21, 2008 9:42 am

By early I was thinking like pre 1930's. I know about aircraft and even my 05 dodge had dual plugs. I would assume now days it is a sort of staged concept. I just wonder if the early ones were hi tech or if they were just doubling their chances of getting a spark.
TJ H

Had a 66 mustang coupe, traded in for a 93 convert 2.3.
73 Eldorado convert 8.2 megasquirt, 80 Eldorado 5.7 diesel, 96 Suburban 6.5TD, 05 Magnum 5.7 hemi.

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Post #10 by myplague5 » Thu Feb 21, 2008 4:18 pm

Well considering that my Nissan had the main plug to the exhaust side screwwed up and ran like crap til it was fixed, I think they were just increasing their chances of getting a spark. It ran like crap when anywhere near WOT, get a new wire and it runs just fine now.
Try kicking it, that always works on my spaceship...



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Post #11 by ludwig » Thu Feb 21, 2008 6:42 pm

fordconvert wrote: early I was thinking like pre 1930's. I know about aircraft ... I just wonder if the early ones were hi tech or if they were just doubling their chances of getting a spark.


Think 6 volt system. How bright were the lights? Spark's gotta be similar.
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Post #12 by fordconvert » Thu Feb 21, 2008 8:10 pm

How many of the early setups were mags vs. coils? The model T's I worked on had both, and individual coil packs mounted right up next to the plugs.
TJ H

Had a 66 mustang coupe, traded in for a 93 convert 2.3.
73 Eldorado convert 8.2 megasquirt, 80 Eldorado 5.7 diesel, 96 Suburban 6.5TD, 05 Magnum 5.7 hemi.

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Post #13 by big blue » Wed Feb 04, 2009 11:07 pm

The late model dual plug systems are great for emissions on cars and trucks, aircraft IIRC have to have a redundant ignition system (falling out of the sky doesn't feel good) and the early ICE's used them to crutch weak spark systems for improved performance. The European high enders like Maserati used twin plugs on their inline 6, which was nothing but a barely detuned GP design. But really, if the engine has a good chamber and piston design you don't need it.

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Post #14 by Thad » Thu Feb 05, 2009 9:51 am

Kid's '98 Mazda 4 cyl pick-up had dual plugs.

And IIRC --- Multple Spark Discharge = MSD

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Post #15 by shmoozo » Thu Feb 05, 2009 4:34 pm

ludwig wrote: ... Now, let me see. What is the second chord of the blues progression again? ...


An even better question, or riddle, of you will, is this -- What is the sound of a one hand Clapton?

Answer: An unfingered, open-tuning chord. (The exact sound will depend on the guitar's specific tuning.)

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Post #16 by Lazy JW » Sat Feb 07, 2009 10:33 am

Here is a link to a LONG thread over at www.speedtalk.com about dual plugs. Some very interesting stuff. You have to be a member and logged in to view. Very worthwhile.

http://speedtalk.com/forum/viewtopic.php?t=14577
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