[HWYSTR455]

Well. I will add, in some cases you need a bigger, stronger spark, like boost, N2O, and leaner mixtures. (like newer cars).

In the mid-70s or so, in order to meet emissions, leaner mixtures were needed, hence where 'high energy' ignitions began.

You can hear people talk about 'blowing the spark out' in some discussions, and that's also where a 'need' comes from. It's harder to 'blow out' a larger more intense spark.

As a matter of fact, there are even some heads that have dual spark plugs, for that very reason.

So there is some science behind it.

Do YOU need it? That's for you to decide, and depends on your build. For an 'average' build, other than better tail pipe emissions, or ability to run leaner mixtures, probably not. But it does keep plugs cleaner, and is able to burn a wide variety of mixtures, as you might find in an 'less than optimum' tune on a hobby car.


.

[george kujanski]

I have a '91 Caddy Allante...the plug gap is specified at .060...OEM....widest OEM gap I've ever seen. I backed it down to .045 which is a more common HEI spec. Don't need to stress the ignition system.

George

[Sun Tuned]

Bill Jenkins did some testing back years ago where in some instances too much firepower will actually blow a portion of the mixture “cloud” away from the spark kernel and cause incomplete combustion.

So you are correct in that different applications call for different levels of intensity. Obviously top fuel comes to mind vs a 2 bbl 326.

A good example of everyone wanting more all the time is this. Around 1990-1998 Performance distributors used to sell 2 different HEI coils. A street and strip deal that was good to 7000, and a race coil that was good to 9,000.
They still do this although the coils have changed, they’re stronger now.

But back then everyone always wanted that race coil because it was “Better” somehow because it was a “Race” coil, and went farther in rpm range. Both would work on a street car just fine. However, the desk was, running the street/strip coil one could see a hot spark right off idle up to about 7200. The race coil tested under exact same conditions was visibly softer in spark intensity and put out noticeably less ozone smell up to 3000 Rome where from there on up to 9400 or so it was clearly superior than the street/strip coil, actually drew an extra amp while doing it.

So the moral of that deal was the guys trying to run that race coil deal on a car that never went over 6000 rpm were getting it done ,but they were also trading off a very important “punch” from off idle to 3000 for the bling factor of saying they had a race coil. And that off idle to 3000 range effectively was the most important area of the street range they needed anyhow.

As the rpm goes past 6000 , anything that that remotely looks like a properly timed spark will ignite the mixture. In other words it’s actually easier to ignite the mixture the higher the rom goes. The problem with actually getting this done in the real world is a non purpose built ignition will begin falling off at an even faster rate as tge rom goes up, and ends up falling short because it cannot keep up.

It’s amazingly easy to ignite a mixture charge at high rpm you just have to have the right equipment for that particular purpose, and the large majority of oem stuff ain’t gonna cut it in that arena.

[Formulajones]

Technically speaking on the boosted and nitrous stuff you tend to tighten the gap, not open it.

As you increase cylinder pressure and start making more power, the trend is to tighten the gap so the spark isn't blown out. Sometimes you'll see maybe .020 gap or so to compensate for that problem as even the high out put ignition systems dont keep the flame lit when gaps are too big

[Bill Hanlon]

Originally Posted by HWYSTR455

Well. I will add, in some cases you need a bigger, stronger spark, like boost, N2O, and leaner mixtures. (like newer cars).

In the mid-70s or so, in order to meet emissions, leaner mixtures were needed, hence where 'high energy' ignitions began.

You can hear people talk about 'blowing the spark out' in some discussions, and that's also where a 'need' comes from. It's harder to 'blow out' a larger more intense spark.

As a matter of fact, there are even some heads that have dual spark plugs, for that very reason.

So there is some science behind it.

Do YOU need it? That's for you to decide, and depends on your build. For an 'average' build, other than better tail pipe emissions, or ability to run leaner mixtures, probably not. But it does keep plugs cleaner, and is able to burn a wide variety of mixtures, as you might find in an 'less than optimum' tune on a hobby car.


.

Dual plug is old technology. Lots of aircraft engines. Even Ford flatheads.

[i82much]

msd ready to run with a programmable 6al2. no problems
other than a light wallet!!