plug gap with Dyna and Accel coils/wires?

Am thinking that dual spark plugs in aircraft engines is largely for redundancy as a back-up spark in case one plug malfunctions, and not so much toward power enhancement.

Aside from redundancy needs, a single centrally located spark plug in a four-valve cylinder would seem to serve as well as dual side-located spark plugs in a two-valve cylinder.

In the same size and shape cylinder, the flame front ignited by a centrally located spark plug travels distance from center to circumference (half-way across the diameter), which seems approximately equal to distance traveled by each of the two simultaneous separate flame fronts ignited by two side-located spark plugs where flame front from each circumference travels to where they meet in the center.

In other words, each flame front from side-located dual plugs travels 1/2 the diameter, same distance as the single flame front travels from a single centrally located spark plug.

Another espoused theory is that with high domed pistons, the flame front from a single side-located spark plug is slowed when squeezing across the dome to the other side where there's no spark plug. Which would seem to be most tenable in a two-valve cylinder with a single side-located spark plug.

From high in the peanut gallery, nose bleed section. :lol:

Good Fortune!

Patton wrote:
Another espoused theory is that with high domed pistons, the flame front from a single side-located spark plug is slowed when squeezing across the dome to the other side where there's no spark plug. Which would seem to be most tenable in a two-valve cylinder with a single side-located spark plug.

Good Fortune!

i like this theory. i wonder if its just the hemi shaped chambers that get 2 plugs /
have u seen 2 plugs in a flat top ?

You have to run higher voltage ignition on race engines because with higher compression, the spark has to travel through more air which means it has to overcome more insulation. This means the coil has to be able to withstand higher voltage and the ignition module has to withstand higher voltage, and plug wires, etc.

But I think the point Otto was making, about dual plugs, is that you can make an engine run fine with a faster, controlled, burn, without pre-ignition and detonation. Since a larger plug gap basically accomplishes the same thing, that's what he's doing.

As far as why doesn't the manufacturer do that... well it does stress out ignition components and may shorten their life, but electronic has gotten much better in 30 years. Also, there may be an emissions issue that we are not aware of. Also, maybe there is a temperature issue in different climates.

These guys seem to have it figured out..... :lol:

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Regarding spark plug gap, we only make two sizes. Our standard size, which has an equivalent gap of about .120" and the "S" plug, which has an equivalent gap of about .090". The standard plug requires between 21,000 to 25,000 volts to fire under full pressure. Our "S" plugs require between 16,000 to 18,000 volts to fire under full pressure. The "S" plugs are designed for high compression racing applications, turbocharged, supercharged, NOS, etc. The gap on a Torque Master spark plug cannot be changed as it is an integral part of the overall design.

Purpose of the Spark Plugs

Every automobile engine runs because of a mixture of fuel and air being fed into the combustion chamber. A spark is provided at just the right moment of piston position. This spark ignites the fuel and air mixture which results in an explosion where hot gases expand and the resulting pressure is applied to the top of the piston, forcing it down.

Delayed Burn

"Delayed Burn" is nothing more than that delay time that occurs between the spark flash of the spark plug and the first visible flame of combustion. The fuel-air mixture inside the combustion chamber may vary from one power cycle to the next. The time required to ignite the combustible mixture in order to start a strong, self-sustaining flame front varies directly with the consistency of many factors. Delayed burn is the delay time caused by a weak propagation of flame front which results in slower combustion and a loss of efficiency.

On-Time

Delayed burn takes its toll on engine power. When "On-Time" combustion occurs, a very fast, proper delay time, strong flame front is initiated within the combustion chamber. Gas pressure rises fast, expands and peaks just as the piston starts to approach top dead center (TDC). The result is maximum engine power being delivered to the top of the piston at just the perfect point or position.

Many factors contribute to the foregoing, such as: compression ration, combustion chamber shape, spark plug location, spark plug type, ignition system and ignition coil, intake fuel and air temperature, and the temperature of the engine itself.

The last, engine temperature, is of extreme importance.

Why Delayed burn is BAD?

If the ignition point of combustion is weak, as with "Delayed Burn", the crankshaft can actually rotate to to 20 degrees past TC. Having done so, the piston can't take full advantage of all the available expanding gases created by combustion. The result is a big loss of power and torque.

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We don't believe that "Delayed Burn" can be completely cured because nothing is perfect. We do believe that with the installation of a new set of Torque Master spark plugs, "Delayed Burn" can be held to a minimum. Torque Master spark plugs make horsepower and torque on their own, no other spark plug can match this kind of combustion efficiency. The Torque Master spark plug will deliver 100% to 200% more spark exposure to the combustion mixture.

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Torque Master spark plugs will outlast all other spark plugs, even the best platinum design. The reason is because of our patented stainless steel tip design which requires no gap setting whatsoever and the ceramic insulator itself is used as a spark path -- this is called 'surface conductance'. This surface conductance prevents formation of any fouling substance to accumulate on the ceramic insulator. This patented feature permits the spark plug to operate at top efficiency throughout its life -- which have proven to be as much as 11 years and 243,000 miles without service or maintenance of any kind (Sandy Howard and his Ford station wagon)..

www.newscionparts.com/product/?id=1779

Not to be outdone..... the new AC "Rapid Fire" snazzy jazzy spark plug (look at the tip of the center electrode):

Heh, yeah. I think some really old spark plugs actually looked like that. My friend had some old Kaw two-stroke that had plugs like that in it. It had the "effect" of not being able to cross a "field" without fouling.

:laugh: