Perfect spark plug?

[454Casull]

Assuming an infinitely powerful ignition distribution system, what gap would you use? What electrode positioning would you use (extended, surface-fire, Halo-type, standard)? What electrode material would you use? What electrode plating would you use, if any? What insulation would you use? What shell material would you use?

Also, do you believe in that HotWires stuff?
Link

I would probably use a surface-fire plug /w a gap of 0.1-0.5", an electrode material of ELKONITE 2050C, iridium plating (because I don't know the inertness of the material), and probably a Ceralloy 418 insulator.

ELKONITE 2050C - 0.0297 ohm-mm²/m electrical resistivity, 330W/m-K thermal conductivity, up to 3400C melting point.
Ceralloy 418 - low thermal expansion, high dielectric constant, 250W/m-K thermal conductivity

[YellowMaranello]

Originally posted by 454Casull

I would probably use a surface-fire plug /w a gap of 0.1-0.5", an electrode material of ELKONITE 2050C, iridium plating (because I don't know the inertness of the material), and probably a Ceralloy 418 insulator.

ELKONITE 2050C - 0.0297 ohm-mm²/m electrical resistivity, 330W/m-K thermal conductivity, up to 3400C melting point.
Ceralloy 418 - low thermal expansion, high dielectric constant, 250W/m-K thermal conductivity

I think I'd use a blue one.

[454Casull]

I didn't ask colour...

[YellowMaranello]

Originally posted by 454Casull
I didn't ask colour...

Seemed like the thing to say at the time. You wouldn't happen to know of any links where I could go and read up on spark plugs would you? I know what most of it is (self explanitory) but do you know where I could read about the benefits/downfalls of certain aspects of a sparkplug? Unless you feel like explaining it of course. I just hate reading stuff and not knowing what it is or what it does.

[higgimonster]

Assuming an infinitely powerful ignition distribution system

if you mean infinite power then i would scrap theplugs for an electric motor

[454Casull]

Well if we had infinite power we wouldn't really need to worry about motors at all...

[454Casull]

Halo spark plugs
Data on Halo plugs
Brief overview of spark plugs
Our very own

[Evil Result]

Hey i'm new here.. great forums

Anyways i think the best type of spark plug would have no protruding electrode, where the gap would be based upon the ceramic insulator and the outer electrode would be level with the center electrode so the spark would have to jump over the ceramic gap this would expose as much spark as possible.

The halo puts a ring and several supporting electrodes infront of the spark blocking the ignition, not to mention all those components don't have much area to conduct heat away from the electrode.. might cause pre-ignition.

[Moppie]

How about no spark plug at all, but instead a series of electrodes in the head and compustion chamber and piston face, so that the spark could be spread and moved around inside the combustion chamber to control the rate of combustion and its start point depending on RPM and load?
i.e. instead of a Twin Spark type set up, you could get a 10 spark or more set up. Although clearly the current required to jump a spark from the top of the combustion chamber to the top of the piston face, or edge would require rather a lot of current.

[MustangRoadRacer]

Champion makes the best plugs.

[Evil Result]

Originally Posted by Moppie

How about no spark plug at all, but instead a series of electrodes in the head and compustion chamber and piston face, so that the spark could be spread and moved around inside the combustion chamber to control the rate of combustion and its start point depending on RPM and load?
i.e. instead of a Twin Spark type set up, you could get a 10 spark or more set up. Although clearly the current required to jump a spark from the top of the combustion chamber to the top of the piston face, or edge would require rather a lot of current.

I see a whole world of spark insulation issues, so the spark would go from the cylinder head to the pision and not take another route.

i was thinking something along the lines of F1 racing engine spark plug design... yet simpler and less expensive.

[454Casull]

Wow... Who resurrected this one?

I'm embarassed to see myself as a noob.

I'd pick a Halo-type design /w titanium diboride electrodes and a serrated inner edge, now.

[Evil Result]

http://www.picknowl.com.au/homepages...tech/spark.htm
"(F)Split-Fire/Ring of Fire: Again the possible advantage is better spark exposure by splitting the ground wires around the center wire. However, this ground wire has more mass and actually shrouds the edges of the center wire badly and secondly its additional edges which should give longer wear life, create extra hot spots in a racing application. As for the more spark energy claim, as long as you compare "apples to apples", there is no difference compared to any standard gap plug. Any difference would be to compare resistor to non-resistor or auxiliary gap to standard plug. As for the multiple spark claim, it can be explained by the arc of lightning. It's the best example of "one charge/one arc". If the plug receives one charge, it will deliver one arc. As the coil collapsed, some small oscillations create refires, but these are insignificant to performance."


http://www.edelbrock.com/automotive/sparkplugs.html
Regular Gap

"This gap style positions the spark approximately 1/16" into the combustion chamber. Many of the coldest heat ranges have a modified (shortened) ground electrode. This helps expose the spark to the mixture and protects against pre-ignition from an overheated ground electrode."

Surface Gap "V" Gap

" A surface gap plug provides exactly what its name describes... a gap at the surface of the combustion chamber. The gap is a .050" annular configuration. The center electrode and insulator tip operate extremely cold (no heat range rating) and are, therefore, nearly impervious to pre-ignition. However, fouling deposits are always present and cannot burn away. These types have limited use in racing. A special ignition system with very high energy and a very fast rise time (CD) is required to fire the gap when fouling deposits are present. The insulator tip does not operate hot enough to allow reading of the spark plug during engine tuning. The exceptions are the G52V and G54V which have surface air gaps with sufficient insulator nose length to give some heat range. These are used in Formula 1 engines. C53VC, C55VC, and C57VC are of similar design and use a 14mm thread diameter. These are designed for small-block Ford and Chevy engines used in Winston Cup type racing. There are also "S" type plugs available in this design with identical heat ranges."

Personally i wouldn't use the halo spark plug even i my smog dog, the 3 supporting grounds and ring are prone to making more hotspots or even breaking off.... i would use a regular plug and cut back the ground so there would only be 1 quenching location and not 3 or 4 if you count the ring.

I'm shure the "V" gap could be modified to run hotter to avoide fouling... the ground would also have more surface area for the spark to avoide "point erosion".

By now i'm shure you think i'm a stuck up kid, some noob who thinks he's right, think what you might. Just trying to save time, money, and effort.

[SaabJohan]

A regular gap is the best design (called J). Projected noses are used to move the spark closer to the center of the combustion chamber which is the best placement. A good electrode is small and made of a material which is "inert" and has low resistance (like iridium).

Surface gap plugs are used in F1 mainly for the reason that a J gap type of plug will fail because of vibrations, and that the combustion chamber needs to be small to keep the CR up. Racing plugs are very cold since they run with full throttle for the most time. The diamter of a F1 plug is also very small, around 6-8 mm against about 14 mm for a conventional plug.

Where electronic control systems are involved a resistor plug should be used.

Saab had a system which used the a plug and an electrode on the piston. Now they have a system where the injector and plug is combined and it has variable gap distance. I belive the system is of capacitor discharge type and it's designed to be used in an direct injected engine which uses exhaust to "fill up" the cylinder under part throttle conditions (requires a powerful ignition system).

Tungsten or molybdenum based alloys (like Elkonite) shouldn't be used as spark-plugs electrodes since they aren't inert and they requires special ceramic coatings when used in and environments with oxygen.

[SaabJohan]

In http://www.automotivearticles.com/ge...e&articleid=18 the following statement is wrong:

"2) To fine tune the temperature of the combustion chamber. Number 2 is the "heat range" of the plug"

The heat range of a plug is simply the plugs ability to conduct heat from it to the cylinderhead. This is so that the plug can keep a running temperature of between 400 degC and 950 degC. At higher temps the plug can get damaged and/or pre ignition can occur, at lower temps the plug won't "self clean".