Dual Spark Plugs

[Germanengineering]

I don't know if F1 ever tried this. Would you gain more power with dual spark plugs and would you need to ad more valves?

[Carlos]

If memory serves ...The 3 litre Maserati V12 (1966) derived from the block of the 1956 Maserati 250F V12 used a 2 plug cylinder head, first in a 3 valve configuration, in 1967 the engine was converted to 4 valves, not sure if it retained 2 spark plugs, power was probably 375 HP. Cooper used it both seasons. I think that was the only 2 plug head of the modern era ... if you call '66 modern - as I do

[Germanengineering]

I just read that the new Dodge Hemi uses a dual spark ignition to reduce emissions.

[flynfrog]

ford rangers (truck) used them in the early 90s for emissions

[WhiteBlue]

http://argent.fia.com/web/fia-public.ns ... 2-2010.pdf

U5.9U Electrical systems :
U5.9.1U Ignition is only permitted by means of a single ignition coil and single spark plug per cylinder. The use of plasma, laser or other high frequency ignition techniques is forbidden.
U5.9.2U Only conventional spark plugs that function by high tension electrical discharge across an exposed gap are permitted.
Spark plugs are not subject to the materials restrictions described in Articles U5.14 and 5.15U.

Double spark plugs are illegal!

[autogyro]

I just read that the new Dodge Hemi uses a dual spark ignition to reduce emissions.

The hemi chamber shape is not the best for burning petrol cleanly.
It works far better in the large capacities with a 'clean' fuel with better burn control like ethanol or methanol.
Two plugs for such a poor shaped chamber is a compromise.

[Tim.Wright]

I think Vettel would approve of an extra spark plug in each cylinder



Tim

[marcush.]

a spark plug in a combustion chamber is really a nasty noise I would rather avoid to hear.

[DaveKillens]

In aviation, dual spark plugs per cylinder is common practice. In fact, aircraft reciprocating engines carry two completely independent ignition sources, obviously for reduncancy and safety.

A second use for two spark plugs is to compensate for poor fuel burn, or an irregular flame front.

Additionally, the physical geometry of the combustion chamber, the location of the valves, and requirements for coolant passages may dictate spark plug placement.

[autogyro]

In aviation, dual spark plugs per cylinder is common practice. In fact, aircraft reciprocating engines carry two completely independent ignition sources, obviously for reduncancy and safety.

A second use for two spark plugs is to compensate for poor fuel burn, or an irregular flame front.

Additionally, the physical geometry of the combustion chamber, the location of the valves, and requirements for coolant passages may dictate spark plug placement.

In the 'Bulldog' engine fitted to the Auster AOP9 as used by the British Army, they made a complete joke of the safety issue, much like in twin engined but single gearbox/rotor helicopters.
On the Bulldog they fitted dual magnetoes and dual plugs but drove the magnetoes off one drive gear, so much for redundency for safety.
This is why I will not fly in helicopters under 500 feet. Some may have two engines but they only have one gearbox and in most cases one rotor. Under 500ft and you are in a potential brick with no height to go on autorotate. The twin rotor tilt wing joke the Osprey is even worse with so much machinery to go wrong and absolutely no glide capability, it is and is proven as a death trap.

[Belatti]

The first thing that comes to my mind when you talk about twin spark is Alfa Romeo.

Wiki pretty resumes it all:
http://en.wikipedia.org/wiki/Alfa_Romeo_Twin_Spark_engine
And the main reason of its benefits:

The two sparks on the 8V Alfa Twin Spark engines fire at the same time per cylinder and this makes the fuel mixture burn faster than single plug ignition because it is fired from 2 different places simultaneously. So less ignition advance could be used and also leaner mixtures could be burned. The 8V engine also has 8 identical spark plugs. They are symmetrically located at opposite sides of the combustion chamber. There is no room for a center positioned spark plug because the 2L version of the 8V engine use a 44mm intake valve and the two spark plug holes are on the sides of the 2 valves.

The idea looks fine but I have my doubts. Two "flame fronts" (or however that is called in English) colliding doesnt look good. I would like to know also what about the mixture swirl at the entrance of the combustion chamber at different speeds.

More recently I think Bajaj India have developed a system for low CC bikes.

[Ted68]

In Porsche air-cooled flat sixes, the dual-plug arrangement is used as an engineering band-aid.

A second plug is added on the opposite side of the combustion chamber to more effectively burn the mixture and allow higher compression ratios. What happens is that the dual flame fronts fire at opposite sides of the mixture and travels toward the center of the chamber. In effect each plug fires half the mixture.

In a 4-valve head the second plug is not needed because the flame front travels from the center of the chamber and still only needs to reach half the diameter of the bore to ignite the entire mixture.

The Hemi is also a 2-valve engine like the old Porsche which precludes a center spark plug.

[autogyro]

They all work so much better with proper fuels like ethanol methanol and LPG but what the hell the oil industry has to be fed.

[DaveKillens]

As Ted68 pointed out, a four-valve head with the spark plug in the middle contributes to an even and complete fuel burn. And this works pretty good on Formula One engines. Now, if anyone thought a second plug should be installed, that would add extra weight and complexity. Since one plug seems to be capable of doing the job, you have to balance reliability against extra mass.

What happened to Vettel's engine is a very rare occurance, plug failures don't happen very often.

Of course, if you believe that story. Maybe I'm too cynical, but I have seen in many instances where a team blames a generic part instead of laying blame and humiliation on a partner supplier. That being said, everything I have seen about the sudden loss of power does confirm it could have been a plug.

[Ted68]