What is Twin Spark and what does the 'J' Stand for?

[darrude]

Just a little query of mine, and I know i'm going to get flak for this, but what exactley is mean't by Twin Spark?

Does the spark plug fire twice per revolution, if so why, surley the initial explosion will take all the oxygen out of the cylinder.

Also why are the engines 'J', as in JTD or JTS.

Regards,

Darren

[euroboy]

There are 2 spark plugs per cylinder!!

I think JTS stands for 'Jet Thrust Stoichometric'.

The modern Twinsparks run the "wasted spark" to clean up emissions, they fire at the same time, in pairs.

JTS is as described above but I forget what JTD means

wrinx

[darrude]

The twin spark one has been bugging me for years!

Thanks

[Sunbar]

From a previous thread about twinspark engines......

http://www.alfaowner.com/Forum/gener...rk-theory.html (The twin spark theory)

Originally Posted by Hoygaard

Right.... Here we go again...

The twinspark setup does fire two plugs per cylinder per combustion cycle. Moreover, it's not the big ones that necessarily is the main plug per cylinder, actually coil 3 and 4 sit on top of the small plugs.

What's going on is referred to as lost spark ignition; this means that the engine management activates coil 1 and 4 at the same time and 2 and 3 at the same time. This results in both plugs fires in the combustion cycle on one cylinder and both plugs on the opposing cylinder fires late in the exhaust cycle. Whether this will ignite any unburnt fuel I don't know, but I really doubt so. But there is in fact an environmental benefit in this; a better ignition of the fuel, and in case one plug fails, the engine will still ignite the mixture, keep on running on all four cylinders and therefore not damage the catalytic converter and not harm the environment.

For further clarification, you guys might want to take a look at this drawing of the coilpacks and plugs

Clear enough
-- Hoygs

[Mitch166]

This according to Wikipedia:

JTD (uniJet Turbo Diesel) is Fiat Group's term for its current common rail turbodiesel engine range. The MultiJet name is used in the second generation common rail units. Most of the Fiat, Alfa Romeo and Lancia range has JTD engines. Ownership of the Fiat JTD design is shared with General Motors as part of a settlement of the failed merger between the two auto conglomerates. GM Powertrain Europe group in Turin, Italy manages their interest in these engines.

[Probusterrace]

Here's a link for the Wikipedia entry on the TS engine.

Linky.

[darrude]

Thanks everyone...

What a brilliant website that Wiki is, dwarfs do have kness after all.....

[Ant]

Darrude, this is AlfaOwner. It's hard to get flak here unless you actually look for it or behave badly.

So, ask around and have fun.