Combustion chamber & twin plugs

[Craig Pugsley]

> 	Also heard of American Eagle making that 12 cylinder engine for drag
> racing with 3 plugs per cylinder on a 4 valve engine.  The chambers were
> so huge that a central plug wasn't enough.

FWIW, all mazda rotarys use a twin plug arrangement, as the combustion
chamber is very long and thin (compared to a piston engine).
Realistically, disconnecting the "secondary" set of plugs makes little
noticable difference to the power output (on mine at least).
I think it's mainly for emissions.

Also, the 4 rotor engine used in the le mans car has a 3rd plug-probably
to get the last 1-2% power at 10,000 rpm ;-)

Cheers,
Craig.