dual plugging

Once again considering dual plugging my '88
BMW airhead. Supposedly, this strengthens
the low end and allows better running on regular
or 89 octane fuel. Also supposed to allow a
bump in compression.

Job would require a new coil setup and a
small diameter plug hole tapped into each
cylinder.

Any thoughts on this mod ? Good idea ?
Not so good ? Downside ?

 

All reports I've read say it's a mod well worth doing, especially when
you consider the antique combustion chambers and gas flow that the
standard single plug has to cope with.

 

Combustion chamber shape isn't actually that bad, the trouble is that
BMW increased the capacity by increasing the bore, so the flame front
has to travel considerably further on bigger engines, with all the
assorted ill effects of that.

It's a worthwhile modification, but I'd be tempted to go the whole hog
and also use an ignition system that was designed for dual plugged
heads. A German company called Q-Tech does make complete systems for
this using R1100 coils - I've used their parts before and they "just
work". Only problem is that I don't know if the guy speaks any
English...

 

Try:

"Vas ist der price of der duppel schparken-lichten zystem, mein herr?"

 

The cheap dodge is go to the breakers yard and get the twin lead coils off a
Jap-4.

 

The trick seems to be matching resistance on the
dual plug coil to resistance the single plug one.