Quote:
Originally Posted by Mr.P 911T 1970
Thanks, Dave. Appreciate the values and will certainly use these over the next couple of weeks. The biggest take away from the articles you and Thomas provide and lends creditability to Bob, is that the MSD 8222 is acceptable replacement when it comes to reliability and as a "suitable" replacement for Bosch-Black; performance isn't really gained above what Porsche originally intend. I'm getting a longer spark, weaker current.
I'm running NGK5 series spark plugs- would a larger gap support this longer, weaker current. It seems ok now.
Do you or anyone know of a secret hiding spot for the Bosch transformers - the black ones, made in Spain or Germany?
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Yes, using coils with higher primary inductance will provide a longer spark pulse width, which allows for a more complete combustion.
As an example, the original small black Bosch coil with a primary inductance of .20mH will develop a spark of about 30us.
When the blue Bosch coil with a primary inductance of about 12mH is used, the spark pulse width is about 140us, over 4X the spark pulse width.
Obviously, it's nowhere near the better spark of an inductive discharge system which approaches about a one millisecond spark pulse,
which explains why all Porsche vehicles now use an inductive discharge ignition system.