Had the same question a while back - here is the response from Dr. Booost:

Hi !
So, let's make this clear as mud....

All DI cassettes are "capacitive discharge".
Short description of RED cassette:
The DI Cassette is feed with B+(12V), the B+ is then converted to 400 VDC, inside the DI C. There are four individual ignition coils.
Between the 400 V capacitor and each coil there is one thyristor per coil.
When the ECM triggers the thyristor, energy that has been stored in the capacitor will be dumped into the primary (winding) side of the ignition coil.
As a result there will be a hi voltage across the secondary side.
The duration of the "spark" is quite short, because the use of a thyristor. (DC spark)


BLACK cassette, well more or less the same description, BUT with one important difference: we don't use a thyristor to dump the energy, we use a triac.

The difference between a thyristor and a triac is that the thyristor will only conduct current in one direction, triac in both directions.
And that's why we get a AC spark in the BLACK cassette.
The BLACK cassette's spark duration is approx. three times longer than the RED.

On the New 9-3 SportSedan we do not use capacitive discharge ignition system anymore, we've got an inductive system.
Still one coil per cylinder, and still the ionization concept to analyze the combustion conditions.


posted by 135.214.4...

• DI Cassette replaced with a RED version? Is this right?, sph3re, Sat, 22 Nov 2003 12:22:47
  • Old Dr Boost Post, sjackson, Mon, 24 Nov 2003 05:24:22 <-- Viewing This Message
  • black ones on EBAY recently for $229, TimBrown, Sat, 22 Nov 2003 19:31:58
  • your indy is making money on the red/black swap, sb, Sat, 22 Nov 2003 15:54:47
  • Re: DI Cassette replaced with a RED version? Is this right?, frank , Sat, 22 Nov 2003 15:43:31
  • Update - Indie mech says red & black are identical. (+), sph3re, Sat, 22 Nov 2003 13:15:25
    • Don't know what to say. Tried a red one once on a 9-5, SWEDECAR , Sat, 22 Nov 2003 15:25:30
    • According to the EPC..., keeton, Sat, 22 Nov 2003 14:20:16
      • They used part number # 9178955 - n/m, sph3re, Sat, 22 Nov 2003 14:34:12
        • Re: They used part number # 9178955, keeton, Sun, 23 Nov 2003 11:07:52
  • Re: DI Cassette replaced with a RED version? Is this right?, Ian Glenday , Sat, 22 Nov 2003 12:57:14
  • Re: DI Cassette replaced with a RED version? Is this right?, murphwiz, Sat, 22 Nov 2003 12:54:09
    • Re: DI Cassette replaced with a RED version? Is this right?, JA, Sat, 22 Nov 2003 15:35:42

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