Bosch HKZ

[mrg3.6]

Knowing that the original Bosch HKZ unit in the early 911S was essentially introduced to eliminate 'plug fouling', can some kind soul please explain in simple terms to a (completely inept) layman the key 'evolutionary' differences between the 3-pin, 6-pin and 8-pin Bosch HKZ CDI units and what performance or other gains each configuration brought to our 6 cylinder oily bits?

Thx

Martin

[304065]

no difference in spark output
difference in how they are triggered
3 pin triggers with points
6, 8 trigger with magnetic reluctor wheel

[mrg3.6]

no difference in spark output difference in how they are triggered 3 pin triggers with points 6, 8 trigger with magnetic reluctor wheel

Got the points bit thanks and interesting to note there is no difference in spark output (which I didn't expect), so what distinguishes the 6 pin from the 8 pin (early turbo and RSR)?

Martin

[304065]

8 pin has separate ground and power wires for coil terminals, unlike six pin which has a single wire to the coil output and uses a common ground. That and the price.

[RSTarga]

so the RSR's didn't use points?

[304065]

so the RSR's didn't use points?

3,0 RSR had a Bosch breakerless distributor (reluctor-triggered, no points). However, you can trigger an 8-pin with points so I'm sure there are exceptions to the "rule."

[mrg3.6]

8 pin has separate ground and power wires for coil terminals, unlike six pin which has a single wire to the coil output and uses a common ground. That and the price.

Is there a good reason for separating the ground and power?

Does the 8-pin unit have 'built-in' circuitry to accomodate an adjustable 'rev limiter' or is this feature limited to the RSR variant?

Thx
Martin

[mrg3.6]

Again forgive my ignorance but what does the (third) 6-pin box bring to the 8-pin twin plug party:





(Photo's courtesy of elevenparts)

Martin

[MTemp]

It's a cdi from a 924 or 944 I believe.

[mrg3.6]

It's a cdi from a 924 or 944 I believe.

So what's it doing in a 75/76 RSR ?

Thx
Martin