Dual Distributor
#1
Anti-Cupholder League
Thread Starter
Dual Distributor
Does anyone know why Porsche decided to use this odd dual rotor, dual cap distributor setup on the 964/993?
Perfectly good 12 wire distributors were available on several other marques.
I don't recall reading anything about this in Frere or other books...
Perfectly good 12 wire distributors were available on several other marques.
I don't recall reading anything about this in Frere or other books...
#5
Rennlist Member
A 12 cylinder cap allows one ignition coil to fire one of 12 plugs at a time. Not what our engines need.
Our engines require a means to have two coils each fire one of a group of 6 plugs at a time ... there are two separate ignition channels.
... Gregg
Our engines require a means to have two coils each fire one of a group of 6 plugs at a time ... there are two separate ignition channels.
... Gregg
#7
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#8
Rennlist Member
For a single 12 lead cap to work, it would require two coil connections and two rotors which would create two distinct ignition channels; one for each bank of plugs. I've never seen a single cap like that done, and I can't even think of a simple way to make that work. I suggest if there were a way to do it, Porsche would have updated the twin distributor before now.
.. Gregg
#9
You can see the rotor looks the same 12 leads out of the cap what happens inside the cap is a complete mystery. well at least to me it is😁
Last edited by JohnK964; 07-18-2017 at 10:43 PM.
#10
Anti-Cupholder League
Thread Starter
#11
#12
that setup still use's two ignition coils. I think they went the two cap route because with higher Resistance from the ignition system in our cars you would have more jumping and arching in side the cap. soon I will be distributor less.
#13
Rennlist Member
#14
I wonder how then the rotor works I suppose two concentric rings inside the cap could work with two pick ups on the rotor. Oh well this will give me something to ponder while I work at my mindless job👍
#15
Rennlist Member
Till then, one clue is that one of the HT coil leads appears to be central in the cap, while the second coil lead appears to be offset in the cap. From the little we can see of the rotor, it seems to be constructed in much the same way: a central contact, and an outer ring for the offset contact. That implies that the center contact fires 6 of the plug leads, while the offset one fires the other 6.
.. Gregg