1978 Porsche 928 body
1989 5.0L 32V V8 engine
78 2.75 drive ratio rear mounted transmission
V-1 Vortech Supercharger
Engine Build:
Swaintech www.swaintech.com coated pistons, ARP Rod bolts,
ARP head studs switched from OEM head bolts
Cometic Headgasket
Forged early 928 rods
944S2 valve springs
928 S3 (928 from 85-86) Cams (Shortened and bearing surface moved by Elgin Cams)
Planned: Side plates on dual resonance intake for more volume
VEMS Process:
IGNITION: Porsche Cayenne Coils fit PERFECTLY into the 928 32V heads, almost as if they were meant to there.
PNA- 721 043 00 430 “Car Tool 9” 26.01 and this is a pack with two male plugs for the coils. They are without wires, and you would need 4
948 602 104 03 “Pencil Coil” 12.21(!) dollars
PNA 721 043 00 504 “Harness Re” 67.44. Its enough terminated wires for two plugs, so you need 4. They are crimped onto the metal female receivers that slide into the plug itself, and have rubber gromits and about 12 inches of wire.
Partial Description of Wiring diagrams for Coils:
I took some time to analyze the drawing. It's almost illegible, but I did figure out some useful info. The coil plug has 4 wires and they are labeled A1, A2, A3, A4. On the drawing, the wires come out of the plug, left to right, A1, A4, A3, A2. A1 is ground. A4 is the pulse input. A3 is +12 volts. the function of A2 is sort of a mystery. It's a small wire only 1mm in diameter. The color as near as I can tell is brown/black. It goes to something called MM1 as near as I can read the drawing. Four coils go to MM1 and 4 coils go to MM2. Since this wire appears to be connected through a diode internally in the coil to the low side of the secondary winding, it may be a sense line to feed back some spark signal characteristic to a "black box" ignition control unit. I know some ignition units sense the ionization characteristics of the spark to determine if detonation is occuring. I don't know enough about the Cayenne to know if this is the way the detonation detector works or not. The drawing if the coil internals is quite basic with not enough detail to know what's really going on in there. It is possible the coil would work with only 3 of the 4 wires used. That is ground, + 12 volts and a trigger pulse. The dwell either being controlled by the trigger pulse length or through feedback from the A2 line. If the latter, then the A2 line is probably necessary and should only be used with the Cayenne control unit. Some experimentation may be necessary.
I am trying to get the PDFs of the wiring diagrams up on photobucket so I can post here.