[al lkosmal]

This is copied from an MSD troubleshooting site.

regards,

al


77turbocarrera
03-29-2005, 10:43 PM
My Porsche 930 3.0 turbo keeps eating rotors ever since I installed the 6 digital and HVC 2 coil. Car runs & drives perfect until the center portion of the rotor (epoxy) melts away. Any obvious solutions? Bad ground? Too much voltage?

I'm using Bosch ignition parts FWIW.

Thanks,
Vince
msdtechsupport2
03-30-2005, 08:33 AM
This can be attributed to a couple of problems. If there is too much resistance in the secondary system such as cap, wires or plugs then it would make it easier for the spark to arc through the rotor to the distributor as opposed to traveling down through the plugs. This can also be a ground issue; double check motor grounds. Make sure the battery is grounded to the motor and the chassis and that the motor is grounded to the chassis as well.

77turbocarrera
03-30-2005, 08:50 AM
I will try the grounds today. As far as secondary resistance, what range of readings should I look for in the cap, rotor and wires ( all new parts btw - bosch cap & rotor, magnecor wires.)

Can the spark plugs be tested also?

Thanks
Vince

msdtechsupport2
03-30-2005, 09:39 AM
Your best bet is to check for resistance and if you see something obviously high then this will likely be your problem. Unfortunately I don't have the resistance reading on the MagnaCore spark plug wires however you may contact them to find out what they should read. How much boost are you running? If you are running high boost and the plug gap is too wide it would make it difficult for the ignition system to jump that gap.

mpdevelopment
04-01-2005, 03:58 PM
The Bosch rotor you are using has A 5k ohm current limiting resistor encapsulated in the black glyptal paint between the center and the distributor wiper end. With the 450 milliamp current provided by the Blaster HVC II coil the resultant peak power dissipated in the resistor is over 1000watts this will heat up and destroy the resistor. I have tested the 6plus with blaster hvc II on the bench and it will heat up a 1k ohm coil wire quite alot. You will have to solder in a fine jumper wire in place of the resistor.

mpdevelopment
04-01-2005, 04:21 PM
Just did a test with a 6AL + HVC II coil running through a Bosch 930 turbo rotor In less than 60 seconds the rotor was smoking and I could not pick it up (VERY HOT) This was at a simulated 4500 rpm. I have not tested a Bosch CDI system yet but I know the energy stored in the capacitor is approx 80 millijoules. I also believe the bosch system is designed for a fast rise time not for high current. I am currently experimenting with a twin plug Porsche 911 ignition using a Digital 7 Plus with two Blaster HVC coils in parallel this system will use less power than two 6AL boxs and will provide similar spark energy.