Distributorless Ignition
08-04-2001, 01:34 PM
#1
Nordschleife Master
Thread Starter
Distributorless Ignition
I have to replace at least my cap, rotor and wires, probably coil wouldn't be a bad idea, on my 951. I'm afraid to take off the plug wires to change plugs cause I'm sure they will crack into a million pieces. 
So, I'm looking into distributorless ignition options. I don't want to spring for stand alone engine management because of the obvious tuning and installation headaches and from what I can see, most everyone agrees they are not worth it unless you are adding all sorts of new equipment like larger turbos, MAPs, etc, and getting output up in the 350 RWH area and you can't make the engine work without one.
There are ignition kits like Electromotive's HPV-1 for $475. To me the drawbacks of that are they seem to totally ignore the Motronic ignition maps and senors and replace it with a fairly simplistic straight line map with a couple of different RPM ranges. (At least I think Porsche made a more sophisticated ignition map in the Motronic.) And it doesn't seem to incorporate knock control and boost issues.
To get to an ignition system that would seem to be sophisticated enough, it looks like you are *well* past half way to full standalone engine management in cost and installation effort.
Can't the Motronic unit tell and send out a signal which cylinder to fire without the distributor?
Does anyone, or how hard would it be to DIY, make a multi coil pack that would take the original Motronic signal to the coil and then figure out which cylinder is up? Calculate this either by the existing reference sensors on the clutch housing (or are these really not reference sensors?) or add a new crank trigger wheel?
I would think this would be a fairly straight forward deal if all you were doing is relying on the Motronic signal and then electronically replacing the distributor to determine which coil pack to fire. Guess not.
Anyone gone through this investigation process and care to tell us what conclusions you reached?
Thanks, Dan
So, I'm looking into distributorless ignition options. I don't want to spring for stand alone engine management because of the obvious tuning and installation headaches and from what I can see, most everyone agrees they are not worth it unless you are adding all sorts of new equipment like larger turbos, MAPs, etc, and getting output up in the 350 RWH area and you can't make the engine work without one.
There are ignition kits like Electromotive's HPV-1 for $475. To me the drawbacks of that are they seem to totally ignore the Motronic ignition maps and senors and replace it with a fairly simplistic straight line map with a couple of different RPM ranges. (At least I think Porsche made a more sophisticated ignition map in the Motronic.) And it doesn't seem to incorporate knock control and boost issues.
To get to an ignition system that would seem to be sophisticated enough, it looks like you are *well* past half way to full standalone engine management in cost and installation effort.
Can't the Motronic unit tell and send out a signal which cylinder to fire without the distributor?
Does anyone, or how hard would it be to DIY, make a multi coil pack that would take the original Motronic signal to the coil and then figure out which cylinder is up? Calculate this either by the existing reference sensors on the clutch housing (or are these really not reference sensors?) or add a new crank trigger wheel?
I would think this would be a fairly straight forward deal if all you were doing is relying on the Motronic signal and then electronically replacing the distributor to determine which coil pack to fire. Guess not.
Anyone gone through this investigation process and care to tell us what conclusions you reached?
Thanks, Dan
08-05-2001, 05:51 PM
#2
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Join Date: Jun 2001
Location: Farmington,CT
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Most distributorless ignition systems use a coil per sparkplug. When a single coil is used, at high RPM (6000/7000), the coil dosn't have time "to recover" before it needs to fire again. That's why multiple coils are nice. The circuitry should be pretty simple but I don't know of commercial available systems. I don't think you going to gain that much by coverting and then all of the electrical "gremlins" are going to show up.
