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Old 12-24-2012, 10:04 PM   #282
58mm of Bliss
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Join Date: Jul 2003
Location: PEI,Canada
Posts: 4,369
My Ride: 330i, 330Ci
Originally Posted by Commanderwiggin View Post
I'm not sure I'm picking up what you guys are talking about to discuss further? What I'm getting from this is on a turbocharged application you are doubling the amount of work required from the coils? Or is this in regards to different EMS running the coils?
I'm going to word this to focus on the facts, not a specific product:

If an EMS doesn't have enough ignition outputs, or the software/processor configuration doesn't have the ability to run X ignition outputs sequentially, you can run a "wasted spark" configuration.

This is provided that the engine has an even-fire bank configuration, where for example cylinder #1 on bank A is at TDC at the same time as cylinder #3 on bank B.

Wasted spark on a 6 cylinder engine would use 3 ignition outputs that fire every 360 degrees of crank rotation. In a sequential configuration, 6 individual outputs would fire once every 720 degrees.

Or in other words, every time a piston is at TDC, the ignition fires with wasted spark. Half the time it's igniting a burn cycle, half the time it's firing during the exhaust cycle.

Sequential ignition outputs would fire only during the burn cycle.

So with "wasted spark", you gain the ability to fire more cylinders, but the ignition system effectively doubles the work load on the existing hardware. It has nothing to do with the fact than an engine is turbo charged or not.

The other miss-conception about FI engines is that running more boost puts more load on the ignition system. This is not true. The ignition system doesn't care about cylinder pressure, or whether the signal output to the spark plug does it's job. It just keeps doing it's thing blindly. If the system doesn't have enough strength to light off a high pressure cylinder charge, it's actually easier...because the energy doesn't get expended. (Missed ignition) That's not to say that more cylinder pressure doesn't need a stronger ignition system, because this is usually the case. It's just that as far as load goes, or how much work the ignition does, system life is a function of RPM or simply how many times the system fires, not so much what it's firing into.

Man...I really should write up an article on smart coils, dumb coils, ignitors, and CD systems.

Last edited by PEI330Ci; 12-24-2012 at 10:05 PM.
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