CD vs Induction Ignition
10-05-2003, 01:04 PM
#1
Guest
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CD vs Induction Ignition
Early this year Dennis Moore made the following comments about ignitions:
I'm wondering if the Crane Hi-6S (which is an induction type box) would also be a good choice. Dennis are you out there? I'd be using it with a small block (406), and feeding it the output of my tbolt IV module. Hoping to get smooth starts, a nice idle, and cleaner transom. More rpms would be nice, but I'm not expecting it.
Regards
Mike
The DUI is an induction style ignition system that has a long spark duration in the 3,500 to 5,500 rpm range (that a marine engine operates in). A CD ignition is weak at this rpm. The only advantage to a CD ignition is that the spark doesn't begin to fall off at 5,500. For engines operating at high rpm the CD ignition will not cause as much of a power loss from a weak ignition as the induction style will.
With all of the high tech electronics available for modern automotive engines you would think that at least one automobile manufacturer would install a multiple spark CD ignition on a new car but they all still use induction style ignitions.
Distributorless induction style ignition systems with a coil per cylinder are the best ignition systems available and are what the automotive industry is using on all of the new cars and trucks.
With all of the high tech electronics available for modern automotive engines you would think that at least one automobile manufacturer would install a multiple spark CD ignition on a new car but they all still use induction style ignitions.
Distributorless induction style ignition systems with a coil per cylinder are the best ignition systems available and are what the automotive industry is using on all of the new cars and trucks.
Regards
Mike
10-05-2003, 09:23 PM
#2
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I can't imagine how anyone can improve on the modern breakerless induction style ignition except for one thing. When GM came out with the automotive HEI in 1975 they made the control module with a variable dwell. At low speeds the ignition had less dwell (to extend the life of the coil) and at high speeds the dwell increased (to make a hotter spark). The Pertronix Ignitor II system has a variable dwell and I would assume that the Crane induction style ignition would also have this benefit.
An induction style ignition should be carefully matched to the coils windings ratio. There are ignition coils suited for low speed engines and ignition coils suited for high speed engines. Be sure and match the Crane ignition system with the correct Crane coil. Don't use the old style oil filled coil. Use the new style E-Core coil for maximum performance.
Increasing the amount of voltage available to the plugs is a waste of time because we need to run resistor wires and resistor spark plugs to cut down on spark voltage to prevent RFI (Radio Frequency Interference). The only improvement we can make to ignition system performance is to increase the spark duration (length of time the spark takes to move across the gap). A multiple spark ignition only does that to 3000 rpm and then reverts back to a very short duration single CD spark. An induction style ignition (with it's long spark duration) will kick a CD ignition's ass between 3000 rpm and 5000 rpm. Unfortunately you would never know it by the way the CD ignition systems manufacturers advertise their products. The GM HEI was, like most things GM, way ahead of it's time!
Sincerely
Dennis Moore
An induction style ignition should be carefully matched to the coils windings ratio. There are ignition coils suited for low speed engines and ignition coils suited for high speed engines. Be sure and match the Crane ignition system with the correct Crane coil. Don't use the old style oil filled coil. Use the new style E-Core coil for maximum performance.
Increasing the amount of voltage available to the plugs is a waste of time because we need to run resistor wires and resistor spark plugs to cut down on spark voltage to prevent RFI (Radio Frequency Interference). The only improvement we can make to ignition system performance is to increase the spark duration (length of time the spark takes to move across the gap). A multiple spark ignition only does that to 3000 rpm and then reverts back to a very short duration single CD spark. An induction style ignition (with it's long spark duration) will kick a CD ignition's ass between 3000 rpm and 5000 rpm. Unfortunately you would never know it by the way the CD ignition systems manufacturers advertise their products. The GM HEI was, like most things GM, way ahead of it's time!
Sincerely
Dennis Moore
