CD vs. TC ignition?

[Jinksy4]

Hey!

 

Can anyone explain the difference between a CD and TC ignition system?

 

I am looking at an alternative tach and the manufacturer

 

(If you are interested):

 

http://autonnicmanufacturing.com/Home_files/Page1237.htm

 

 

said theirs would work on a 4 cycle, 4 cylinder engine if it were not a CD system. Manual says 2nd gens have a TC digital system.

 

 

Just wondering.

[Neil86]

Ventures use a TCI (transistor control ignition) where you have 12V power going to the primary side of ignition coil, and a ground going back to the igniter (ignition black box). You have current flowing back to the igniter, when the igniter needs to fire the spark plug, it opens the ground connection, collapsing the primary field, this causes the secondary (hi voltage windings) to fire the spark plug.

On a CDI (capacitator discharge ignition) the coils do not ground back to the black box....the black box sends a voltage pulse to a coil to fire the plug, and the coil boosts the voltage. Usually a CDI coil has only 1 primary wire, while a TCI has 2 wires on the primary.

The CDI black box can send up to 250+V to the coil...so be careful when working around a system with CDI.

Edited April 23, 2009 by Neil86

[Jinksy4]

Ventures use a TCI (transistor control ignition) where you have 12V power going to the primary side of ignition coil, and a ground going back to the igniter (ignition black box). You have current flowing back to the igniter, when the igniter needs to fire the spark plug, it opens the ground connection, collapsing the primary field, this causes the secondary (hi voltage windings) to fire the spark plug.

On a CDI (capacitator discharge ignition) the coils do not ground back to the black box....the black box sends a voltage pulse to a coil to fire the plug, and the coil boosts the voltage. Usually a CDI coil has only 1 primary wire, while a TCI has 2 wires on the primary.

The CDI black box can send up to 250+V to the coil...so be careful when working around a system with CDI.

 

Thanks - great explanation.