Bought a Bosch GT40 ignition coil 'bout a year back. Being heavily involved with electronics I thought I,d check the thing out against a standard 12 volt coil to see what they altered. Somewhat surprised I found the primary ( 12 volt side) and the secondary ( ouch side) to have all but identical resistances and inductance. I would have expected to find lower impedances on the primary at least. I very much suspect the biggest change here is the colour of the sticker!. John
Conned I think
Feb 27, 2009
2 Replies
Dear John (and the Newsgroup),
The amount of energy you can use in your ignition circuit is determined by the amount of energy the swtich can handle. If you need more energy you would need LARGER POINTS to carry it.
I explained this in 1994, shortly after I began posting VW-specific messages to the internet. But with the VW magazines insisting a blue coil was 'hotter," any attempt to inject a whiff of reality was brushed aside.
-Bob Hoover
Bob, Spot on. Should also mention the current drain /current rise times of GT40 "in circuit" was also almost exactly the same as the standard coil.. Same energy in = same energy out. I suspect if the primary was designed to take more current to give you the higher energy output a firm like Bosch would have recommended a transistor assisted ignition to avoid having ignition points burning out every couple of months. Wonderful thing placebo effect ,eh. Hope everything is going as well as it can with yourself. John
Join the Discussion
Have something to add? Share your thoughts — no account required.
Didn't find your answer?
Ask the community — no account required