The V8 Owners Forum -

Eliot wrote:What problems are you actually experiencing?
Fitting mega doody funky blaster coils and all the other related stuff such as 1" ignition leads (I'm exaggerating) is only really making up for the fact that a single coil on a v8 engine doesn't really have enough time to charge at high rpm to give a decent spark.

Hi Elliot, You are correct in that it takes time to saturate a coil and there ain't much time between firing points on a V8 with a single coil.

It takes much less time to charge a capacitor compared to a coil which is handy if you run a capacitor discharge system such as an MSD.

sidecar wrote:

Eliot wrote:What problems are you actually experiencing?
Fitting mega doody funky blaster coils and all the other related stuff such as 1" ignition leads (I'm exaggerating) is only really making up for the fact that a single coil on a v8 engine doesn't really have enough time to charge at high rpm to give a decent spark.

Hi Elliot, You are correct in that it takes time to saturate a coil and there ain't much time between firing points on a V8 with a single coil.

It takes much less time to charge a capacitor compared to a coil which is handy if you run a capacitor discharge system such as an MSD.

Not sure I agree with that. I don't see why you can't design a coil to charge sufficiently between sparks. If you can design a capacitor, why not a coil?

Clearly in the old days you had other issues, like if the ignition was switched on, but the engine not running, and the points closed, you didn't want the current flowing through the coil to set it on fire (so you had a relatively high DC resistance).
But with modern ignition amplifiers, that scenario disappears, so you can design the coil with a very low DC resistance.

And one thing you don't want to do is saturate the coil. If you do that, the current shoots to infinity (well, the current is set by the DC resistance, not the inductance at this point), and you blow up your amplifier / points!

Chris.

You can you just multiply them i.e wasted spark, coil on plug ign etc

ChrisJC wrote:

sidecar wrote:

Eliot wrote:What problems are you actually experiencing?
Fitting mega doody funky blaster coils and all the other related stuff such as 1" ignition leads (I'm exaggerating) is only really making up for the fact that a single coil on a v8 engine doesn't really have enough time to charge at high rpm to give a decent spark.

Hi Elliot, You are correct in that it takes time to saturate a coil and there ain't much time between firing points on a V8 with a single coil.

It takes much less time to charge a capacitor compared to a coil which is handy if you run a capacitor discharge system such as an MSD.

Not sure I agree with that. I don't see why you can't design a coil to charge sufficiently between sparks. If you can design a capacitor, why not a coil?

Clearly in the old days you had other issues, like if the ignition was switched on, but the engine not running, and the points closed, you didn't want the current flowing through the coil to set it on fire (so you had a relatively high DC resistance).
But with modern ignition amplifiers, that scenario disappears, so you can design the coil with a very low DC resistance.

And one thing you don't want to do is saturate the coil. If you do that, the current shoots to infinity (well, the current is set by the DC resistance, not the inductance at this point), and you blow up your amplifier / points!

Chris.

Hi Chris,

A coil and a capacitor are different devices and they work in different ways.


A. G. Bells book on four stroke (and maybe his one on two strokes) has several pages on CDI systems and compares them to systems that store their charge in the coil.

Years ago I could have explained it better when when I was taught a load of gumph about electronics at uni but as I never used the knowledge it has drained away out of my brain!

Here is a link that talks about the coil becoming fully saturated..."CHARGE TIME , VOLTAGE RISE TIME , SPARK DURATION".....

http://www.jetav8r.com/Vision/Ignition/CDI.html


CDI systems do have a short spark duration which is one reason why they sometimes have mulitple sparks per firing stroke. (MSD)

Cheers,

Pete

I use Megajolt Light as well. Mapped on rolling road. Kit supplied by Trigger Wheels.
Regards,
Miel