Martek 880 CDI box

No eBay APP ID and/or Cert ID defined in Kunena configurationI have a Martek 440 optical electronic ignition along with the companion 880 CDI booster box that I got from my dad.

I am curious about the 880. The 880 is wired in between the coil lead and the igniter, and claims to add CDI discharge spark energy on top of the inductive spark energy.

The manual can be seen in this ebay action.
i.ebayimg.com/images/g/yJ4AAOSwwD1eI1a9/s-l1600.jpg

I was bench testing both to see if they still work, using an old Z1 coil. The 440 works fine alone. When adding in the 880, the spark definitely looks and sounds stronger.

I don't really care about the 440, but I don't see why the 880 wouldn't work the same when triggered by a Dyna S. But if the 880 really works and actually does some good, why doesn't Dyna have a similar box? Does anyone else currently make a similar box? Is there any merit to this, or is it just snake oil?

Anyone have any opinions or experience on how useful the 880 might be? It's about the size and weight of a clay brick, so it would need need to be real useful to justify the weight.

Classic CDI has the advantage of higher spark voltage, but the disadvantage of short spark duration. This means you might want it for two-stroke motors where you might need to fire through oil fouling or on race engines with high compression or boost where you need the extra voltage to initiate the spark. But the down side is that idle can be less stable with that short duration.

Classic transistorized Kettering (on most Kz's after 1980) , also sometimes called "inductive", has a longer duration so is really good for smooth idle, but doesn't have the extra voltage for really high compression or boost.

One way to get the benefits of both is to use MSD which is CDI but it fires multiple times in rapid succession at lower RPMs.

Another way is that Martek device, which apparently fires a CDI discharge just before the inductive discharge.

Generally speaking, if you can open up your plug gaps about 20% and still get reliable firing at high RPMs at WOT, you probably don't need the CDI advantages and probably won't notice any difference in running. Running wider gaps greatly stresses the coils and igniter, so you don't want to run that way permanently unless the coils and igniter are both rated to handle it.

I've been poking around trying to find something similar. The only thing I've come up with is the Pertronix Second Strike.

www.pertronix.com.au/second_strike_ignition_system.html

How would I got about actually testing the 880, given that I don't have an engine dyno?

I'd first need a way to trigger it at the equivalent of 9000 RPM. I guess I could mount the trigger rotor on my dremel tool.

But then what? How do I measure or observe the spark energy or effectiveness?

Do I need to build/buy something like this:

To boil it down, maybe a little too much...

For smoothness of idle, you want to measure a spark's duration. This can be seen easily on an oscilloscope, and pretty precisely, as long as a lot of steps are taken to protect the scope from the high voltage damage (I had to order some nearly impossible-to-get parts from Israel for the Tektronic scope at work, so beware, it's easy to blow up the input circuit of a scope!).

For high RPM power (via a larger plug gap and compensated timing), you can just try to jump a larger gap in open air. This is basically a voltage test, but measured in distance rather than voltage. However, to test this you risk damaging the ignition or coil. A decent coil should easily jump a 3/4" gap. By the time you reach 1 inch you might be doing minor damage to the internal insulation. Only push it near 1 inch if the coil AND igniter are both advertised as delivering way more voltage than a normal ignition. Some coils can survive quite a bit more stress than expected on a stock engine, and some can't.

If you really need to know the actual energy for some reason, you can look at a scaled-down version of the spark voltage curve on the scope.

If you put a known resistance in the path of the spark current, you could use a scope to measure the voltage on the resistance and get a curve for the current in the spark.

From the voltage curve and current curve you can calculate the energy. This will probably be a very inaccurate estimation though.