Jeff,
I could go on forever. I have never tested an M&W CDI. I certainly agree with M&W on mJ outputs as those numbers are almost meaningless unless the whole package is considered. My R&D budget is pretty small but I have managed to find things through experimentation that aren't so well known. The only modern CDI that I have run on a car and which isn't so modern anymore was an Accel 300+ digital CDI. It needed more than 10V to operate so I had to run it off a dedicated battery while the engine was cold and on the starter. It was indeed hard on the distributor cap and the plugs. The rest of my experience and research is mainly entrenched in what was built during the sixties for historical reasons. I have tested and have quite a few in my collection now from various manufacturers. Half of these infringed on my father's design from 1962 (patent filed 1963) which in 1963 became the Hyland CDI (I have no idea why it was called Hyland). Sydmur, Tiger, Delta, Speedatron, VJ Products , Magnetti Marelli AEC101 were amongst those that infringed. VJ Products was the only company to pay royalties. An interesting one that didn't infringe was the Tung Sol(Motion) EI-4. They were in production before my father's but are tube type. A spark duration of only 3µS and being tube type, not destined for a long life. I have two of those in my collection now, one a positive ground unit and the other negative ground. Those units are something to behold. I also have several Hyland units and they were made cheaply to keep costs down, although they were quite reliable. A Tung Sol CDI cost $120USD in 1962. The Hyland was first solid state CDI to be put into production and it cost $35 in 1963. My father had been building CDIs since the early fifties using thyratrons but those kept failing in just a few months so when the SCR came along he latched onto it. Another interesting one built about 1966 and the first to use the Theodor Sturm patent (filed just a few days after my father's patent), made in San Diego, was the Blitz Funken. The Blitz Funken predates the Permatune that also used the Sturm patent. And yet another one I have that must date from the late sixties is called the Hot Box and has a knob that can adjust the rev limit. It was made in Seattle area and I'll bet no more than two or three were made. Quite badly done and the rev limiter doesn't work well at all but also a neat piece of history. Another really interesting one is the Compu Spark that Tom McCahill pushed for years in magazine advertising. It is a true double spark CDI with the sparks coming 200µS apart which is quite a useful separation (MSD is 1mS). The only modern equivalent to the Compu Spark would be Jonny Hart's CDI+. Mine multi-sparks differently and longer if the right coil is used. I'm looking for a Stevens CDI to add to the collection but doubt I will ever find one. They were very powerful, expensive, but were meticulously voltage controlled. And of course I have a couple of MSD 6As that I play with from time to time. The problem with most CDIs is that either they have no voltage control or the voltage is way too high for longevity in distributor type street cars. The worst in my collection is the Hot Box that uses an old filament transformer oscillating at 50Hz. It puts out up to 70 thousand volts at idle but runs out of steam quickly to no more than 12 thousand volts at 333 sparks/s.
Anyway, After my Dad passed away, I decided I wanted to make a few using his design for my old cars, but they needed to look good so I decided if I was going to that trouble I might as well sell a few too. So I developed one with a longer duration, and compatible with either positive or negative ground (without any switches or wiring changes). Every one I make now is basically a copy of the final prototype. Labour intensive construction techniques. The power supply is different than the old Hyland and unique from any other in a few ways. It's not a Royer variant like most of the old supplies either. It has two supply transistors but will run handily with just one up to a certain rpm. To date I have built just under 250 units in 7 years and expect I will quit this hobby in another two or three years so I will have time to restore my old cars and keep up with chores on my country property. Just got an email yesterday from a fellow with an Austin Healey. He reported that his gas mileage went up by 20% with the CDI. That kind of report makes me feel good about the product and my take on my father's old design. Old fashioned it may be, but it still does the job, and does it rather well. Fred
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Originally Posted by Jeff Alton
Great discussion. M&W has a great reputation for many years. Different test yield different results. Fred, what products have you used, developed or tested? Give some background as this is a great discussion. And thankfully, it has not gone down the swirling water in the porcelain fixture like many other threads have recently... 
Thanks |