Originally Posted by Neil Harvey (Post 11334385)

I always try to stay out of these discussions as I am an engine person, not an electronic guru.

I have always deferred to Wayne at M&W for Ignition advice over the past 25+ years.

In reading all of the posts here, there is something missing. Something way more important TO ME!!!!

No disrespect meant to you Fred, but you are always missing the most important number in any of your posts, TO ME!!! THATS ENGINE TORQUE produced.

As an engine person, I could care less what the internals have, I want to see a torque increase on the dyno, driver response on throttle response and reliability.

An engine is the sum of its parts. I want the best parts possible in every area of the engine. If the
CDI I choose produces more torque in testing, and is reliable, I'm buying that one. That is job #1.

Wayne has always come through for me on every system we have purchased from him and we have found in over multiple engines, the CDI system we use produces the most torque in all of our testing.

Our name is Performance Developments so developing performance is our DNA. Spark plug life is not important to us. Plugs are cheap!!!!!

These large chambered engines with domed pistons, ports that do not flow well, have a lot of reversion and messy air flow when the throttles are opened, need all the help they can get. The ignition is the last event to happen, so make it worthwhile.

To me, reading all about the testing that has been done, is all too much about the "pointed hat" syndrome.

If you want to sell your Ignition system to engine people, sell them engine performance gains.

That is what Wayne sells to me.

Originally Posted by Fred Winterburn (Post 11334225)

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

Originally Posted by dannobee (Post 11334791)

I'll ask again, what modern car(s) use CDI? In the last 10-15 years?

I'm not saying that everything used by major manufacturers is the "best," but they do have to meet emissions and reliability standards, along with performance standards, and are consistently judged by their consumers and competition. There must be reasons why they choose the ignition systems that they do.

Originally Posted by M&W Ignitions (Post 11334763)

Fred

We are a small company specialising in high reliability and performance cdi systems from 115mJ up to 2,000mJ. Between us we have 80+ years experience with over 10,000 cdi systems sold and that quantity again of inductive modules although we no longer make these. Our early designs used a continuous mode flyback transformer and conventional scr technology however due to their limitations this was quickly changed to quasi resonant transformer drive and high side firing IGBT’s which, with their significantly improved electrical characteristics, allowed us to turn away from conventional cdi theory.

Our ‘experiments’ as you kindly put them consist of real world testing on AVL / Kistler instrumented Australian, European and US engines both single and multi cylinder. We do have spark gaps, pressure chambers, Zenner strings and a plethora of other ignition specific equipment however test bench experimentation often doesn’t equate to in cylinder results. Using new theories we were able to find noticeable improvements in engine power/torque and an increase in fuel mixture tolerance using a completely different ignition profile to your proposal. So far this has held true for all fuel types tested including gas (LPG), petrol, alcohol and nitromethane.

Yes you can reduce plug erosion by altering the discharge characteristics however we are a performance company therefore to do so is contra indicatory.

When you say ‘a few corrections’ and ‘indeed facts’ this assumes your point of view is the only valid one however perhaps it would be wise to consider nothing absolute as new discoveries are made every day on subjects once considered final. About the only similarity between our designs and those of you and your late father is that they both discharge a capacitor into a coil.

M&W stands for Mark & Wayne

Originally Posted by dannobee (Post 11334791)

I'll ask again, what modern car(s) use CDI? In the last 10-15 years?

I'm not saying that everything used by major manufacturers is the "best," but they do have to meet emissions and reliability standards, along with performance standards, and are consistently judged by their consumers and competition. There must be reasons why they choose the ignition systems that they do.

Originally Posted by Speedy Squirrel (Post 11338505)

tripling or even quadrupling the inductance of the systems

Originally Posted by Speedy Squirrel (Post 11338505)

Keep in mind that it is the temperature of the spark that ignites the mixture. That temperature is produced by ionization energy from the ignition, and once you get to that temperature, more energy doesn’t do anything. The inductive ignition can keep the ignition temperature hotter for longer than CDI, but CDI can also provide multiple discharges in some conditions to narrow that benefit.

Originally Posted by Speedy Squirrel (Post 11338505)

A problem with CDI on a modern engine is that the intensive refinement of shift behavior, traction, emissions, and fuel efficiency is produced in part by slewing the spark rapidly between operating points. You would have to have a CDI with multiple capacitors to get the slew rates that an inductive COP system can produce easily.

Originally Posted by M&W Ignitions (Post 11339301)

Let us start out by stating cdi ignition is not for every application or for every person. Both inductive ignition and cdi ignition have their purpose and you can not state without qualification one is better than the other. Also remember we are a performace oriented company therefore do not get involved in unmodified factory vehicles.



Huh! Dont remember the last time we measured a COP style coil which has more inductance than an external coil, generally they tend to have less inductance due to restricted room for windings and little to no room for the magnetic core.



Here you are getting back into the old myth about longer arc duration being more optimal which has been proven false in many scientific papers. As per an earlier message the ability to ignite fuel is 'EI' Energy multiplied by Time. If you lack one you need to make up with a lot of the other. Multi discharge is also useless except in very limited circumstances as the crank has moved too far between sparks at anything much above idle. Multi dischage is used by both cdi and factory inductive ignition to help solve cold start emission issues on some modern engines.



Not sure where you are coming from here, that does not make any technical sense to us what so ever.

CDI ignition can be ready to fire the next spark in less than one third the time of the fastest inductive ignition system and is superior in dealing with agressive timing changes and firing interruptions than inductive ignition. CDI ignition is edge triggered and automatically recharges for the next event after firing unlike inductive ignition which requires a precisely positioned leading dwell period to prepare for the next firing event.

Originally Posted by Fred Winterburn (Post 11339376)

I would like to know the absolute reason why CDI is not used in a COP system anymore (other than Saabs older system).

Originally Posted by M&W Ignitions (Post 11339462)

Fred

It is not used mainly due to cost and service interval. There is another not well understood problem with COP/Pencil coils when used with cdi ignition due to their less than ideal magnetic properties (simplified) although we have noticed recently the changes to Bosch pencil coils which should reduce/eliminate the problem.

SAAB used cdi originally as it allowed them to more easily implement spark plug ion current monitoring for knock detection however now there are a number of inductive ignition coils with this feature built in such as those used by Haley Davidson.

Originally Posted by M&W Ignitions (Post 11342262)

Nice looking coil you built, what leakage inductance were you able to achieve?

Originally Posted by Jonny H (Post 11342841)

The coil geometry is similar to the original Bosch black coil so leakage should be similar also.

Originally Posted by Jonny H (Post 11342841)

Being a high voltage pulse transformer, the dominant factor is the insulation.

Originally Posted by M&W Ignitions (Post 11343388)

That could turn out to be a very expensive and dangerous assumption. There is a company known for their Almost Engine Management who attempted to copy the much used Denso pencil coil with absolutely disasterous results. That coil went on to damage more ignition systems in the world than you could possibly imagine.



For the coil maybe but not the ignition system.

Originally Posted by dannobee (Post 11332389)

I know that one of the limitations with inductive ignition systems has always been the dwell time because of a single coil.

Originally Posted by dannobee (Post 11332389)

Did ALL of the manufacturers shy away from CD ignition systems because of cost, or are there other variables in play?

Originally Posted by dannobee (Post 11332389)

Since we're Porsche specific here, when was the last Porsche CD ignition system used?

Originally Posted by dannobee (Post 11332389)

Wasn't it in '89?

Originally Posted by dannobee (Post 11332389)

Why did they quit using it?