Replacement CDI Unit

[RDM]

Originally Posted by Raceboy

Excellent information? What exactly? Just telling that product x is better because we say it is better? I still have not seen any valid proof why and how it is better.
I have no dog in thos race but tbh mysocal911 has provided real and tangible data on spark properties (and to be fair, Fred has also, with valid arguments) but saying just "we as engine builder say that it is good" is just nothing but hot air.

I am willing to give my twin plug ditsributor to the guy who succeeds to prove that I get real life more torque and power when switching from VEMS controlled inductive ignition (with proper coils of course) to CDI ignition.

There's more than one way to tell the truth of information. One is by charts, graphs and numbers. Another is by the character, reputation and accomplishment of the messenger.

Maybe you need charts and graphs. That's fine. I don't. I've read enough posts by Neil and Jonny to have an idea of their character. Loren/Dave/socal as well. No need to cast aspersions on the providers of the information, or those who appreciate it. We have a different perspective; leave us to it.

[Raceboy]

What if Aston Martin Racing (Prodrive) engine tuner (who has tuned all the recent years GT3's, including Le Mans 24hour race class winner car) tell you that unless you use methanol or some other fuel that is difficult to ignite, you get no gains provided that current ignition system is in good working order?
I happen to know him very well personally, we are both engine management tuners.
But do not let that kind of information distract you and keep on believeing what you want.

EDIT: All Aston Martin race cars use COP inductive ignition not CDI. Would they use CDI if there are any gains to be had? Not that they are budget limited in that kind of crucial area

[Jonny H]

Originally Posted by Raceboy

What if Aston Martin Racing (Prodrive) engine tuner (who has tuned all the recent years GT3's, including Le Mans 24hour race class winner car) tell you that unless you use methanol or some other fuel that is difficult to ignite, you get no gains provided that current ignition system is in good working order?
I happen to know him very well personally, we are both engine management tuners.
But do not let that kind of information distract you and keep on believeing what you want.

That is a ridiculous generalisation. If that statement were true there would be no point in twin plugging a 911 engine. A lot depends on the design of the combustion chamber.

It might be of interest that McLaren list both Inductive and CDI COP coils in their current lineup of parts.

McLaren Applied Technologies

[Raceboy]

Twin-plugging is totally different solution to a totally different problem. It is needed because of physical placement of spark plug and since flame fron travels at more or less constant speed (depending on fuel, atomization etc but lesser amount) having second plug reduces ignition advance requirement.
For example on 4valve heads where plug is in center position the problem is solved because that is the best place for a spark plug and it is shortest distance for the flame front to travel.

But that does not apply to CDI vs inductive because CDI does not accelerate burn rate.

My standing on this remains the same: unless inductive system has some issues with misfires (and that includes ever so slight ones that happen randomly on single cycles and are pretty much not felt) or one does not use some heavy fuel like methanol or nitromethane, there is no direct gains in power to be had.

Is CDI better than worn out inductive or CDI system? Of course. But not necessarily compared to the system that is up to its task.

For any factory production car (even Porsche, Ferrari etc) it is totally valid to reason the use of inductive system just due to cost per unit, but with factory race cars that logic does not apply. They use what they consider the best there is. And I would like to find out which factory race cars use CDI.

[m42racer]

Race bouy,,

You are a strong user of Inductive Ignition. That is great that you so much passion for that type.

But others with far more experience and knowledge than you have, have found in their independent testing that CDI is superior when used with Porsche 911 2V engines.

In reading their posts, they have not said you are full of crap, nor have they said that Inductive is crap. They have just stated that in their testing and research, what they have found. You come along and demand dyno sheets to prove what they have found. They don't have to prove anything, especially to someone like you who has no history, no experience or motorsport background to even come close to some of the experts on here.

You make yourself look really stupid when you challenge people with lots of experience and knowledge and you do not have the background to match.

Credibility counts my friend.

Many people use Inductive on the Porsche 911 2V engine. No one here has said that it is wrong. Just what they have found.

State your findings and allow others to state theirs without challenging them.

[Raceboy]

Are you challenged or what is your problem with spelling? Can you make a difference between brake and break? Their and there?

How the hell you know my experience? What kind of experience you have with tuning engine management systems? I would really like to know. For me you are just a nobody who believes in things but fails to provide any valid points (believe me (pun intended), "I trust" is not a valid point).


Providing valid techincal arguments and waiting for opposing side to do the same is stupid? I think you have really wrong idea of how debates go.
All that chit-chat and yet I have not heard/read ANY valid arguments why CDI is better on 911 2v heads. Nothing.
All that talk about "we have found", "they have found", "we trust", "we believe" etc but nothing technical.

I explained why twin-plugging is beneficial (and no, it is not related to CDI in any way lol) in technical terms not just BS like "I believe", now I would like to hear arguments why CDI would bring gains in torque+power on 911 2V engines.

I will happily wait and read and hope to find out something me (and some of the best tuners on the planet) have not yet found out.

And in the meantime you can stop diminishing me and my nickname, you should also try to learn something instead of blindly believing. I have tuned more engines during 20 years in the than you can imagine so give yourself a break and stop worrying about my expertise in that field.

Originally Posted by m42racer

Race bouy,,

You are a strong user of Inductive Ignition. That is great that you so much passion for that type.

But others with far more experience and knowledge than you have, have found in their independent testing that CDI is superior when used with Porsche 911 2V engines.

In reading their posts, they have not said you are full of crap, nor have they said that Inductive is crap. They have just stated that in their testing and research, what they have found. You come along and demand dyno sheets to prove what they have found. They don't have to prove anything, especially to someone like you who has no history, no experience or motorsport background to even come close to some of the experts on here.

You make yourself look really stupid when you challenge people with lots of experience and knowledge and you do not have the background to match.

Credibility counts my friend.

Many people use Inductive on the Porsche 911 2V engine. No one here has said that it is wrong. Just what they have found.

State your findings and allow others to state theirs without challenging them.

[mysocal911]

Originally Posted by Jonny H

The tests clearly show improved torque over a standard CDI box with no change in timing. As Fred stated earlier, voltage plots don't tell the full story.

So what is it that's unique about the differences in the spark over a stock CDI or an inductive
discharge spark that results in more torque? One just can't make such a subjective implication
without analyzing the spark differences even though dyno results may indicate an improvement,
i.e. an analytical approach is needed to prove or disprove the hypothesis - different ignitions
produce more torque. The basis for different outcomes needs to be fully explained and correlated
to the changes in the input variables, i.e. the ignition type used and its unique spark.

As an example we can relate to, why is it that some late model vehicles will show better
performance with higher octanes than others? Some may conclude that based on a subjective
analysis, all vehicles should use a higher octane, i.e. the octane itself made the difference.
But once a thorough analysis of the two vehicles is done, one finds that one vehicle's engine has
a higher compression ratio and its knock control system has retarded its spark with the lower
octane fuel, where as that didn't occur on the lower compression engine in the other vehicle.

If the differences in outcomes can't be fully explained analytically, then the conclusions,
e.g. dyno results, are suspect as is the case with comparing ignition systems. Another unknown
variable has caused the possible different torque values and not the differences in the spark
signals themselves of the different ignitions.

[mysocal911]

Originally Posted by m42racer

But others with far more experience and knowledge than you have, have found in their independent testing that CDI is superior when used with Porsche 911 2V engines.

Then why did Porsche with the 911 3.2 switch to an inductive discharge ignition system in 1984?
That engine still had a distributor and continuing to use a CDI, as in the '83 911SC, would have
been easy, if a "CDI is superior when used with Porsche 911 2V engines." as you state.

[Jonny H]

Originally Posted by mysocal911

Then why did Porsche with the 911 3.2 switch to an inductive discharge ignition system in 1984?
That engine still had a distributor and continuing to use a CDI, as in the '83 911SC, would have
been easy, if a "CDI is superior when used with Porsche 911 2V engines." as you state.

Emissions and cost.

[Jonny H]

Originally Posted by mysocal911

i.e. the ignition type used and its unique spark.

You dismissed our 'unique spark' in a previous post. Our rapid (400us) 'double' spark is what makes the difference in power. This is not a new idea and is in widespread use in modern cars.

Many vendors now offer 'multi charge' ignition systems to optimise combustion.

For example:

https://www.delphi.com/manufacturers/auto/powertrain/gas/ignsys/multi_crg_ign

This is my last post on this matter.

[mysocal911]

Originally Posted by Jonny H

Emissions and cost.

1. OK, now you've indicted a CDI disadvantage, i.e. higher emissions which imply less complete
combustion and thereby less energy release from the fuel charge - less torque then too.

2. If it produces more torque for a 911 2V motor, no 911 3.2 racer that I've seen has switched
to using a CDI system.

3. Performance over cost was prioritized for the 911 3.2. So if a CDI was really beneficial,
Porsche/Bosch would have used it versus the inductive system. Using the DME ECM with its O2
sensor and CAT on the 911 3.2 would have solved any potential emissions problems with using
a CDI system.

[Jonny H]

Another happy customer. Down the page a bit, green '69E outside the pub. Lovely car.

DDK - Die Deutschen Klassiker β€’ View topic - What did you do in/on/for your Porsche today?

[mysocal911]

Originally Posted by Jonny H

You dismissed our 'unique spark' in a previous post. Our rapid (400us) 'double' spark is what makes the difference in power.

As noted before, the second spark is too narrow and of marginal energy to be of any benefit.

Originally Posted by Jonny H

Many vendors now offer 'multi charge' ignition systems to optimise combustion.

For example:

https://www.delphi.com/manufacturers/auto/powertrain/gas/ignsys/multi_crg_ign

And they are using an inductive discharge system to achieve the desired spark energy levels
and to develop very short intervals been the multi-sparks.

[Fred Winterburn]

Dave, Your assumption that the second spark is of no benefit can be easily disproven by looking at other CD ignitions that have worked successfully. For example, I have a vintage Tung-Sol (Motion) thyratron CDI that has a very typical looking two phase spark. What isn't typical is the duration, which happens to be only 3΅S long (yes, only 3 millionths of a second for both sparks) and a total available spark gap voltage of a modest 30kV. Yet those CD ignitions were used on racing Corvettes with success. Lots or corona a radio noise too, but that's another issue. Fred

Originally Posted by mysocal911

As noted before, the second spark is too narrow and of marginal energy to be of any benefit.




And they are using an inductive discharge system to achieve the desired spark energy levels
and to develop very short intervals been the multi-sparks.

[m42racer]

Hey,

Race boy/Dave-Loren,

You guys are such turn off's, I'm done. I believe what I want to believe and do not need some smart """ telling me what I should believe and what i shouldn't.

I choose to believe those that know what they are talking about. Those that know what they are talking about typically listen to what others have to say in the event they may learn something. They are not aggressive in their questioning and it becomes clear what they are talking about in how they behave.

When you and the other """" come across so aggressively, I for one turn off. I could care less what you have done in the past, as I doubt very much you have any real experience or knowledge. If you did, you would have come to the same conclusion as these other experts have.

Have you bothered to stop and think, there are more experts on here that have come to the same conclusion. Look at who they are? Two make CDI units, maybe because they know what they are talking about and have found that it is the best ignition for these engines. The other person is way out of your league so I suggest you don't even try to go there.

I thank the real experts that have come on here to offer up their expertise and knowledge for all of us, for free. I have learned something.

This has turned into how every other thread has, when these two jokers get involved. They just cannot stand to be wrong.

I'm sold on CDI. Not only on what you CDI experts have stated, but on how you have conducted yourselves in a professional manner.

[Raceboy]

Originally Posted by m42racer

Hey,

Race boy/Dave-Loren,

You guys are such turn off's, I'm done. I believe what I want to believe and do not need some smart """ telling me what I should believe and what i shouldn't.
When you and the other """" come across so aggressively, I for one turn off. I could care less what you have done in the past, as I doubt very much you have any real experience or knowledge. If you did, you would have come to the same conclusion as these other experts have.

Have you bothered to stop and think, there are more experts on here that have come to the same conclusion. Look at who they are? Two make CDI units, maybe because they know what they are talking about and have found that it is the best ignition for these engines. The other person is way out of your league so I suggest you don't even try to go there.

I thank the real experts that have come on here to offer up their expertise and knowledge for all of us, for free. I have learned something.

This has turned into how every other thread has, when these two jokers get involved. They just cannot stand to be wrong.

I'm sold on CDI. Not only on what you CDI experts have stated, but on how you have conducted yourselves in a professional manner.

Are you thick or what? I already told you, feel free to believe what you want. But with your belief (like many other "believers" like in religion), you ignore facts and bash others who you have no **** idea who they are.

I asked you, how many cars have you tuned? You couldn't even answer a basic question regarding ignition system => you are too dumb for this topic to even have slightest idea how to filter out opinion from fact.

I also have asked very specific questions that I did not get any answer to. I only got BS round talk like "we believe", "I have found" and that's it. I provided facts where people have in contrary NOT found any gains and these are ignored.

Now can you please stay away from technical discussions that relate to engine control because clearly you have nothing technical to provide, you are only able to provide personal insults. Calling me a clown? Go and read a bit about systems and then you can perhaps have sonme clue what people talk about.
I know very well who they are, but clearly you haven't got a slightest idea that there may be other experts in the field also.

Tired of this salesman mentality where few guys sell something claiming it is best thing since sliced bread and yet fail to answer a simple question that I asked several times:

now I would like to hear arguments why CDI would bring gains in torque+power on 911 2V engines.

[mysocal911]

Here's a graphic plot provided by Classic+ of a dyno of the CDI+ versus a Bosch CDI:



As can be observed (lower 2 plots), once the RPM are over 2,500, the difference in horsepower (HP)
between the two curves is negligible. Below that RPM, the difference can be explained by the different
circuitry used on each units' inputs to trigger the spark output. The Bosch unit uses a discrete circuitry
Schmitt Trigger circuit which requires a higher input voltage (delayed trigger - retarded spark)
than the CDI+, which uses a LM1815 IC to process the negative going distributor's reluctance
voltage signal. If a lower negative distributor input signal is sensed by the CDI+ at lower RPMs
to trigger a spark, the result will be a small advance resulting in more HP below 2,500 RPM.
In summary, the CDI+'s second spark contributed basically no increased HP.

[Fred Winterburn]

Dave,
Odd, I just looked at the CDI+ website and the testing team took into account variations in timing and ran tests with the CDI plus slightly retarded to compensate. Anyway, I would agree that a second spark occurring too late would have no benefit (like MSD with a full milli-second which might as well be occurring in another time zone let alone the same cylinder it is so late), but I believe 200 to 400΅S would have some benefit.
I won't be posting any of my waveforms here. Too complex and open to complete misinterpretation, since the coil inductance plays a huge part in spark shaping. It took me a long time to figure them out. For instance, after the initial negative strike, there is always a positive spark, but if the coil is a good one and the secondary side resistance is lower than 30 kohms, there is no re-strike, so no voltage peak as the gap is still ionized sufficiently. If there is a re-strike, the next negative spark will (usually) also have to re-strike. If there is no need to re-strike, the peaks are low and fat. In one scope picture, one could easily misinterpret the spark as having one negative strike, followed by 3 positive strikes when in fact the spark was also negative in the cycle. Open up the spark gap and the negative peaks start to show up again. At times, the spark is quasi-inductive in nature because of the system's dependence on the coil inductance for multi-sparking. In short, only a trained eye that has manipulated those waveforms can guess what is going on. Fred

Originally Posted by mysocal911

Here's a graphic plot provided by Classic+ of a dyno of the CDI+ versus a Bosch CDI:



As can be observed (lower 2 plots), once the RPM are over 2,500, the difference in horsepower (HP)
between the two curves is negligible. Below that RPM, the difference can be explained by the different
circuitry used on each units' inputs to trigger the spark output. The Bosch unit uses a discrete circuitry
Schmitt Trigger circuit which requires a higher input voltage (delayed trigger - retarded spark)
than the CDI+, which uses a LM1815 IC to process the negative going distributor's reluctance
voltage signal. If a lower negative distributor input signal is sensed by the CDI+ at lower RPMs
to trigger a spark, the result will be a small advance resulting in more HP below 2,500 RPM.
In summary, the CDI+'s second spark contributed basically no increased HP.

[Neil Harvey]

This turned ugly quick.

This forum is for car owners who wish to do a lot of their own work, come on here for advice and knowledge. If we as pros wish to contribute, we should do so in the spirit of this forum.

Who cares what the scope traces look like, or how the ignition 'works". Really?

I'm a user of ignition just the same as the end user. I want something that is reliable and won't leave the owner stranded on the side of the road. If it gives some added benefits more the better.

I can understand the theory, but that should be for another forum. Where all "pointed headed geeks" can have their say. Here I believe if we wish to repair, sell or supply any part to the DIY community, it should be kept with the spirit of the forum and information given and not challenged in the open. We should be informative and as companies identify what the DIY owner actually needs in an ignition system. Is it because they want more power or is it because they want a unit that is reliable. I'll bet every penny for a dollar its the later.

Who cares if CDI is better than Inductive when it deteriorates down to the level this has gone. I can tell you we prefer CDI in the Porsche 911 engine with the hemi chamber. That does not mean that Inductive will not run the car. Our testing results are private and we do not throw them around in an effort to sell anything. When it comes down to "show me your dyno results or you are lying" the whole point of helping the DIY is lost. Get real, its not about dyno results but credibility, both product and company.

We test all products we sell and they all have to meet our quality standard. Both the units we sell do this in excess and both have their own advantages.

I have never had one customer call and ask, does your CDI unit make more power than this one? Show me your Dyno results? Everyone asks, is it reliable and will it leave me stranded. That you can take to the bank!!!!

This argument over CDI verse Inductive is never going to end. As a engine engineer (with a little experience) I can tell you both have their place. We use both. But one is better suited to certain applications in our opinion. That's it.

[Fred Winterburn]

Now, I disagree that it only has interest for 'pointy headed geeks'. I vaguely resemble that remark. So, I've changed my mind. Here is a scope trace I did today. I should have wiped the grime from the scope, but the image still works. The test was done with a cheap Standard brand 12V canister coil with a primary resistance of 3.5 ohms. 14 volts applied to the CDI, and 22 kV spark gap. Secondary side resistance approximately 15 kohms. The voltage peaks are not as high on trailing sparks as the first negative spark since the gap is partially ionized after the first spark extinguishes. Also, the trace doesn't show it well, but the 4rth spark has a higher voltage peak than the 3rd and second spark, as the energy is declining and so the voltage has to rise further to compensate. Fred

Originally Posted by Neil Harvey

This turned ugly quick.

This forum is for car owners who wish to do a lot of their own work, come on here for advice and knowledge. If we as pros wish to contribute, we should do so in the spirit of this forum.

Who cares what the scope traces look like, or how the ignition 'works". Really?

I'm a user of ignition just the same as the end user. I want something that is reliable and won't leave the owner stranded on the side of the road. If it gives some added benefits more the better.

I can understand the theory, but that should be for another forum. Where all "pointed headed geeks" can have their say. Here I believe if we wish to repair, sell or supply any part to the DIY community, it should be kept with the spirit of the forum and information given and not challenged in the open. We should be informative and as companies identify what the DIY owner actually needs in an ignition system. Is it because they want more power or is it because they want a unit that is reliable. I'll bet every penny for a dollar its the later.

Who cares if CDI is better than Inductive when it deteriorates down to the level this has gone. I can tell you we prefer CDI in the Porsche 911 engine with the hemi chamber. That does not mean that Inductive will not run the car. Our testing results are private and we do not throw them around in an effort to sell anything. When it comes down to "show me your dyno results or you are lying" the whole point of helping the DIY is lost. Get real, its not about dyno results but credibility, both product and company.

We test all products we sell and they all have to meet our quality standard. Both the units we sell do this in excess and both have their own advantages.

I have never had one customer call and ask, does your CDI unit make more power than this one? Show me your Dyno results? Everyone asks, is it reliable and will it leave me stranded. That you can take to the bank!!!!

This argument over CDI verse Inductive is never going to end. As a engine engineer (with a little experience) I can tell you both have their place. We use both. But one is better suited to certain applications in our opinion. That's it.