observations of new CDI Unit
03-10-2003, 01:18 AM
#16
Cruisin'
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John D,
I will try to answer your questions.
I have owned my car for many years. I am now on my 4th CD unit. I will list them in order of change.
Bosch #1. came with car when I purchased it.
Bosch # 2. Rebuilt unit approx 3 years ago. This unit was replaced with new distributor.
Failed in January 2003. Would not start car at all. Was replaced with another loaner and car started right up. The Permatune, brand new and lasted approx 1 month. This unit let me down 6 times and finally stranded me on the freeway. Every time the car would stop and after some time would start up again. The last time it would not start at all. Have you ever paid to have your car towed off the freeway. I could have almost paid for the engine to be rebuilt. Just a note about the towing. My AAA only pays for 7 miles. As for how well my car ran. I have it serviced by the same mechanic and often. The engine was rebuilt some time ago and at the present has around 18K miles on it. The timing and fuel mixture were checked for a recent smog test. When this new CDI unit was installed, my mechanic had to readjust the mixture. I asked him why and he told me he thought it was because of a hotter spark and better combustion. The car runs harder and pulls more RPM's. Starting is way better, cold mornings especially, and the engine sounds different. Not to mention I have seen better fuel economy. I'm puzzled why we have never heard of this CDI before. I'm just really happy I have one now.
Paul
I will try to answer your questions.
I have owned my car for many years. I am now on my 4th CD unit. I will list them in order of change.
Bosch #1. came with car when I purchased it.
Bosch # 2. Rebuilt unit approx 3 years ago. This unit was replaced with new distributor.
Failed in January 2003. Would not start car at all. Was replaced with another loaner and car started right up. The Permatune, brand new and lasted approx 1 month. This unit let me down 6 times and finally stranded me on the freeway. Every time the car would stop and after some time would start up again. The last time it would not start at all. Have you ever paid to have your car towed off the freeway. I could have almost paid for the engine to be rebuilt. Just a note about the towing. My AAA only pays for 7 miles. As for how well my car ran. I have it serviced by the same mechanic and often. The engine was rebuilt some time ago and at the present has around 18K miles on it. The timing and fuel mixture were checked for a recent smog test. When this new CDI unit was installed, my mechanic had to readjust the mixture. I asked him why and he told me he thought it was because of a hotter spark and better combustion. The car runs harder and pulls more RPM's. Starting is way better, cold mornings especially, and the engine sounds different. Not to mention I have seen better fuel economy. I'm puzzled why we have never heard of this CDI before. I'm just really happy I have one now.
Paul
03-17-2003, 12:46 PM
#18
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OK, got an email back from MW. I asked:
Now, my understanding of electronics is pretty basic, but wouldn't the impedence of those coils not be identical, so one of the two would see more current?
He replied: </font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Tom
Your theory is correct however in practice it works fine as the coils we supply or suggest are made to such high standards these days.
We have been firing two ignition coils wired in parallel for years as we often find it a better setup than using an ignition coil with dual secondary outlets as these present some interesting problems too.
We have been making 'quality' ignition systems for many years and the premier series of motor sport in Australia, V8 Supercars, now uses them exclusively. We use only the best of components and thoroughly test the unit before sending it out to the customer. You will note that there is now a photo on the front page of our web site showing the construction differences between our ignition and brand 'P'. I shook my head the first time I saw a 'P' as it is basically rats-nest construction which went out with valve radios!
The US is such a large place that it doesn't surprise me that few have heard of us. We are looking at doing a replacement ignition system in the near future that will look like the factory Bosch unit and will mount directly in its place, the only thing that will have to be changed will be the connector and due to the age and condition of the wiring in the cars I have seen this will be a bonus.</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I then replied asking which coils they reccommend, to which he answered:
</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">
For a cdi ignition you want the lowest inductance you can find otherwise you end up wasting energy as heat in the ignition coil. With our multi channel units we use a ferrite core ignition coil which has a peak primary current of 120A vs about 40A for a conventional iron cored ignition coil.
Bosch made a small metal can style ignition coil which was supplied on some versions of the 911 and this was optimised for their CDI ignition. It was quite short and heavy for its size. Unfortunatly I haven't had the opportunity to test one of these.
Bosch Australia make quite a good transformer style ignition coil which we sell they are available with both male and female hight tension outlets. The primary inductance is comparatively low and we have used them successfully in many dual coil applications.
I don't know what coils you have at your disposal in the US so I am unable to quote a part number you can go out and buy. The best person to speak to is our west coast representative Neil Harvey at Performance Developments who I suspect is the person you spoke to in the first place.
</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Opinions?
Tom
Now, my understanding of electronics is pretty basic, but wouldn't the impedence of those coils not be identical, so one of the two would see more current?
He replied: </font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Tom
Your theory is correct however in practice it works fine as the coils we supply or suggest are made to such high standards these days.
We have been firing two ignition coils wired in parallel for years as we often find it a better setup than using an ignition coil with dual secondary outlets as these present some interesting problems too.
We have been making 'quality' ignition systems for many years and the premier series of motor sport in Australia, V8 Supercars, now uses them exclusively. We use only the best of components and thoroughly test the unit before sending it out to the customer. You will note that there is now a photo on the front page of our web site showing the construction differences between our ignition and brand 'P'. I shook my head the first time I saw a 'P' as it is basically rats-nest construction which went out with valve radios!
The US is such a large place that it doesn't surprise me that few have heard of us. We are looking at doing a replacement ignition system in the near future that will look like the factory Bosch unit and will mount directly in its place, the only thing that will have to be changed will be the connector and due to the age and condition of the wiring in the cars I have seen this will be a bonus.</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">I then replied asking which coils they reccommend, to which he answered:
</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">
For a cdi ignition you want the lowest inductance you can find otherwise you end up wasting energy as heat in the ignition coil. With our multi channel units we use a ferrite core ignition coil which has a peak primary current of 120A vs about 40A for a conventional iron cored ignition coil.
Bosch made a small metal can style ignition coil which was supplied on some versions of the 911 and this was optimised for their CDI ignition. It was quite short and heavy for its size. Unfortunatly I haven't had the opportunity to test one of these.
Bosch Australia make quite a good transformer style ignition coil which we sell they are available with both male and female hight tension outlets. The primary inductance is comparatively low and we have used them successfully in many dual coil applications.
I don't know what coils you have at your disposal in the US so I am unable to quote a part number you can go out and buy. The best person to speak to is our west coast representative Neil Harvey at Performance Developments who I suspect is the person you spoke to in the first place.
</font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Opinions?
Tom
03-17-2003, 03:43 PM
#19
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Tom,
I think I started another thread as UK Newbie question, about this very same Ignition system. I asked similar questions and received some information which gave me reason to order one this morning. As I posted on the other thread, I will post my experiences.
Nigel
I think I started another thread as UK Newbie question, about this very same Ignition system. I asked similar questions and received some information which gave me reason to order one this morning. As I posted on the other thread, I will post my experiences.
Nigel
05-20-2003, 01:32 PM
#20
The key parameters for an automotive ignition system are;
a min. spark energy of 60 milli-joules, a min. voltage of
30KV, and a min. rise time of 100 - 200 nanoseconds.
The stock Bosch Porsche CD unit provides these parameters
with great reliability (the most key parameter). Most
after-market designs achieve little beyond the original
factory units and have less reliability.
There's nothing magical about designing a system to meet
those parameters. Porsche used its CD design to win many
races without any problems. If there were a better design,
who would have more resources to achieve an ideal design,
Porsche/Bosch or a small after-market company. At the
time in the '70s, a CD ignition provided benefits.
Why has Porsche and all auto makers stopped using the
CD design and now use an inductive discharge system?
It's because they can now achieve adequate spark
parameters with the inductive discharge system at a
lower cost with better reliability than with a CD system.
You should always not discard the original Bosch unit.
You may have to go back to it in the future. Remember,
as you drive during a hot summer day about performance
claims versus reliability.
Check out this website (systemsc.com). It may provide
some additional insights.
Good luck
Lorenfb@aol.com
a min. spark energy of 60 milli-joules, a min. voltage of
30KV, and a min. rise time of 100 - 200 nanoseconds.
The stock Bosch Porsche CD unit provides these parameters
with great reliability (the most key parameter). Most
after-market designs achieve little beyond the original
factory units and have less reliability.
There's nothing magical about designing a system to meet
those parameters. Porsche used its CD design to win many
races without any problems. If there were a better design,
who would have more resources to achieve an ideal design,
Porsche/Bosch or a small after-market company. At the
time in the '70s, a CD ignition provided benefits.
Why has Porsche and all auto makers stopped using the
CD design and now use an inductive discharge system?
It's because they can now achieve adequate spark
parameters with the inductive discharge system at a
lower cost with better reliability than with a CD system.
You should always not discard the original Bosch unit.
You may have to go back to it in the future. Remember,
as you drive during a hot summer day about performance
claims versus reliability.
Check out this website (systemsc.com). It may provide
some additional insights.
Good luck
Lorenfb@aol.com
