Twin Spark Firing using single CDI Box

[winders]

You can guys can provide 20 examples of single MSD ignitions with 2 coils if you want. That doesn't change anything said previously in this thread.

Mark, I rcommend putting put a set of RSR spark plug wire retainers on those bottom plugs....

[Neil Harvey]

In a CDI Ignition system, the energy is created and stored in the CDI unit. The coils add not energy to speak of. So adding two coils will make no difference. But, you should expect the energy released at the plug tip to be less is the output of the CDI is shared at the same time. How much I do not know as I do not use MSD nor have I ever shared one CDI unit with two coils.

An engine is the sum of its parts and the Ignition system is one of these parts. In my opinion, it is one if not the most important part. You can have all the fancy parts included within your engine but if the Ignition is weak, your parts are not been used at their full potential. Ignition is the last function to happen before the mixture is ignited.

In any engine, performance expectations and the engine budget have to be in sync. If the budget does not allow for a high end Ignition system, then compromise has to be had. However, in my opinion, other costs should be considered first before compromising on the ignition system. This been said, I do understand that the cost of the lower end ignition systems have their place. You have to understand that failures can and do happen with any part and more often happen with parts made to a lessor quality.

To say that these lower quality system have been working for years and the car runs great, is somewhat short sighted is the other systems available have not been tried. Anything will feel great, but maybe another system would feel even better. An engine with contact points inside the distributor and a single coil, will run the engine. To some, just fine.

I have been using and selling for over 20 years a system made in Australia. Its made to a very high quality, a level we require in our engine builds.

But I will also give any CDI system its due credit over any Inductive system used on these early hemi-headed engines. The problem with 12 plugged engines is the complexity of any CDI system if a Distributor is not used. It requires 2 6 channel CDI units and 12 coils. Lots of wiring and lots of HT wires. In many cases an ECU is required.

Inductive Ignitions came about due to the long duration spark required for emissions. Cost also was a huge driver here. To fit multiple Igniters is vey in expensive in comparisons, and 12 COP units is the same. The wiring is a lot simpler too. Unfortunately the energy released is low and the engines performance will suffer in comparison. Add to this, you have limits on engine RPM and have to program coil recharge times to make sure the coils are fully charged. More coils does help here, but the energy is still a lot less.

The higher the energy released, the less engines are prone to knock as well. The higher in cylinder temperatures created by the higher energy levels, allows for a faster burn time and the end gases are ignited before they ignite themselves from pressure.

In more modern cylinder head chambers where the volumes are a lot less, Inductive Ignitions can be used with long durations but the ignition maps look completely different. All are typically water cooled as well.

Choose wisely and in many cases if the low end MSD or Inductive systems work just fine for your use, enjoy the engine. Its not always about how much money you spend.

[KNIGHTRACE]

Thinking about it, these testimonials about single MSD on two coils, one could conclude their pretty good boxes to serve double duty. I doubt a Bosch or premature will not hold up to that. Good to share on the forum.

[winders]

But they aren't serving double duty. They send out the same amount of power the same amount of times. The coils are splitting the power.

[Henry Schmidt]

via GIPHY

[KNIGHTRACE]

Winders.. You are correct.. Have to stop multitasking as much.

[winders]

Originally Posted by Henry Schmidt

via GIPHY

Only because you did not like what you were being told......

[Henry Schmidt]

Originally Posted by winders

Only because you did not like what you were being told......

You mean this?

Originally Posted by KNIGHTRACE

.....edit......I strongly suspect a low compression N/A motor at like 9.5:1 with low resistance plugs and no large gap would work very fine and give no issues.
......edit........
On these questions with mechanical injection I know enough to give you Henrys phone number as that is not my domain. I have done maybe 10 MFI motors in my life but I am far from an expert. I hope the Pelican community is grateful for people Like Henry and myself and others who take time out of their day to answer questions. . WK

[winders]

There you go confusing one thing with another again. But you go right ahead and keep missing the point.

[Henry Schmidt]

Originally Posted by KNIGHTRACE

...edit...The green feed wire from the star wheel often has the polarity reversed. The internal insulated wire should be the positive but often the outer braided wire is the positive. This has been the issue quite often, rather than fixing the distributor I have reversed the wires to get them correct on polarity more often than not.

As a general rule, the A wire is the shielded wire in the Porsche green wire (930 602 907 01) connector and if reversed the distributor will fire out of phase.
The problem with "general rules" is you have to know the exceptions.

I watched a very successful race team explode an engine because they were unaware that you reverse the wires you can destroy an engine. They knew the rule "coated internal wire is A" but they didn't know that their clockwise distributor was the exception.
What they didn't realize like most people, is that clockwise rotating Bosch distributors have reverse polarity. The clockwise distributors (euro 3.0 Carreras and 3.0 turbos)have the wires reversed. The factory identified the reversed polarity by making the connector blue as apposed to green. The blue wire was discontinued years ago so the only reasonable solution is to run the green wire and reverse the wires at the box.
You can (and we have) re-positioned the star wheel but that is an unnecessary exercise.

[KNIGHTRACE]

installing an MSD help tip's. #1 large red wire can attach at the large positive terminal on the starter do not use the existing feed wire for the previous as main power supply. #2 if you are not installing a new distributer and you know your ignition timing is correct your timing will be the same with the MSD. #3 check timing after installation of new MSD before you drive car if the timing on the ignition is the same as before your polarity on the magnetic signal is correct, if all of the sudden the timing reads about 60 degrees off "typically advanced"you have to reverse the magnetic signal from the distributer. The MSD will run with the polarity reversed but usually the ignition will shut down and stop working after some time driving the car in a mysterious fashion and restart after it cools often. #4 if installing a new Distributer rotate the motor to TDC #1 and point the rotor in the distributer at #1 spark plug in the distributer cap. Start the motor if the timing reads around + or - 10 degrees from TDC your magnetic signal polarity is correct, if the timing light says it is off by a large margin you have reversed polarity on the magnetic signal from the distributer. Many MSD units that get a bad reputation are often because of a reversed polarity on the magnetic signal. I added this to help do it yourself individuals make their install much easier.

[Henry Schmidt]

When we send out one of the twin plug distributors we build, we include a these simple instructions. They are applicable regardless of the ignition you choose.

[KNIGHTRACE]

Hum, again this is where we do not to clash technical minds because this is not a help to the pelican people. But I do not think the rotation of the firing order determines the polarity output from the distributer. The internal shielded wire in the green wire should always be the positive in the magnetic output. The a/c wave generated is the same either way you spin the distributer. It has been years since I built distributers but my reason for posting this is I do not want people to assume that if they have a counter clockwise distributer it means the polarity is reversed. I have used hundreds of counter clockwise factory distributers and sometimes there right and sometimes there not. This is not referring to Henrys distributers I am sure his products are good but I don't know much about them. This is about stock distributers and is to help Pelican people install their system and have it work properly.
To summarize what I am trying to say as the post I made above. Please use the simple few rules I posted above to check your polarity when installing a new ignition unit. I like Henry and I am not trying to have a competition on this or a heated debate, Both Henry and Myself will get it correct 100% of the time. My reason to push people to check it is you will also get it correct 100% of the time rather than looking at a diagram and assuming your equipment matches the diagram.

[BURN-BROS]

Back in the day Porsche made 2 wires for the Mag Pulse 911 distributor. The Clockwise rotating distributors like on the 3.0 Turbo had a Blue wire, while the CCW dizzy's had a Green. It was not only a difference in color...The wires were moved internally to correct polarity.

The effects of rotation on the Mag-Pulse is verifiable on a distributor machine.

[Henry Schmidt]

Originally Posted by KNIGHTRACE

Hum, again this is where we do not to clash technical minds because this is not a help to the pelican people. But I do not think the rotation of the firing order determines the polarity output from the distributer. The internal shielded wire in the green wire should always be the positive in the magnetic output. The a/c wave generated is the same either way you spin the distributer. It has been years since I built distributers but my reason for posting this is I do not want people to assume that if they have a counter clockwise distributer it means the polarity is reversed. I have used hundreds of counter clockwise factory distributers and sometimes there right and sometimes there not. This is not referring to Henrys distributers I am sure his products are good but I don't know much about them. This is about stock distributers and is to help Pelican people install their system and have it work properly.
To summarize what I am trying to say as the post I made above. Please use the simple few rules I posted above to check your polarity when installing a new ignition unit. I like Henry and I am not trying to have a competition on this or a heated debate, Both Henry and Myself will get it correct 100% of the time. My reason to push people to check it is you will also get it correct 100% of the time rather than looking at a diagram and assuming your equipment matches the diagram.

My distributors are based on production Bosch distributor is all cases. The reversed phasing/polarity is a fact.
On all Porsche pointless distributors delivered as standard equipment, clockwise distributors have a reverse polarity A vs B connector to the counterclockwise distributor. The AC wave may be the same but the relationship to the star wheel and the coil changes.
The fact that Porsche made a different connector wire (blue vs green) for early pointless distributors (clockwise rotating) is a pretty good indication that something is difference. Both plastic ends are the same. They both run a shielded wire.
So, electrical experts, please explain what might be different to us uninformed?

If memory serves me, Andial actually made an aftermarket connector wire when Bosch discontinued the blue wire.

If you really want to have some fun, check the polarity/phasing on a mid 80s BMW distributor. They have the same internals as the pointless 911 Porsche distributor. They rotate CW and are wired reverse to the CCW Bosch distributors in 78-89 930 and 78-83 911 SC.

[Henry Schmidt]

Originally Posted by BURN-BROS

Back in the day Porsche made 2 wires for the Mag Pulse 911 distributor. The Clockwise rotating distributors like on the 3.0 Turbo had a Blue wire, while the CCW dizzy's had a Green. It was not only a difference in color...The wires were moved internally to correct polarity.

The effects of rotation on the Mag-Pulse is verifiable on a distributor machine.

Good morning dude.

You guys should listen to Aaron. He knows more about these distributors than anyone I know.

[BURN-BROS]

Happy Tuesday Henry!

[Henry Schmidt]

Originally Posted by KNIGHTRACE

Best coil for MSD is black Blaster 2 high vibration in case someone is looking. The 6Al digital works well thankfully they make them black now, I never liked the red.

Here's a side note about humor.
My post about "just a few bucks more" is an important commentary on the snowball effect. It was not intended as a referendum on the virtues of any one system over another.
If we can't add a little humor to some of this tech shyt, life gets pretty boring.

Although you may be having gook luck with the digital 6AL our experience is different.
The analog 6 AL prior to the most recent digital boxes were far more reliable.
That is why we spend a little bit more and are now recommending the analog
6 ALN.

[KNIGHTRACE]

I am fine with the MSD 6AL that Henry likes, I did not know they made it any longer, Advantage of the digital for me was the ability to dial the rev limiter to whatever I want vs the plug in rev limiters on the 6Al. Both "soft Touch" rev limiters feels like someone hitting the back of your helmet with a baseball bat. When I used aftermarket ignition systems the best one I ever used was the Crane digital box that was blue 20 years ago but they were about $450 each back then. One thing I used MSD made that I do not think they make any longer was there timing computer. It ended grinding down weights and finding lighter springs and all of the madness compared to pulling the weights out of your distributer and mechanically advancing it to wherever you wanted your total timing. It also enabled you to pull degrees in the higher RPM that you could not do with a regular distributer. MSD now makes like a 6ALBT or something like that that is excellent for CIS turbo motors because you can pull timing from boost at what ever level you want and you do not need to rely on vacuum canisters on the distributer. I hope everyones efforts on this thread help out some people.

[LJ851]

Originally Posted by Henry Schmidt

My distributors are based on production Bosch distributor is all cases. The reversed phasing/polarity is a fact.
On all Porsche pointless distributors delivered as standard equipment, clockwise distributors have a reverse polarity A vs B connector to the counterclockwise distributor. The AC wave may be the same but the relationship to the star wheel and the coil changes.
The fact that Porsche made a different connector wire (blue vs green) for early pointless distributors (clockwise rotating) is a pretty good indication that something is difference. Both plastic ends are the same. They both run a shielded wire.
So, electrical experts, please explain what might be different to us uninformed?

If memory serves me, Andial actually made an aftermarket connector wire when Bosch discontinued the blue wire.

If you really want to have some fun, check the polarity/phasing on a mid 80s BMW distributor. They have the same internals as the pointless 911 Porsche distributor. They rotate CW and are wired reverse to the CCW Bosch distributors in 78-89 930 and 78-83 911 SC.

When I made my 3.2 distributor functional to work with my 46mm PMOs I used BMW, Mercedes and Porsche Bosch parts. It is surprising how similar all the Bosch distributors are from the 70s-80s. Hell, it has BMW 2002 advance weights in it.

I wired the analog MSD 6AL the "correct" way and the car would barely run and clearly was not happy. When I checked the rotor phase it was Way off and I thought I had made a mistake but reversing the polarity brought everything in line just like Henry is describing.




Winders, would you be OK if someone used a MSD ignition differently than you did on your engine?



I don't like the Red MSD case either but a can of PJ1 satin black case paint fixed that right up.







...