Viable TWIN PLUG solution???

[WydRyd]

Guys, in my quest for a cheap'ish aftermarket high-output ignition system for a twin plug conversion, I've come across this MSD DIS-2 Ignition Unit.

I believe this unit can fire two coils at the same time. I don't want to run TWO MSD 6AL's, nor do I want to drive two coils off the one MSD 6AL

The DIS-2 unit is typically used in a wasted spark setup, but I assume it can be used to fire two MSD coils to a 964/993 twin distributor.

Can some of you ignition guru's please advise if this would work?

I want to run a high output ignition system so I can open up my plugs to 0.040" for better cleaner combustion at high boost levels (~1.3bar).

Thanks in advance

[mb911]

Merv just out of curiousity why have you chossen the 964/993 dizzy?? I have been told they do not have the same curve as what is required for your 3.3?? Is that correct?? Anyhow Just about to embark on the same thing only with MS as the driver

[WydRyd]

Ben, my motor is actually a Carrera engine with 930 P&C's. The 964/993 dizzy is a direct drop in replacement for the single Carrera dizzy. Simple twin plug solution really. Well, kind of... I'm still trying to figure out the best way to fire the twin dizzy without having to buy two Crane or MSD boxes

I just came across this AEM Twin Fire Ignition Module too, which looks promising and has a higher output voltage than the MSD/Crane:

http://www.aempower.com/ViewCategory.aspx?CategoryID=78

What do you guys think?

I looked at the Andial splitter solution and the other solution using the 993 ignition module, but it won't be powerful enough for ~1.3 bar of boost. I must have a more powerful CDI solution.

[iamchappy]

I use a single MSD 6 BTM to fire both coils and handle my ignition retard.

The coil leads from the MSD are pigtailed and wired to the separate coils. I am using a twin plug Distributor conversion from Supertec.

The coils deliver the juice.

I know many disagree with this setup but it was what (Henry) Supertec advised me to do, and it's something they say works fine.

[mb911]

Originally posted by iamchappy
I use a single MSD 6 BTM to fire both coils and handle my ignition retard.

The coil leads from the MSD are pigtailed and wired to the separate coils. I am using a twin plug Distributor conversion from Supertec.

The coils deliver the juice.

I know many disagree with this setup but it was what (Henry) Supertec advised me to do, and it's something they say works fine.

I was under the same impression and also believe that the 993 dizzy setup is not curved correctly nor could it be but again I could have misunderstood my souces

[iamchappy]

With my engine I am not looking to extract every possible bit of horsepower out of it. I realize that there are more sophisticated ways than my setup and theories on volts, ohms and resistance drops firing two coils with one MSD. I dont think I could notice the difference but I am sure there are instruments that measure the difference. If i was using my car to competitively race all those things would come into play, but my 914 is a street car, my engine set up with the one MSD should deliver plenty of spark for my enjoyment.

I am also using only one fuel pump, a Bosch 044 which may also be under achieving but should deliver enough fuel for my short bursts around town.

[Lorenfb]

"looked at the Andial splitter solution and the other solution using the 993 ignition module, but it won't be powerful enough for ~1.3 bar of boost. I must have a more powerful CDI solution."

Like what're the magic numbers and what does a "more powerful CDI" mean?
Or is this more of "I read it on the internet" kinda of info and "the way" to do it?

[WydRyd]

iamchappy, looks great! How much boost is your engine running? Have you noticed any ignition breakdown in the top end?

I might just bite the bullet and try running an extra LX-92 coil in parallel with the first coil and see if it works OK.

The RX7 guys run a single HI-6 and two LX-92 coils in parallel with their big power rotaries running 25-30psi boost and they seem to be holding up OK. Should be fine on my car running a conservative 1.1bar on a daily basis

[iamchappy]

Not running yet, soon, the body is still waiting for the top coat. I plan on working it up to 1 bar. I have the euro fuel head and a 7th injector if I need it to keep the AFR's safe. If my engine puts out 400hp + in my 2200 lb car I think I will be satisfied. Henry told me the single unit firing both coils works fine, so I am going to believe that it works fine. I dont know about drop out as I havent gotten there yet.

My engines not the state of the art engineering like yours but it is the best build I could do on my budget.
Started as a 79 SC 3.0:
930 ported intake and runners with Euro fuel Distributor
Supertec Gen2 twinplug conversion distributor
91 3.3 pistons and cylinders using the SC rods with offset bushing modification
Supertec Head studs
Arp rod bolts
racing valve springs
turbo oil pump
K27
1080 CFM intercooler
MSD 6 BTM with 2 Blaster coils
Tial bov and wastegate

Thats about it... it should work fine for me and my little car

I will finish the plumbing for the intake and charge when I get it back in the car.

[WydRyd]

Originally posted by Lorenfb
"looked at the Andial splitter solution and the other solution using the 993 ignition module, but it won't be powerful enough for ~1.3 bar of boost. I must have a more powerful CDI solution."

Like what're the magic numbers and what does a "more powerful CDI" mean?
Or is this more of "I read it on the internet" kinda of info and "the way" to do it?

Lorenfb, the OEM coils off an Andial splitter won't be powerful enough for a motor running 1.3-1.4bar of boost. That's what I'm told by a reputable turbo tuner. The boost blows out the flame and you get ignition breakdown in the upper end. That's why I need a more powerful ignition system.

iamchappy, at 1.0 bar I think you'll be fine. My main concern was what happens when boost pressures reach 1.3-1.4bar Will the energy output be strong enough with the two coils in parallel? I guess the only way to answer that is to try it and that's what I'll do. Run two LX92 coils in parallel. Fingers crossed.

[Lorenfb]

"That's why I need a more powerful ignition system."

More powerful = What?????????

"the OEM coils off an Andial splitter won't be powerful enough for a motor running 1.3-1.4bar of boost."

Based on what technical FACT?

"That's what I'm told by a reputable turbo tuner."

Right, another self-proclaimed one, like so many!

Here's a good example, NOT:

"Henry told me the single unit firing both coils works fine"

"I might just bite the bullet and try running an extra LX-92 coil in parallel with the first coil and see if it works OK."

Then guess again!

[IROC]

Loren, do you have anything to add to the thread or are you simply going to tell everyone else they're wrong?

Mike

[iamchappy]

I think Henry Schmidt at Supertec has experience regarding this.
It is also safe in regards to CDI failure, if one dies in a twin CDI setup you wont know it till its too late. On a single CDI if it fails you will know it immediately.

[WydRyd]

Originally posted by Lorenfb
"That's why I need a more powerful ignition system."

More powerful = What?????????

"the OEM coils off an Andial splitter won't be powerful enough for a motor running 1.3-1.4bar of boost."

Based on what technical FACT?

"That's what I'm told by a reputable turbo tuner."

Right, another self-proclaimed one, like so many!

Here's a good example, NOT:

"Henry told me the single unit firing both coils works fine"

"I might just bite the bullet and try running an extra LX-92 coil in parallel with the first coil and see if it works OK."

Then guess again!

Geez Lorenfb, please provide constructive feedback!

- More powerful = more powerful spark = greater plug gap = cleaner more efficient burning of fuel. I'm not stupid!

- OEM ignition/coils WILL NOT handle over 1.2bar of boost. How do I know? Because I've tried it and I get ignition breakdown in the upper RPM range. Once I fit a Crane CDI box in, the ignition breakdown is no more! Technical FACT!

- Yes, Todd Knighton of Protomotive is a highly reputable turbo tuner for both OEM and aftermarket stuff. He didn't win the European 996TT Shoutout based on pure luck/fluke or guessing!
Read here.

- Many people have used a single MSD 6AL and firing two Blaster coils in Parallel. The thing is, I already have a Crane HI-6 and my research has shown in practise, the HI-6 WILL AND CAN fire two LX92 coils in parallel. I contacted a Mazda RX7 tuning shop and they are running this exact configuration on a 13B rotary motor running 22psi of boost and making 600RWHP using a Crane HI-6 firing two LX92 coils in parallel. REAL LIFE example!

[911boost]

Merv,

I have a crank fire set up. I can get you some details if you want.

Bill

[WydRyd]

Thanks Bill. Any constructive info would be welcome here.

[Lorenfb]

"More powerful = more powerful spark = greater plug gap = cleaner more efficient burning of fuel"

Most forget that there are many elements to a spark:
1. peak spark voltage (not the same as energy) - measured in kilovolts
2. spark energy - measured in millijoules
3. spark duration (burn time) - measured in microseconds
4. spark rise time - measured in nanoseconds

"Many people have used a single MSD 6AL and firing two Blaster coils in Parallel."

I. Not reliable CDI operation
1. Causes excessive SCR & capacitor currents
2. Bad coil affects (kills) both spark plugs

II. Doesn't provide adequate spark energy & voltage:
1. Spark energy divided between coils
2. Spark duration reduced (burn time), burn time is very short for CDI vs Inductiive Discharge Ignition
to begin with
3. Spark peak voltage reduced
4. Spark plug impedence (carbon) affects both sparks
5. Spark rise time increased

Bottom line: The above and other factors are why few if any OEMs run a CDI
system, e.g. Mercedes Benz uses a Inductive Discharge System (2 coils in
one assembly driven by two separate drivers) for their twin plug ignition.
Using a "waste" type coil (dual output) on the same cylinder, provides
an inadequate spark especially in a turbo application.

[89turbocabmike]

Merv, I looked closely at the AEM 8 channel system for my twin plug and after much research and speaking directly with an AEM engineer at the SEMA show decided to pass. Although a great price point, they have had so many problems with the units that AEM pulled them from the market for a redesign.
I would look at the M & W Pro-16 CDI unit with their double ended coils. Not cheap, but neither is an engine rebuild as you know. I've come to the conclusion that it just doesn't make sense to skimp on such a critical component on our cars. $1600, will get you an solid ignition that will eliminate one tuning unknown.

[mb911]

Originally posted by Lorenfb
"More powerful = more powerful spark = greater plug gap = cleaner more efficient burning of fuel"

Most forget that there are many elements to a spark:
1. peak spark voltage (not the same as energy) - measured kilovolts
2. spark energy - measured in millijoules
3. spark duration (burn time) - measured in microseconds
4. spark rise time - measured in nanoseconds

"Many people have used a single MSD 6AL and firing two Blaster coils in Parallel."

I. Not reliable CDI operation
1. Causes excessive SCR & capacitor currents
2. Bad coil affects (kills) both spark plugs

II. Doesn't provide adequate spark energy & voltage:
1. Spark energy divided between coils
2. Spark duration reduced (burn time), burn time is very short for CDI vs Inductiive Discharge Ignition
to begin with
3. Spark peak voltage reduced
4. Spark plug impedence (carbon) affects both sparks
5. Spark rise time reduced

Bottom line: The above and other factors are why few if any OEMs run a CDI
system, e.g. Mercedes Benz uses a Inductive Discharge System (2 coils in
one assembly driven by two separate drivers) for their twin plug ignition.

very good info what set uo would you suggest?? I am considering EDIS or something similar for my set up.. I though am using megasquirt

[Lukesportsman]

Loren:
No one doubts your knowledge or conviction to the great Pcar electronics, BUT can you offer Merv some ideas. You've clarified your issues with the split CDI box to coil. I personally don't like the idea completely either.

I'd like to see a hotter box than a MSD 6a or BTM on a 1.4 bar engine, but I race big blocks with 14.5:1 spinning 8000rpm so I'm ignition hungry.

What do you suggest as options for Merv or others in this application? Finding weakness in ones argument is the first part of a debate (which again I don't doubt your ability) but then to finish you should give your ideas. Please just don't tell us what won't work in your opinion, but tell us what might in your opinion.