You now have ME quite throughly confused....

A single MSD "box"/system driving 2 ignition coils.....

Unless that one MSD box had 2 "discharge" capacitor outputs then engineering wise this would be....

SHEER IDIOCY.

In series...? just not possible...

In parallel.....the first plug to fire would oftentimes, likely randomly, negate the firing of the second/other plug.

No one, NO ONE, should be surprised at your test result.

1 Ignition Box For 2 Coils? - MSD Tech Support Forums

From am MSD Support person:

"....if you wire the coils in series you can use an MSD Box, PN 6200, or PN 6420, or PN 6520. To wire the coils in series all you have to do is run the orange wire from the MSD Box to the (+) positive side or coil #1. Next run a jumper wire from the (-) negative side of coil #1 to the (+) positive side of coil #2. Then run the Black wire from the MSD Box to the (-) negative side of coil #2."

http://www.msdignition.com/forum/showthread.php?t=8064

From an MSD Support person:

"You can drive two coils using one MSD ignition box by wiring them in a parallel fashion; coil pos to coil pos. and coil negs. to coil neg. Realize that the power output from each coil, since you are dividing the energy between the two coils will be about half of what is normal for the ignition or the coil."

Scott

From post #69:

"1. The total current from the CDI splits but not necessarily equally between the two
coils which depends upon how well matched each coil is. The voltage, though, is the
same across each coil, but the energy transfer is basically half of the initial, again
assuming matched coils. This assumes the coils are in parallel. If in series then
the voltage divides between the coils and mostly likely unequally, and this being
the worst hookup.

2. Again, there is no correlation between voltage (in this case) and power (HP) since
the voltage is the SAME for coils assuming a parallel setup. In any case, connecting
two coils to one CDI is a Mickey Mouse setup whether series or parallel."

"A single MSD "box"/system driving 2 ignition coils.....

Unless that one MSD box had 2 "discharge" capacitor outputs then engineering wise this would be....

SHEER IDIOCY."

Totally correct!!!!!!!!!!!!

And the responses from the MSD support staff reflects their lack of any technical credibility.

intersting - why then bother with a dual plug conversion if the oem single plug bosch CD is perfect?

.

I didn't say using two coils on a single MSD ignition box was a good idea from a perfromance perspective. Just that it can be done based on information from the manufacturer.

Scott

I have to give Loren his "due" on this one, the MSD engineers who proposed driving 2 coils with one MSD undoubtedly had their head where the sun NEVER shines.

In series you would be doubling the inductance reactance, impedance, flattening the rise time even more. Plus you would need a 600 volt capacitor charge to equal the Bosch CDI.

In parallel the first plug to fire would "reflect" a short to the, its, coil primary thereby reducing both coils primary voltage significantly, making it unlikely that the second plug would ever fire.

'In parallel the first plug to fire would "reflect" a short to the, its, coil primary thereby reducing both coils primary voltage significantly, making it unlikely that the second plug would ever fire."

That's correct!

"intersting - why then bother with a dual plug conversion if the oem single plug bosch CD is perfect?"

Read the numerous posts by different posters as to the benefit of dual plugs on
the pre-996 engine.

I reckon if they could put the stuff from the red box thingy into an old empty grey box thingy they could fleece quit a few of the car cleaning show guys.

Kenwood Direct-Drive, Marble Base, Infinity Black Widow Carbon Tone Arm!

My Vote for Cassette - Yamaha TC-1000, I've got 2 that came out of Criterion Studios ( Allman Bros, etc). They tried to buy them back after the crap that they replaced them with took a dump.

You can, in fact, buy a Permatune in an old Bosch case. Which is rather like buying a Faberge egg full of styrofoam peanuts.

ATTENTION!

All of you who have a single MSD driving two coils on a twin plug engine are total idiots. Know how I know? Because Loren said so and he is backed up by wwest and others. So Henry, Steve and Mike I have lost all respect for your 30+ years of engine building and tuning you each have. You guys don't know s@#t about what you're talking about.

I am an idiot too; my POS 911 3.0 with twin plug distributor fired by one MSD box is a total turd. Oh by the way, any of you ignition experts want to run your 3.0 for pinks? Better think before answering.

http://forums.pelicanparts.com/uploa...1336744382.jpg

Always carry a spare Faberge egg.

************************************************** *******

Nice, very nice.

I'll go you one better.....!!

Let's widen your plug gap by double to simulate the plug fouling that likely results from carburetion, then we'll dyno your configuration, including simultaneous emissions analysis.

Then I'll foot the bill for installing a second MSD.

If the second run with an MSD driving each individual plug doesn't show at least a 10% improvement, 15% if your configuration is "parallel, average for both measures you get to keep the MSD/Installation. If not then you re-emburse me for all involved expenses.

Since my opinion of anyone that choses to deal with carburetion in this day and age is so low we don't need to discuss the idiocy factor. That aspect needs to be classed as a hobby, not, NEVER, performance tuning.

A. I've never had a plug foul even with only one MSD box.
B. I have said repeatedly that two boxes make more energy to each plug than one therefore more engine power.
C. My earlier post with the results from JB Racing already proves more power from two boxes.
D. You footing the bill for an MSD box isn't quite the same as your pink slip...

Lindy, what kind of #'s you making? That looks really nice!

"Since my opinion of anyone that choses to deal with carburetion in this day and age is so low we don't need to discuss the idiocy factor. That aspect needs to be classed as a hobby, not, NEVER, performance tuning."[/QUOTE]

Wow, I'll just sit back and wait for others to comment on this one.

Along this quote, I wonder if Lindy's second really does not fire? After all, how would one know (without testing) since one plug will get the job done and the cylinder will fire just fine. It wouldn't be like a total misfire and have instant feedback like aviation where you can easily ground the magneto out to test RPM changes.

Not trying to slam or pick sides, it's a valid question and could explain the hp difference between one box and two the more I think about it.

<<shrug shoulders>>

260 hp at the crank with muffler and air filters. 270+ with megaphones and open intake, 2150# car.

I have a 10.5:1 CR on pump gas. It would have blown up a long time ago if both plugs weren't firing. I have checked it though when it first went together with a pair of timing lights set up on both #1 plug wires. Both top and bottom wires fire the lights simultaneously.

One plug will only get the job done for a very short period of time before detonation ruins the day.

This is the primary reason for using one MSD rather than two. In the event one box fails of a pair, you would not know because the second box would still fire one plug resulting in catastrophic engine damage. With one box, if it fails, the engine ceases to run.

I see. Curious then how this can be explained away if MSD will fire 2 coils but theory says it won't?

Nice hp/weight #'s BTW.