Some of us that work in this business are so busy every day we don't really know the difference between our ass and our elbow. I am one of them. I often get it wrong. Take a look at my failure pile of crap that never worked. If I could take back all of the money I have wasted trying something, I'd be a millionaire twice over.

I knew the input into each coil would be the same just got the circuitry wrong, based on test we did years ago. In defense of Henry, I have tried and tested driving two coils with one of the CDI units we sell. It made no appreciable difference on the engine we tried. Too many other factors at work here. When you have engines that produce small torque numbers, finding differences becomes very difficult. I'm sure the MDS would be the same but I have not tried MSD as we do not sell MSD. Henry does so maybe he has.

This test was the basis of using one CDI with dual internal channels driving two coils at the same time.

When you work in this business you quickly understand there are many different levels of customer needs. There is the "hot rod" customer who wants the best or there is the customer who needs just a little more than stock. Henry, suggested something that was for the customer who needed just a little more than stock. In this business we see all of them. You quickly know and understand your customer. Henry did just that by offering a simple solution to a customer who appeared to need a little more than stock. Maybe Henry read the customer wrong too, but that was not for the rest of us to find fault.

You also see those that want to find fault all of the time by admitting to age old differences. Who cares!! Add value and advice even if its wrong. Its not about who is right as we all can learn something. I learn something every day. I may not agree with everything Henry suggests as he may not agree with what I suggest. But that does not give me the right to attack.

Keep it up Henry. I value what you say. Even if I think otherwise, it makes me think about what you suggest and gives my brain a chance to start up every day.

I come to the engine rebuild forum often but rarely post. It seems like a place where a community of like-minded people come to share ideas based on experience.
Now, I read the shyt Wniders post and I wonder what pathology lies beneath the noise.
Egotism is obvious, the desperate need to be “right” above all else. A self-appointed arbiter of right and wrong. We also see an insecurity based on a persecution scenario about a 13-year-old post. The sad part is the envy. We see a troll question the offerings of genuine experts with decades of experience in ways that suggest his mommy didn’t hug him enough.
Henry comes here for 20 years offering free advice based on 40 years of Porsche experience and you come here with nothing but pompous arrogance, childlike insecurities and the obvious need to be better than. The community doesn’t need your brand of noise.


Full disclosure: Supertec has been building my Porsche engines for over 25 years.

....somehow after 30+ years as an executive I am not looking for guidance on how to tell **** from shinola, but merely have seen over time that Henry is usually at a minimum a totally valid point of view and usually better than that.

I have learned to go with the player with the better track record...so that's where it will be.

...and yes, I do not agree with Henry's point of view on 993 studs and have them in my 3.4 build.

D.

Back to the original post question maybe the reason was the store didn’t have enough of the same plugs in stock

As the conversation about single CD triggering a twin plug system, here is some factual data.
I built this little car in 2011. It is a 9.5:1, 2.45 liter (70.4x 86mm), 40mm Weber mod "S" twin plug engine running on one MSD CD. This engine dynoed at 180 rear wheel horse power @ 6300 rpm. Pretty good numbers given the spec.
I sold this little car in 2011 and it recently returned to a mechanic friend of mine.
The car had a clutch issue after 21,000 miles. When the engine was out , the plugs were removed and a complete service was planned.
The engine was still running strong. The plugs were functioning properly and the cap and rotor showed no issues. Anyone running twin MSD CDs will confirm that plugs, cap and rotor would all be needing replacement. Extremely high energy systems burn up components. Back in the early days when we first started using MSD CDs to replace factory Bosch CDs we had to order special rotors because the resister in the Bosch rotors would burn out within a few hundred miles.

http://forums.pelicanparts.com/uploa...1704911491.JPG
http://forums.pelicanparts.com/uploa...1704911491.JPG
http://forums.pelicanparts.com/uploa...1704911491.jpg
http://forums.pelicanparts.com/uploa...1704911491.jpg

You cannot argue real world results.

If I was one of those Spark plugs I may be pissed to be laid upon someone's old jockey shorts?

Are those Y fronts in the photo?

Anyone using these MSD Ultra 6A boxes? I bought a pair to replace the larger Crane units that I was using. The new ones will be taking up a lot less space. Probably gonna mount them stacked in the stock coil location and put the coils on the fan housing.

http://forums.pelicanparts.com/uploa...1705006482.jpg

My friend sent me the picture (at my request) and I didn't notice the lingerie. I guess that's what makes you so good at what you do.

What should the gap be on those? Or just use them right out of the box?

Oh my..

I must chime in.

First of all, I don't have 40 years of experience in building Porsche aircooled engines. I still haven't rebuilt a flat-6 and from the prices I find for parts and machine work I hope I never do.

Guys like Henry I have a special reverence for. Harry Pellow was another one. In the engineering world, guys like Henry and Harry are called "greybeards" They are the guys you go to first.

I think we need to go back to basics for this thread. The energy of these ignition systems is stored in the coil and not in the MSD box. 12 volts goes into the coil and by PFM (pure Fxxxxxx magic) 30k+ volts comes out. I don't know the output of the coils of the top of my head, just a lot. The coil in these cars works on the same principle as the transformer on the top of a telephone pole but in reverse; BIG # volts goes in and its stepped down to LITTLE # volts. I don't know the numbers on the pole so you guys will have to cut me some slack. If you only want to run your TV and washing machine, your house will have 110v in the wall. If you want to run a TIG and your welding aluminum and you have a electric dryer, you will want 220v.

I'm just a retired mechanical engineer. Good electrical engineers are wizards. We can probably lay all this at the feet of James Maxwell.

https://en.wikipedia.org/wiki/James_Clerk_Maxwell.

If I was building a race car I would want to have a box for each coil. Remember if you want to win a race, first you must finish and two independent ignition systems will be more reliable than a single box running a twin plug system.

If I was building a street car and one box was adequate then I would use one box. These cars are old so maybe i would bring along a spare box if I was doing a road trip.

If you have ever seen an airplane sitting on the end of a runway with the engine running for a time, the pilot is probably going thru a check list and one of the items is a MAG check, where he/she turns off one of the ignition systems and looks for a small drop in RPM. If one mag fails, the engine will still run and the plane will still fly, but not as well with both systems.

As far as the two different plugs, I would measure the resistance of both. I would expect them to need the same resistance. I also would check all the coil wires. If I found two different resistance values I would start investigating why.

ok, back to your local programming