Twin Spark Firing using single CDI Box

[Neil Harvey]

I am happy to extend my knowledge and experience for free to whom ever is interested. I understand that not everyone will agree nor will they accept what I have to say. But that is life and I don't get upset in any way over this stuff.

Way too many years in this business and one of the very lucky ones to work at the highest level of motorsport for many years. A humbling situation for sure. You get there often by luck but survive by your work and results.

I always liken it to college athletes. There are thousands of them but only a few get to play pro sports. If I can offer my knowledge of engines and their sub assy's I will.

How I go about building engines is all based on engineering. Engineering is firmly based on facts, figures and proven results. The good thing about Ignition, like the rest of the engine, it can be calculated with proven theories. There are well known equations for calculating the energy levels for both CDI and Inductive Ignitions. But you have to apply them to each engine and its differences. Hemi cylinder chambers behave totally different to small pent roof chambers.

Often these are dismissed in favor for what is more desirable, for a multiple of reasons. To each his own.

In our Pro Mod work we learned that you need all the power you can get from the mag. These put out around 44A and by rule we can only have only one. The cylinder pressures involved are enormous. But the same applies to engines with a lot less cylinder pressure. The spark plug starts the burn just around the small circumference of the plug tip. The energy released by the Ignition into the chamber turns from electrical energy into chemical energy and thus creates tremendous heat. Its this heat that burns the rest of the mixture. But as its been stated here, this got off topic some.

This forum should be for expressing ideas, knowledge and experience. Not everyone will agree. But all to often it turns nasty and those who really need to gain knowledge get turned off.

Sad.

[winders]

Originally Posted by Henry Schmidt

Most Porsche enthusiasts couldn't care less about grinding away in a meaningless club event.

Meaningless club event? PCA Cub Racing events are meaningless? To whom? To all the ladies and gentlemen racing putting their lives on the line to have a fantastic time pushing themselves and their cars harder and harder? To the people developing the cars, engines and chassis, so they can go faster than before? To the people developing themselves to become the best drivers than can be?

There are a lot of Porsche enthusiasts at these "meaningless club events". In fact, they are some of the most dedicated Porsche enthusiasts I have met. Most of the Porsche enthusiasts I have met would love to be able to participate in these "meaningless club events". These "meaningless club events" are what have continued the development of air-cooled 911s to the point you probably have a hard time conceiving.

The PCA Club Racing events are certainly not "meaningless"!

[winders]

Not meaningless to me or William Knight:

[Rosco_NZ]

Dear sweet Jesus, how did we end up here.

[manbridge 74]

Ask about head studs if ye dare!

[Jeff Alton]

Scott runs 2 ignitors being triggered by a Motec ECU firing 12 coils. The same way we fire twin plug COP motors, the same way Porsche started doing it with the 964 (but only with 2 coils). Not at all apples to apples comparison but the correct way to do it in his application. A single ignitor will not work in that set up.

[winders]

No. I have 4 ignitors (2 on each side - you only see the driver side ignitors in the photo) with 3 channels each so each coil gets its own ignitor channel.

I could have used a single 3 channel igniter per side but that would mean splitting the energy per coil in half. Each channel on the igniter is capable of 40kV and 12.5 amps continuous and 30 amps burst. The MSD red coil most people use puts 45kV and 140mA. So the WeaponX inductive setup has effectively the same voltage as the MSD CDI but with MUCH longer duration.

[LJ851]

Winders, what are the trays/panels under the air filters for? Do those seal to the decklid for cooler air?

Thats an impressive engine you and William have created. How do the COP compare to CDI in spark energy?

[winders]

Thanks! William designed it....I just asked a zillion questions!

The tray panels are for an air box setup that forces the ITBs to get their air from the openings in the deck lid. It works really quite well.

I put the CDI vs WeaponX inductive CoP setup in my previous post.

[LJ851]

Originally Posted by winders

Thanks! William designed it....I just asked a zillion questions!

The tray panels are for an air box setup that forces the ITBs to get their air from the openings in the deck lid. It wrk really quite well.

I put the CDI vs WeaponX inductive CoP setup in my previous post.

Thanks, I see the edit now.

[Henry Schmidt]

Originally Posted by Rosco_NZ

Dear sweet Jesus, how did we end up here.

What happened to this thread is "performance myopia".
The inability to see the value in performance enhancements that do not directly relate to race track performance.

We see this type of myopia when the show car people talk about DYI restorations. "What? that's not the original color? I wouldn't own that car."

Or among dog show people..."What bread is that? Funny, your dogs ears aren't the right shape."

And even among the Teddy Bear collectors: "The articulation in your bear's right leg is 4 degrees off."

A few year ago I had a very nice collection of old Colts, some of which were duplicates. I decided to take some of the more worn duplicates (1890, 1905) and send them back to Colt for restoration. The gun forums dweebs exploded.
One guy proclaimed with passion "the patina had history!"

Most Porsche enthusiasts are not racers. Most couldn't care less about PCA, POC or even IMSA racing. They want to enjoy the spirited ride offered by a well tuned Porsche. Maybe carve through a mountain road at six in the morning before the local LEO sets up his speed trap. They work with what they have, trying to stay within their budget. They upgrade their shocks (but not often JRZ with coil over), they buy performance tires but they generally want tread, they upgrade their exhaust but still want to hear their stereo and they want a little more compression but still run street gas..
To belittle those enthusiasts because "that's not how they do it at the track" cheapens the Porsche experience for far too many enthusiasts.

[LJ851]

Originally Posted by Henry Schmidt

As you can see "it's only a few bucks more" along with "while you're in there" are terms that need serious consideration every step of the way.
Cheers

*humor*

Says the guy selling a rebuilt distributor for $2200.00

*humor*

[Henry Schmidt]

I know what you mean.....way too cheap.

[mikedsilva]

Originally Posted by Henry Schmidt

And even among the Teddy Bear collectors: "The articulation in your bear's right leg is 4 degrees off."

This made me smile!

[winders]

Actually Henry, you have it wrong.

Porsche has spent their history proving and advancing their products on the race track. Racing is a huge part of what Porsche is as a company.

Twin plug setups from Porsche come from pushing the limits for racing. They didn't use twin plugs per cylinder because it was cool or looked trick. It was all about extracting the maximum performance they could from their engines. All of Porsche's air-cooled engines that used twin plugs per cylinder, both race and street, used an ignition module per coil. They never split the ignition power between two plugs firing at the same time. I know why they did this on the race engines. I wonder why they did this on the street engines when they could have saved money using a single ignition? Because it makes sense and is the right thing to do.

I don't know what show cars, dog breeds, Teddy Bears, or guns have to do with this. Actually, I do: NOTHING!

I agree that most Porsche enthusiasts are not racers. They might not even care about any car clubs or racing in general. But Porsche enthusiasts appreciate the racing roots of Porsche and the performance the name "Porsche" guarantees. If you don't know that by now, you surely don't understand Porsche or lovers of the marque.

I have been a Porsche fan since I was a little kid. My Dad took me to Riverside in the early 70's and I got to see the 917-10, the 917-30, and the IROC 911s race through those years. I was a Porsche street car enthusiast too. My Mom bought a Porsche 911SC when I was 17. When she retired and move to Hawaii, I bought the car. I started a progression of improvements on that car that led to PCA and autocrossing. Then it led to DE events. I raced motorcycle for several years but came back to Porsche and built the race car I have today. That car has progressed as well. My wife still has a street 911 that we both appreciate. Oh, she is the race car owner and she is my crew chief at the track.

So no, I certainly did no belittling of street car enthusiast. What I did do was provide an opinion on using a single MSD 6AL to power two coils. My answer has been the same all along. Yes, it will work. But it is not ideal because you halve the power to the spark plugs. There are reasons to go with a single ignition but the right way and the best way is to use two. Using a single ignition certainly should not be the standard way to do it. You on the other hand, did try to belittle me. Keep trying if you want, but it is not working.

I certainly did not advocate people spending more than they can afford, that they should upgrade to multiple adjustable shocks with coilovers, run slicks on the street, upgrade to super loud exhausts, or bump the compression of their engine so they need to run race gas. Where do all these pent up insecurities come from? Is me having the gall to disagree with you a problem for you?

I admit to having a "performance myopia" when it comes to Porsche cars. I don't think it is a negative. You know where I get that myopia? From Porsche themselves. It's the culture they have established and nurtured and it is a culture I am proud to be part of even if it is on the Club Racing level. Heck, I was part of it before I had my race car.

Originally Posted by Henry Schmidt

What happened to this thread is "performance myopia".
The inability to see the value in performance enhancements that do not directly relate to race track performance.

We see this type of myopia when the show car people talk about DYI restorations. "What? that's not the original color? I wouldn't own that car."

Or among dog show people..."What bread is that? Funny, your dogs ears aren't the right shape."

And even among the Teddy Bear collectors: "The articulation in your bear's right leg is 4 degrees off."

A few year ago I had a very nice collection of old Colts, some of which were duplicates. I decided to take some of the more worn duplicates (1890, 1905) and send them back to Colt for restoration. The gun forums dweebs exploded.
One guy proclaimed with passion "the patina had history!"

Most Porsche enthusiasts are not racers. Most couldn't care less about PCA, POC or even IMSA racing. They want to enjoy the spirited ride offered by a well tuned Porsche. Maybe carve through a mountain road at six in the morning before the local LEO sets up his speed trap. They work with what they have, trying to stay within their budget. They upgrade their shocks (but not often JRZ with coil over), they buy performance tires but they generally want tread, they upgrade their exhaust but still want to hear their stereo and they want a little more compression but still run street gas..
To belittle those enthusiasts because "that's not how they do it at the track" cheapens the Porsche experience for far too many enthusiasts.

[winders]

Henry,

Now, having said all of the above, it is those in the Porsche community that are pushing the performance envelope of the air-cooled cars that are advancing the technology and what is possible today for the air-cooled enthusiast.

This stuff does not just magically appear on the market. It was developed by people competing with Porsches at some level. That could be autocrossing or club racing. On the engine side you have people like Dick Elverud, William Knight, Pat Williams, Lynn Howel, Sol Snyderman, Jeff Gamroth, Peter Dawe, Jae Lee, Kevin Roush, etc., finding ways to extract more performance from engines Porsche stopped developing long ago. These guys aren't building engines just like they did in the 70's and 80's. No, they have moved well forward with ideas and technology.

It's racing customers like me and many others here who want faster and better handling cars that really drive this innovation. If it weren't for the customers wanting to go faster, there would be little reason to do this development work and no one to pay for it.

It's a great community and you shouldn't minimize the contributions of club racers by calling what they do "meaningless club events". Those "meaningless club events" drive a lot of innovation that becomes available to anyone in the community that desires it.

[Henry Schmidt]

Oh my god. Your passion and excitement for your hobby is soooo cute. I want to give you a big hug…
If I didn’t know better, your rant would lead me to believe you were on the verge of curing cancer. How in the hell has Porsche Motorsport survived without your racecraft? Don't get me wrong, I like teasing an apex just as much if not more than most but some noble adventure it is not.

As for show cars, dog shows and teddy bear collectors, they are analogies. That’s a literary tool used to illustrate by comparison, how one idea, method or thought process is similar to another. It's intended to illuminate ideas that might otherwise be missed by a narrowly focused mindset.

I’m sure that the Teddy Bear Guild is just as excited and passionate about their hobby as you are about yours…
"gentlemen start your engines" @ Laguna Seca is no different than “once around for the judges, please” @ Westminister. Accept maybe for the coverage. Westminister get millions of viewers.

[Mark Henry]

Originally Posted by Henry Schmidt

What happened to this thread is "performance myopia".
The inability to see the value in performance enhancements that do not directly relate to race track performance.

We see this type of myopia when the show car people talk about DYI restorations. "What? that's not the original color? I wouldn't own that car."

Or among dog show people..."What bread is that? Funny, your dogs ears aren't the right shape."

And even among the Teddy Bear collectors: "The articulation in your bear's right leg is 4 degrees off."

A few year ago I had a very nice collection of old Colts, some of which were duplicates. I decided to take some of the more worn duplicates (1890, 1905) and send them back to Colt for restoration. The gun forums dweebs exploded.
One guy proclaimed with passion "the patina had history!"

Most Porsche enthusiasts are not racers. Most couldn't care less about PCA, POC or even IMSA racing. They want to enjoy the spirited ride offered by a well tuned Porsche. Maybe carve through a mountain road at six in the morning before the local LEO sets up his speed trap. They work with what they have, trying to stay within their budget. They upgrade their shocks (but not often JRZ with coil over), they buy performance tires but they generally want tread, they upgrade their exhaust but still want to hear their stereo and they want a little more compression but still run street gas..
To belittle those enthusiasts because "that's not how they do it at the track" cheapens the Porsche experience for far too many enthusiasts.

I have to agree.

All I wanted was a cool and powerful engine and I know I'm leaving a lot on the table but I don't care. I have at least a 250hp 3.0 in a narrow body 914, I don't need any more freaking power. I know I could get at least another 30Hp maybe more out of it, but runs so ******* amazing that I'm not inclined to mess with it.

I also have a 2.6 type 4 engine 180hp in a 1700lb bug, 46mm ITBs, nickies, big cam, etc.,and it was real cool 15 years ago, but it come to the point where I don't like a street car that only runs in alphaN. I'm thinking of building a plenum system and de-tuning it to the point of making it more friendly on the street and to help make it quieter.

[KNIGHTRACE]

914 250 hp........ would be a blast and a lot of fun. I bring this up because I am trying to show support not challenge anyone.. This car is about 7.5 pounds per Hp. It is a very good fun number on the street.. However in my opinion that same 3 liter good motor in a 2500 lb is 10 pounds per HP and it is OK. In my my opinion the visceral fun cool car is more of an average car by todays standards. In 1996 I installed a 993 3.6 engine into my 1983 SC on a 915.. It was awesome, and only about 9 pounds per HP less power to weight being less power than Mark Henrys 914. I have been doing builds and things like that since early 90's. Thankfully today we have choices to fit the desire or need of each individual. I had a 3.5 turbo in the early 2000's that had an air to water intercooler, cams and a giant turbo I ran at 2 bar of boost for short street racing. If I could have afforded a 935 motor I would have given every dollar I had for it but it wasn't enough. Some would say "THIS IS NOT DIRECTED AT HENRY" that I wasted a lot of time and money. My reason for posting what I am is not to gain positive or negative judgment but to state that I feel I learned a lot of information that I could have not learned any other way.. I think 7.5 LB/HP car makes an excellent car. It is my goal to help people if I can and encourage everyone to appreciate all of the contributions to this forum from many intelligent people.

[Henry Schmidt]

William, I would never say that racing was a waste of time or money. To each his own.
My last race car project was a Riley DP that I bought with plans to install a twin turbo, air-cooled 930 engine in. I collected the parts and then changed direction.
The next iteration was a 996 GT2 engine. Bought that and sputtered again. The last iteration was a simple 996 based 4.0 GT3 engine.

My doctors suggested for a multitude of reasons that maybe racing wasn't a great idea, so I sold the Riley.

Wasted money? maybe but I spend goofy money on my hobbies as well.

My Riley was lasted raced as a Porsche V8 (Lozano , Cayenne motor) in Gatorade livery.







Now all I get to do is carve mountain and canyon roads in my street GT3 (soon to get a new 3.8 engine).