I had one in my jeep several years ago because everyone said it helped prevent plug fowling from all the low RPM driving and increased torque. I never had a problem with the system or the jeep in general, but I am not sure it really did anything...

Can someone explain how these work, what they do, and if it is a good idea for a 914? If it is, whats the best system?

I am running a basically stock strong running 73 2.0L with DJet.

Thanks!

Has this already been beat to death and I missed it?

They are designed to be used with their respective coils to throw a hotter spark to prevent fouling. Also to allow for a larger plug gap to better ignite the fuel/air mixture. Since they are CD systems, they build up a charge faster.

Some systems throw multiple sparks to further burn the air/fuel mixture on the power stroke, but they generally only throw multiple impulses in the lower rpm ranges.

That's my take ...

Beat it further if you wish.

I noticed that most of them only throw multiple sparks or a "longer" spark (20 Degrees of crank rotation up to 3000 RPM. I have been watching my tach and I don't see it below 3K very often. I guess thats what made me ask the question. In the jeep I was hardly ever OVER 3k.

Are they a good option for a stock motor? They claim increases in HP, torque, and fuel economy... I am guessing that is as a result of a more complete burn and fewer misfires.

I guess what I really want to know is is it enough to make it worth the money in our cars... or is this another tornado?

stock 2.0, right? snake oil
2.4 turbo, good idea. 2c

Not really a Tornado as they do what they say they will. Increase in HP/torque is questionable. Better fuel economy ... probably.

Are they worth it? .... what is BLING with some benefits worth to you?

My fours I ran with a Crane/Allison Optical system, even the race cars. My sixes I run with the stock CDI system. I do have a Crane HyFire system I will eventually install on something, but BLING in the Box is worth one in the hand.

They are decent systems ... just depends on what you want to spend money on. They have their advantages.

I do know you should never yank the coil wire off of a MSD

I had an MSD-6A with a Crane fireball Optic in the 050 distributer on a 2056
With Webber 40 carbs. I would intermitently, out of the Blue just loose
spark. Sometimes I would just move the opic wire to the dist. and away I'd
go. Sometimes I would burn the rotor accross the top. A few times the
optic eye had to be replaced to get started. It was neccessarty to carry
extra parts with me. I have deleted all this last Fall and installed Pertronics
No problems since this time.

I do notice that the motor does not have the KICK it use to after 3,000 RPM
and power over 5,000 RPM like it use to. Have thought about hooking up
the MSD again but can any body tell me, can these units ( MSD ) be tested?

My 2 cents and TIA for listening

A good rule of thumb is stock ignition for stock engines using components that are in GOOD shape. If you hot rod it as mentioned above, then a MSD box, coil, 9mm wires and such is the way to go. On a D-Jet systems you will need the stock distributor with the trigger points and pushing 15 to 20K voltage through a stock Bosch distributor cap and rotor will cook it in no time.

I'm done with the boxes. We tried several capacitive systems and not a single one made even a tenth of a hp more power or torque than a simple optical pickup with a plain-jane coil. Didn'e even matter what coil. We did our testing on Jakes chassis dyno with repeatability within 0.1hp. It also made no difference in how easily the engine started or it's resistance to plug fouling. This data was gathered over two seasons of racing.

Dave Finch's F-Prod 914 won the runoff's in 2005 with a 009 with points and condensor and a Blue coil. Saw it with my own eyes.

One of the boxes (a Mallory) did however fail and cost us a race. I have a perfectly good, very low mileage MSD 6A box for sale that I pulled out of the car after yet another dyno run confirmed that it made 0.0% difference in the 4,000-8,000RPM rnage that we are concerned with. No reasonable offer refused.

The only good thing about MSD is your points last longer but if you use the inductor
for the tack all bets are off, above 4000 prm its a single spark not multi spark.
plus its another part that can go bad!!!

I also use a msd 6al on my hunting jeep truck because it goes around real slow all the time and it keeps the plugs firing better longer. I would like to try one on my vac case tractor as it seems to be too rich.

msd seems to mask faults in a crappy engine

It might actually have some merit on a low speed engine. It does have some value on a total loss charging system, (no alternator) as it continues to deliver down to 10volts. But we don't see bat voltage that low with our Optima yellow top, so I'm done with the boxes!

I recommend that if you use one on the street that you have a way to by pass it quickly so you don't get left on the side of the road.

I've always thought this on VW engines, the first time I installed a customer supplied Jacob's my first reaction to their claims was

Now that I'm building a /6 everyone says you have to run at least a factory CDI or a MSD,etc.
Do you still say BS?

One thing is if I decide to switch to SDS FI and ditch the Webers I can run a crankfire through a MSD and save some coin...plus I have a MSD and magnacore wire set that was given to me by a fellow member.

Mark I can only speak to the experience we had with our 4 banger.
I'm of the opinion that a good coil is probably capable of reloading fast enough for a 6 banger at any reasonable RPM range.

As far as ignitions go I say the simpler the better. Crank fire straight to a coil bank would be the ultimate (short of a mag!). A freebie MSD box would be tempting, but like I said in an earlier post I would have a system in place that would by pass it quickly if it is for street use. If a race car I would make sure I could switch to a back up on the fly, or just don't fool with it.

one could speculate that Porsche went to a cdi box on teh six because they had a tendancy to load up at lower rpm.

OK. so if we ditch the msd on the race car, what do you use to limit rpm?
we run a foley-tweeked mallory dizzy...currently thru a Hyfire box
I agree with K.I.S.S....less to fail if its not needed
and of course: what does it weigh?

I don't bother with the rev limiter. After hitting it last year and breaking a fan I put a module in that was well above our redline.

I have my shifter/linkage/tranny sorted so well that I don't miss shifts, so the heck with it. I would like to have one for worst case scenarios, but the baggage that comes with it is not worth it IMHO.

When I chucked the MSD box with the mounting plate, splash shield and vibration dampners I shed a few ounces over 3lbs.

I use one but not for any of the advertised reasons. For me it is just a simple way to drive the coil when controlling spark with megasquirt that did not require extra circuitry. It seemed like the studier solution and probably cuts down on EMI as well by not having the coil tied directly to the ECU.

On a car that has an ignition system that already works fine i don't see where there would be an advantage to a CDI system. All spark does it light the fire, and if you are already lighting the fire with your current setup there is nothing more for a hotter spark to do. I could maybe see a need in a motor that for whatever reason (mixture/compression/whatever) was having problems jumping the plug gap, but if Len is saying he is not seeing a difference in his race motor i am guessing any motor that would actually require one would be pretty extreme.

Sean, MSD makes a lone rev-limiter that is completely independent of a regular Electronic ignition box.. Semms like a pretty straightforward hook-up as well..