I keep hearing about guys putting MSD 6a packs on their leading coil. Why dont you also have it on the trailing coil, is it dumb/pointless, too much spark??, i dont know. What is a good ignition coil to get, and how many should i get (2 msd 6a's, one leading, one trailing?)

 

The trailing is mostly for more complete combustion for lower emissions. The car decent without trailings, but pretty bad without leadings, so take that as an idea as to which affects combustion most.

The 6A is a CDI box: a capacative discharge ignition. below 3000 rpm, it sends multiple sparks, and above 3000, a single, long lasting spark.

A coil is something completely different. To run coils, you'd need four: two trailing and two leading (although I have heard of MSD's motorcycle coils being used as leading coils).

Some people have run 3 CDI boxes (that's $600!), one for leading, one for each rear trailing plug. This is mostly done in all out race motors, as one method to prevent detonation. Two are required on the rear since they do not have a single igniter (and thus no wastespark, like the front coil).

For you, your best bet would be to run a single CDI box on your stock leading coil.

 

Ah, Dah....

I unpluged my "spark plugs" so no one would steal my car while gone on a long trip. Only did one set. Stuffed the wires where no one would notice them.

When I returned I drove the car many times. Went to fill window washer. Heard funny sound. Open hood.

Plug wires pulled from trailing coils were out and stuffed just were I left them. The wires were attached to the plugs but 6 inches away from the coils. The coil ends of the plug wires were sparking against the body.

How could that happen? Induction from the leading wires?

Runs better with training plugs working! But ran OK without them.

Can I save $9 and only replace the leading plugs?

 

Great info Sean. 5 stars for you!!

 

As for sparking, I'm not too sure. My guess is since plug wires are such excellent conductors and FC's are known for bad grounds that the engine was using the plug wires to ground itself. However sparking does not seem to be " the shortest path".

As for saving $9... Its $9 to help prevent carbon build-up by a more complete combustion. Carbon build-up kills engines. If $9 is too expensive for you, don't replace the plugs at all. For god's sakes, its $9!!
You'd better not have a $800 stereo or any **** like that, and the thing had better be bone stock to comlain about $9.

 

has n e one heard of a sci ( sport compact ignition ) made by msd for higher reving engines?
if so how good is that ?

 

ANYONE HEAR OF IT ? ? ?

 

I have it on my Honda Civic..It is a Nice ignition..I like it..I have the Msd 6al on my FC...I can't tell the difference..I paid 180 dollars for the Sport Compact ignition and 50 dollars for the 6AL, bought it from a friend...The Sport Compact dosen't have the slot for the Rev Limiter chips....But Msd does make one with the slots I believe...All around I like Msd products...That is all I have ever used...Oh yea Got my Sport Compact ignition from Summit Racing if that helps...

 

Well I run 2 Crane Hi6 (similar to MSD 6A, but better spec) CDI units and two coils for my leading plugs (one on each leading rotor!). This is a bit over the top but the results are well worth it.

Most pros use CDI, it has been used in F1 since the early 80's and realy all race cars without it are just plain loosing power and efficiency, biggest difference on road is the reduction in fuel economy and smooth running compared to transistor ignition (stock)

 

Fuel economy goes up, not down. A reduction in fuel use, but an increase in fuel economy.

 

SO HAS N E ONE SEEN OR HAVE N E PROOF OF THE SCI ON A 7? n e differences? thanks and sorry 4 the caps

 

I can just spew out what the SCI is for: immensely high revs, and specifically designed for 4 bangers: there is no 8 cylinder wiring config.

Unless you are seeing above 10K, then I'd stay with just a normal MSD 6A. If you are exceeding that RPM amount, then you've obviously built a race motor, and should be using something along the lines of 3 DIS's or some digital 7 or up boxes to get the best system.

I recommend the 6A for a rotary, but the SCI would work fine. They would both do the same thing.

 

It's just an MSD 6A put into a shiny box - get a 6A and save the rest of the money.


-Ted