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Coil on plug v wasted spark
Steelman - 26/9/08 at 07:38 AM

What's the difference and which is better.

Mr Whippy - 26/9/08 at 07:54 AM

never been one for the coil on plug, not a nice place for something like a coil and I've seen plenty fail, including mine and my neighbours volvo’s, damn expensive new as well. Much prefer my coil mounted on the body with rubber mounts.

Leckyman - 26/9/08 at 08:02 AM

Hi, there seems to be a lot of confusion about this , it's possible to run coil on sticks on a wasted spark system (Early Yamaha R6). The question should be which ignition system works best, single firing or waisted spark, in theory single spark should as if your firing two plugs and one isn't on the compression stroke you are halving the availiable spark to the the cylinder doing the work. In reality on our dyno we have tried this on numerous systems (car and bike) and found absolutely no difference at any point on the power/torque curve, manufacturers like coil-on-stick (especilaly on bike engines) as it saves a big chunk of space where they can put stuff to aid performance (bigger airbox etc)

Hope this helps

britishtrident - 26/9/08 at 09:48 AM

You can have both some Rover plug top coils have short lead to a second plug.

[Edited on 26/9/08 by britishtrident] Rescued attachment 01.jpg
Rescued attachment 01.jpg

martyn_16v - 26/9/08 at 10:02 AM

quote:
Originally posted by Leckyman
if your firing two plugs and one isn't on the compression stroke you are halving the availiable spark to the the cylinder doing the work.


No, you're not. The very low cylinder pressure at the time of the 'wasted' spark means that very little energy is actually used in that spark, the vast majority goes through the other one.

MikeRJ - 26/9/08 at 12:20 PM

The advantage of COP is the lack of HT leads to break down and radiate, and the fact that the entire coil is buried in the engine, providing superior shielding.

r1_pete - 26/9/08 at 02:09 PM

quote:
Originally posted by martyn_16v
quote:
Originally posted by Leckyman
if your firing two plugs and one isn't on the compression stroke you are halving the availiable spark to the the cylinder doing the work.


No, you're not. The very low cylinder pressure at the time of the 'wasted' spark means that very little energy is actually used in that spark, the vast majority goes through the other one.


Correct, those spark intensifiers which used to be sold as performance upgrades were little more than a device which introduced an air gap in the HT for the current to jump, usually between the coil and distributor. Much the same effect with a wasted spark.

Leckyman - 26/9/08 at 04:40 PM

Ladies, Gents, my original post said "in theory" and also said we have seen no real difference between the two systems, I agree with you, I was just trying to help the topic originator by expalining some misconceptions and a bit of the theory : )

Also, stick coils tend to be reliable in a normal road bike/car, they become unreliable in other applications becuase of the increased disturbance as petrol heads (thats us) remove check/replace spark plugs on a more regular basis, the rubber insulator breaks down with the constant pulling out and pushing in within the cylinder head, a "little" non conductive graese helps, we have never had a coil plug fail, thats in 9 years.

Hope this all helps.