19 replies to this topic

[Carlos W]

Wasted spark is principally about doing away with the distributor which involves mechanical bits that can wear out and fal - you get a second spark anyway, off the rotor arm, so the potential for lost energy isn't that different.

 

On a 4 cylinder engine you need a minimum of 2 coils, they're packaged together with a common +ve, but they have 2 independent -ves that are switched the same as on an electronic dizzy.

 

As the spark is actually created when the voltage gets high enough to jump the gap, the cylinder under pressure with ionised fuel droplets between the sparkplug electrodes will have less resistance and is likely to be the first, probably only, one that fires .

Great explanation. Thanks

[MRA]

 

Is this even a serious question? 4 simultanious sparks..Also pretty pointless. If you want to experiment look for multispark technology.

Im not sure you have read the question!!!

 

So in a 4 cylinder engine on a wasted spark system the car has 1 coil.     or it would be coil on plug!!!

 

when piston 1 reaches tdc piston 4 is 180 degrees apart also at tdc but on the exhaust stroke not compression.

but on this system both spark plugs fire 1-4,   so in theory you could swap the HT leads around on 1-4 and 2-3.

 

!!!!!!!!!!!!!!!!

 

Yes you could, but why would you ?, also you will find that a "coil pack" is often multiple coils, ie 2, so 1&4 share the same coil as do 2&3 share the other coil, some even have one coil per cylinder within the pack which is one step away from COP (coil on plug)

[MIGLIACARS]

 

 

Is this even a serious question? 4 simultanious sparks..Also pretty pointless. If you want to experiment look for multispark technology.

Im not sure you have read the question!!!

 

So in a 4 cylinder engine on a wasted spark system the car has 1 coil.     or it would be coil on plug!!!

 

when piston 1 reaches tdc piston 4 is 180 degrees apart also at tdc but on the exhaust stroke not compression.

but on this system both spark plugs fire 1-4,   so in theory you could swap the HT leads around on 1-4 and 2-3.

 

!!!!!!!!!!!!!!!!

 

Yes you could, but why would you ?, also you will find that a "coil pack" is often multiple coils, ie 2, so 1&4 share the same coil as do 2&3 share the other coil, some even have one coil per cylinder within the pack which is one step away from COP (coil on plug)

 

No im not doing this!!!!!!!!!!!!!

As in the first question <thinking out-loud> and curious to find out if my thoughts were correct.  And thanks to some members on here my question has been answered and yes its what I thought!!!!

[tiger99]

No, the coil secondary has two ends and is not grounded or tied to one of the low voltage terminals, so both plugs need to spark. Breakdown will always be easier in the cylinder at the end if the exhaust stroke, where there is minimal gas pressure, and it is already hot (not yet cooled by incoming charge) and probably partially ionised.

The voltage drop at the gap of the exhaust/inlet plug will be much less than at the compression/power stroke plug, and as the currents are necessarily the same (less some minor differences due to capacitance to earth) the energy at the rising stroke plug (proportional to the square of voltage) is much higher than in the inactive cylinder, so the hotter spark is where it does most good.

A complication is that in the spark plugs the polarity of the initial edge of the firing waveform matters, so the primary circuit really ought to be driven with one polarity to fire cylinder 1 and with the opposite polarity to fire cylinder 4, so the voltage at each plug is the correct polarity. That is probably not done in cheap, nasty systems, which may be one of the reasons why wasted spark systems are not in favour with some people.

If you do have polarity switched primary circuits, swapping plug leads will give you reversed polarity in the active cylinder and a possible drop in performance.

[MRA]

 

 

 

Is this even a serious question? 4 simultanious sparks..Also pretty pointless. If you want to experiment look for multispark technology.

Im not sure you have read the question!!!

 

So in a 4 cylinder engine on a wasted spark system the car has 1 coil.     or it would be coil on plug!!!

 

when piston 1 reaches tdc piston 4 is 180 degrees apart also at tdc but on the exhaust stroke not compression.

but on this system both spark plugs fire 1-4,   so in theory you could swap the HT leads around on 1-4 and 2-3.

 

!!!!!!!!!!!!!!!!

 

Yes you could, but why would you ?, also you will find that a "coil pack" is often multiple coils, ie 2, so 1&4 share the same coil as do 2&3 share the other coil, some even have one coil per cylinder within the pack which is one step away from COP (coil on plug)

 

No im not doing this!!!!!!!!!!!!!

As in the first question <thinking out-loud> and curious to find out if my thoughts were correct.  And thanks to some members on here my question has been answered and yes its what I thought!!!!

 

never said you where :)  just asked why ?