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Waste Spark Vs Ignition Boost System?

abulurd

By abulurd,
in Engines & Forced Induction

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Lithium Grand Master

Lithium

Posted
Posted (edited)

I'm not as much of a fan of the wasted spark idea, I had a fair amount of bad luck with trying it on mine and have swapped back to the factory coil on plug with some better insulation which has worked a trick for me so far. I think the main advantage of wasted spark setups is the fact that the coils are not mounted on a nicely earthed bracket which tempts fate as sooner or later the charge in the coil is going to find a way through the epoxy to ground instead of waiting until it should be jumping the spark plug gap.

Edited by Lithium
Crans Mentor

Crans

Posted
Posted (edited)

Cant you get the best of both worlds?

External coil packs that don't waste none of those rare sparks?

Motec coil system? Or something similar?

Or is it the fact you can use cheap holden coils?

Edited by Crans
daisu Mentor

daisu

Posted
Posted

to me wasted spark seems a bit of a... waste.

Half of the potential spark energy is being wasted on the opposite cylinder, and the coils have to fire twice as much which results in shorter life span and could develop problems in the higher RPM range if there is not enough time for the coils to charge.

Personally I'd be looking at individual coils (remote mounted)

Mr Jollwah Community Regular

Mr Jollwah

Posted
Posted
to me wasted spark seems a bit of a... waste.

Half of the potential spark energy is being wasted on the opposite cylinder, and the coils have to fire twice as much which results in shorter life span and could develop problems in the higher RPM range if there is not enough time for the coils to charge.

Personally I'd be looking at individual coils (remote mounted)

Agreed for the dwell time issue and coil longevity etc etc. But the amount of spark energy expended firing on the waste cylinder is not half.

As the density of the mixture in the cylinder effects the resistance at the plug.

Waste spark will never be as good as individual coils, but it is cheap and better than the ol distributor days. It is a backwards/sideways step on a skyline tho.

MBS206 Grand Master

MBS206

Posted
Posted
Agreed for the dwell time issue and coil longevity etc etc. But the amount of spark energy expended firing on the waste cylinder is not half.

As the density of the mixture in the cylinder effects the resistance at the plug.

Waste spark will never be as good as individual coils, but it is cheap and better than the ol distributor days. It is a backwards/sideways step on a skyline tho.

Explain how it's a backwards/sideways step on a skyline?

I run INDIVIDUAL COILS per cylinder, but run wasted spark...

Wasted spark is not just about having 1 coil, for 2 cylinders, it is PURELY about firing 2 or more spark plugs, when only one is actually making the power.

Lithium Grand Master

Lithium

Posted
Posted
Explain how it's a backwards/sideways step on a skyline?

I run INDIVIDUAL COILS per cylinder, but run wasted spark...

Wasted spark is not just about having 1 coil, for 2 cylinders, it is PURELY about firing 2 or more spark plugs, when only one is actually making the power.

Then you don't have an individual coil per cylinder, you have two cylinders for every coil. Your coils compared to an individual coil per cylinder is going to be jumping two gaps each time it fires, granted one of them is going to be given as much resistance but it still has to jump the gap. The real hard work is going to be the fact that it has to build up and discharge twice as much as a individual coil setup - my stockers are charging at discharging over a .9mm gap up to a max of 7500 times a minute. With wasted spark they are jumping two gaps 15,000 times a minute to achieve the same job.

daxter Enthusiast

daxter

Posted
Posted

I'm running wasted spark and find my car runs better then it ever did on factory coils. Car never miss’s a beat and revs hard to redline. Also the coil unit runs cooler as its mounted away from the engine, I can hold my hand on the coil unit after a hard drive.

daisu Mentor

daisu

Posted
Posted
the amount of spark energy expended firing on the waste cylinder is not half.

As the density of the mixture in the cylinder effects the resistance at the plug.

Wouldn't the resistance at the plug in the opposing cylinder (end of exhaust stroke) be less than the resistance at the plug of the cylinder that is on the compression stroke? If so, more than half of the spark energy would be on the wasted side.

But, surely these things would've been taken into account when designing coils for wasted spark systems.

I'm running wasted spark and find my car runs better then it ever did on factory coils. Car never miss’s a beat and revs hard to redline. Also the coil unit runs cooler as its mounted away from the engine, I can hold my hand on the coil unit after a hard drive.

Did you try comparing the wasted spark to individual coils remote mounted? Are your wasted spark coils new? Unless you only change one variable at a time you can't really compare them fairly.

The best way to test with be with a spark gap tester.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted
Did you try comparing the wasted spark to individual coils remote mounted?

Are your wasted spark coils new?

Unless you only change one variable at a time you can't really compare them fairly.

Exactly - my bet is he went from a setup that wasnt properly working... so of COURSE a correctly working setup (regardless of how) is going to be better than a mediocre one.

I had 370rwkw, stock ignition... but then... my setup was working correctly.

daxter Enthusiast

daxter

Posted
Posted
Did you try comparing the wasted spark to individual coils remote mounted? Are your wasted spark coils new? Unless you only change one variable at a time you can't really compare them fairly.

The best way to test with be with a spark gap tester.

No I haven't tried different set-ups. Here in NZ most track/drift Skylines are running wasted-spark, decided if there good enough to handle been thrashed on a race track then good enough for my road car. Ive been running with the setup for over a year and never had any problems. There a proven setup that works (like many other coil setups) and nice on the pocket $200NZ.

Lithium Grand Master

Lithium

Posted
Posted
No I haven't tried different set-ups. Here in NZ most track/drift Skylines are running wasted-spark, decided if there good enough to handle been thrashed on a race track then good enough for my road car. Ive been running with the setup for over a year and never had any problems. There a proven setup that works (like many other coil setups) and nice on the pocket $200NZ.

Stock setup was better on the pocket, came with the car :) IMHO a road car would probably be harder on the ignition system overall, the things that go wrong with Nissan ignition systems are more to do with lots of use rather than high revs/load. I'm running >150,000km original coils and ~17psi on an RB25 and there is absolutely no hint of weak spark.

abulurd Rookie

abulurd

Posted
  • Author
Posted

I'm not chasing power so much at the moment as trying to get rid of the sputtering at around 5-5500 rpm. People keep telling me it's probably my coils but after reading a bunch of stuff in this forum I am starting to think it is more of an air/fuel problem ... or possibly 02 sensor?.

Theres only 1 place in NZ that does nistune and they are in Christchurch .. I am in AKL so I am flying quite blind at the moment.

But yeah if it is spark I was looking mainly for the cost . New coilpacks are like $1000 - $1200 over here and a wasted spark setup is 200-260

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

O2 has nothing to do with it under load.

Its probably AFM, could also be coils... just try find someone to swap with :)

How can they cost $1000? Just buy from a SAU trader and have it shipped... it couldn't be more than $600

Mr Jollwah Community Regular

Mr Jollwah

Posted
Posted
Wouldn't the resistance at the plug in the opposing cylinder (end of exhaust stroke) be less than the resistance at the plug of the cylinder that is on the compression stroke? If so, more than half of the spark energy would be on the wasted side.

But, surely these things would've been taken into account when designing coils for wasted spark systems.

Remember that the spark must jump both gaps to complete the circuit. Therefore the electrical potential must build up higher in the cylinder with the highest resistance to spark, inorder jump the gap and complete the circuit.

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