? ? ? Spark Plugs For A Waste Spark Ignition

[Banjo]

Hi Guys,

Interested to know from anyone out there who has a waste spark ignition system fitted on their 4K or 5K motors, what brand & model "waste spark" spark plugs they have found suitable.

 

Cheers Banjo

[altezzaclub]

Now why would you fit waste spark Banjo?? Isn't that where it fires every cycle?

 

So you can simplify the ignition setup?

 

I haven't heard of anyone fitting it.

[snot35]

It would be twice every cycle wouldn't it? Once as god intended and once doing nothing in the exhaust cycle. It's a valid thing to do if you're wanting to do coil on plug but your ECU only has enough ignition drivers to fire two coils. You end up "sharing" a coil with cylinders at opposite ends of their cycle (1 and 4, 2 and 3).

 

I'm curious to see your setup? :)

[Banjo]

There are a number of guys in Rollaclub that have waste spark ignition setups. One of the best executed ones I have come across is Brodies little project in S.A. a few years back. He's a perfectionist, and his mods are just beautiful.

 

http://www.rollaclub...__ waste spark

 

 

The waste spark system does simplify the ignition system considerably, with the best result being the removal of the need for the distributor cap, rotor button etc.

 

You still have the option of using the distributor points or reluctor, to trigger an ignition module to fire the coils, but it does provide you the chance to get rid of the distributor altogether, if the ignition module has programable advance curve & MAP load retard facilities.

 

The best opportunity offered is to trigger the ignition from the flywheel, rather than the camshaft driven distributor. This has massive advantages on older cars like most of our K series engines. The "slop" that is created in the drive between crankshaft & points in often underestimated.

 

That "slop" in timing chain and distributor drive gear, results in an inconsistent firing point, and if you've ever used a timing light on the timing marks on the front timing chain cover & pulley, you've probably seen it jumping around up & down a few degrees.

 

When you switch to crankshaft triggering, that mechanical induced instability into the triggering point is eliminated altogether. If you read Brodies build, you'll see he used a toothed trigger wheel fitted to the front of the crankshaft pulley. That is probably the most popular way of triggering. Most ignition modules accept toothed wheel sensors with a missing tooth indicating TDC no: 1 cyclinder as a reference point for the whole system.

 

When I trigger off the crankshaft, the timing light indicates a rock steady timing mark at the crankshaft pulley. All other things aside, it changes the smoothness of the engine instantly, and the ability to be able to program advance curves lets you get the most out of the engine. Remember these engines were designed with performance to limit warranty claims & increase reliability. The number of KE series Corollas on the road still, is a testiment to that. The igniton system was one of the major ways of controlling/downgrading the performance of the engine.

 

I am experimenting with another way of cranshaft triggering which is very simple. I trigger off the flywheel, using rare earth magnets embedded into small holes drilled vertically into the narrow rim of the flywheel between the ring gear & the clutch face.

 

 

A Hall Effect sensor picks up the signals beautifully. I've even tried a linear Hall Effect sensor that can sense the difference between a South pole & a North pole, so that a common sensor can pick up all 1-4, & 2-3 triggering points. The system works well with a waste spark system, but is just as easily utilised with sequential firing each spark plug one at a time, which allows smaller coil on plug arrangement.

 

If anyone is interested, I'll put up a few photos, as I have the 4K engine I'm experimenting with on an engine jig I built a few years ago.

 

 

I take all my measurements at the flywheel, where I have a nice big degree wheel fitted.

 

It's a great way to learn, and after I've perfected the ignition setup, I'll move onto incorporating an EFI setup, so I can incorporate all mods on the 5K I have awaiting.

 

Cheers Banjo

Edited February 28, 2013 by Banjo

[altezzaclub]

holy sht Batman! That is keen!

 

Just a restricted water pump on the gearbox output & you'd have a private dyno!

 

Hmmm... It might get rid of the lurch in over-run I have...

 

I've even tried a linear Hall Effect sensor that can sense the difference between a South pole & a North pole, so that a common sensor can pick up all 1-4, & 2-3 triggering points. The system works well with a waste spark system, but is just as easily utilised with sequential firing each spark plug one at a time, which allows smaller coil on plug arrangement.

Now THAT would be nice- So we have a crank position sensor, a MAP sensor, individual coils, a knock sensor, water temp sensor and air temp sensor, a programmable ECU... on Kehnin quad carbs! ..and I thought the ultimate K motor was philfrederick's twincam!

[Banjo]

Just a restricted water pump on the gearbox output & you'd have a private dyno!

 

The idea had crossed my mind seriously. It should be possible to create a load equal to the 4K with a restricted agricultural type water pump & a couple of 44 gal drums as a resevoir. It would be nice to be able to fine tune the engine out of the car in a totally controlled enviroment. Only other thing I would need would be one of those large industrial fans in front of the radiator to produce the forced air you get through the radiator whilst driving.

 

Cheers Banjo

[snot35]

Love your work! I've been mulling over a test stand for an engine that I have, but I think I'll need to put it in before the season starts. Keep us posted with what you're up too, I like your approach to things!

 

P.S. Can't help you with the plugs I'm sorry! :)

[ke70dave]

Very cool setup.

 

I had noticed when playing with a timing light on older engines that the mark jumps around. never occured to me it would be because of hte slack in the chain/points/dizzy setup!!

 

I'm not convinced that spark plugs for wasted spark would be any different to normal spark plugs?

[Banjo]

The test stand is a no brainer. If you've ever done major work on an engine, fitted it back into the car, tried to start it & found you've stuffed up big-time somewhere internally, & have has to pull it all out again, to rectify; you'll appreciate the confidence that the engine runs well, before it's fitted to the car.

 

I built the stand on a Saturday afternoon a few years back. Three or four 200mm x 50mm hardwood planks I got from the local nursery supplier. $ 20 worth of coach screws & bolts & nuts from Bunnings. Thats about it. All the other Corolla bits I had lying around. KE70 front cross member & radiator. The accelerator is a height adjuster off an old Rover lawn mower I scrouged from the tip. It allows you to set the revs at a constant setting with both hands free to tune. A quick coat of black fence paint & it does the job.

 

 

 

Has some heavy duty castors on the side rails, so you can "park" it easily in the garage. Four blocks fit under the corners, when in use to prevent it moving around.

 

Cheers Banjo

Edited February 28, 2013 by Banjo

[Banjo]

You can use the "same" spark plugs in waste spark systems, but the degrading/errosion of the spark plug centre terminal is different in each plug, as HT current goes from outside to centre pin of one spark plug, & centre to outside on the spark plug in the "mated" cylinder. It's the outside electrode that errodes fastest, when the HT current is reversed. Originally, when all the plugs were the same, you would swap "mated" cylinders plugs around at service to extend their life. Now there are special spark plugs pairs with one made with the outer electrode made of identical material to the centre pin.

 

This is as good a description as you'll find regarding waste spark systems.

 

http://en.wikipedia...._component_life

 

Read the section on Effect on Component Life

 

Cheers Banjo

Edited February 28, 2013 by Banjo

[Banjo]

For those that like researching these subjects, there was a good thread over on Toymods a few years ago, regarding the advantages of sequential firing of spark plugs vs wasted spak setups.

 

http://www.toymods.org.au/forums/tech-conversions/10670-wasted-sparks-vs-sequential-spark.html

 

Cheers Banjo

[Banjo]

This article from NGK Spark Plugs describes the need for special spark plugs for wasted spark systems far better than I can.

 

It is important to know that in a waste spark ignition, both the center firing electrode and ground

electrode will see gap erosion. In plugs with a positive polarity, most wear will occur at the center

- firing electrode. Plugs with negative polarity will experience more wear at the ground electrode.

As a result of this, vehicles equipped with waste spark ignitions often use double precious metal spark plugs, such as the Laser Iridium or Laser Platinum. These dual precious metal plugs feature either iridium or platinum on the center firing electrode and platinum at the ground electrode. Because these electrode materials are denser, gap erosion is reduced, allowing a longer service interval. Being that these materials are denser, this will reduce gap erosion, thus leading to a much longer service interval. The use of nickel-alloy or single precious metal spark plugs in vehicles equipped with waste spark ignitions will result in more aggressive gap erosion and shorter spark plug life.

 

 

The full article can be found here

 

 

http://www.ngksparkp...k_Ignitions.pdf

[Banjo]

Hi Guys,

A few of you have asked for some "picies" of the rig I have got setup in my garage for the waste spark ignition experimentation I'm having fun playing around with.

 

 

 

 

 

 

 

 

 

 

 

 

 

We all like looking at picies don't we ?

 

Cheers Banjo

[altezzaclub]

Lovely! Get that waterpump on it!

 

Swap to 32/36 carb, then SUs, then a DCOE.. No wait- inch and 3/4 exhaust, then a 2" with three different mufflers! No, hang on, a 270deg cxam, a 275 deg cam and the 280deg cam!.....

 

nah- just put wheels and a seat on it for the grand-kids!

[Banjo]

I've narrowed down the spark plug selection to NGK BPR5EIX (Iridium) or NGK BPR5EGP (Platinum). These precisious metal plugs resists the erosion created by using the waste spark system where the HT current passes through the "paired" cylinder plugs in different directions.

 

However, I've had a chat to Brodie in S.A. yesterday, who went through this whole thing several years ago. His findings were that . . . . . .

 

NGK was the only plug worth considering.

 

Unless the fuel mixture is near perfect, the precious metal plugs foul easily, & are hard to clean back to 100%.

 

Re reverted back to good olde cheap copper NGK plugs, and just changed them when needs be, as he doesn't put a lot of klms on his KE30.

 

A bit of research indicated that back in the 1980s, when waste spark first started to raise it's head, it was common, to swap the two spark plugs around, on the "paired" cylinders, so that the erosion was even on both electrodes, over time.

 

However Brodie came up with a great idea which provides the simplicity of the waste spark system, without the issue of the erosion of plugs. He used four individual CoP motor bike coils on his 3K. I assumed incorrectly that he fired them sequentially, but he tells me he used a waste spark system where he fired the coils in pairs, so it is a waste spark system.

 

 

Beautiful work Brodie !

 

Read Brodie's thread here . . . http://www.rollaclub.com/board/topic/47900-brodies-ke30-2door-supercharged-intercooled-megasquirt-cop-ignition/page__p__605291#entry605291

 

The only disadvantage is that you need four (4) ignitor modules, one for each coil. However very minimal ignitors can be utilised, because each ignitor is only firing one smaller motor bike coil, which are designed for much higher RPM than we'll ever see in a 3, 4, or 5K engine.

 

Because each spark plug has a seperate coil there are no issues with erosion

 

I've been using the Bosch BIP373 Mosfets as ignitors for the coils. I couldn't get them here in Australia, so I bought some from DIY Autotune in the USA. They are great, being almost indestructible, with overtemp cutout & current limiting. The nice thing is they can be driven by the output of an ordinary CMOS chip.

 

So although the erosion of plugs is no great issue as yet for me, I may finish up using four motor bike type coils.

 

Wouldn't it be great if I could find four coils small enough that they could all fit inside the original distributor cap.

 

Cheers Banjo

Edited March 2, 2013 by Banjo