New Jetinetics Total Loss system

[WFO Speedracer]

thats what i thought


does he mean one spark insted of two = twice the battery life?



the only real performance advantage i can see from a dual channel is that you can retard or advance different cylinders

I believe he is referring to the lost spark of the stock system on the exhaust stroke of the other cylinder.

 

[Matt_E]

I believe he is referring to the lost spark of the stock system on the exhaust stroke of the other cylinder.

Bingo - that there is an advantage of running two dedicated coils.
The stock coil fires both plugs at once, so they have to share that energy.
Not so with dedicated coils.

 

[WFO Speedracer]

Except that I've never heard of anybody doing that. (Not saying it's not happening)



True, but either way "charge time" is not something you worry about with a coil.

Agreed electricity travels pretty damn fast. :sneaky:

 

[ATS_Aaron]

OK, we've got lots of plumbers here so let me try and make a better analogy.

Think of the coil as a BUCKET.

The CDI (stock, MSD, ATP, whatever) has to fill the bucket with energy. The catch is that the bucket has to be emptied to fire a spark. So the CDI has to start refilling the bucket everytime the spark fires.

The ATP has has to empty it's bucket twice per revolution.

The Multichannel MSD has twice as much time to fill it's buckets.

If you look at it in degrees of rotation the ATP has only 180 degrees of rotation to fill it's bucket before it gets emptied.

The MSD has a full 360 degrees to fill it's bucket.

Coil charging time is not instantaneous. It is important. It is exactly why Ferrari ran dual distributors on my 308, There was not sufficient dwell time to charge the coil to fire 8 cylinders at 8000 rpm, so they added another distributor and wired the car like two 4 cylinder engines. Voila twice the components meant 1/2 the work. This is on a WEAK 3000cc engine making only ~40hp per cylinder.

Aaron

 

[Matt_E]

Mkay. :wavey:

So is there reduced spark energy at higher RPMs then?

 

[ATS_Aaron]

Yes

 

[Matt_E]

I won't argue the point any further. We'll disagree. :veryhappy:
Inductors attenuate high frequencies, not low frequencies.
Voltage change in a coil is instantaneous (current is not).
I'll leave it at that.

 

[junkyardj]

Except that I've never heard of anybody doing that. (Not saying it's not happening)


never heard of retarding the drive cylinder ??

 

[Matt_E]

Not in Standups, no.

 

[ATS_Aaron]

From Hod Rod magazine:

DWELL

While electricity itself moves fast, it takes time for the changing magnetic fields in the coil to develop the full potential current and voltage. This is a way of saying that the induced voltage (stepped up voltage) does not develop instantaneously. To keep things simple, let's think of the coil as an energy storage device that can be "charged up" and "discharged" in a manner similar to a battery. It takes time for the coil to charge to its full potential, a condition we will call saturation. Similarly, it takes time for the coil to discharge some quantity of its electrical energy as it fires a spark plug.

The time that the ignition system gives to the coil for charge-up is called "dwell." With a points ignition system, dwell is fixed and is measured in terms of degrees of distributor rotation, typically 30 degrees for V8 engines, which is 60 degrees at the crankshaft. As engine speeds go up, the crank rotates faster and faster, and quite obviously it takes less time to spin through 60 degrees of crankshaft displacement. Therefore, the higher the engine speed, the less time is allowed for coil charge-up between spark firings for all inductive ignition systems.

Notice that is an inductive ignition, being CDI or capacitive ignition significantly helps the problem. Since the capacitor can charge the coil much faster.

The article goes on the mention the importance of matching your coil to the CDI, is the ATP really matched to the stock coil? I don't have first hand experience with a MSD on a stock coil on a jet ski, but I do on a car.

The MR2 stock ignition system will survive at 500whp (barely) the MSD coil (without a CDI box) will barely make 450whp, the MSD CDI driving the stock Toyota coil will barely make 450whp too, but the MSD CDI + MSD coil was good to over 700whp.

Aaron

 

[QJS]

From Hod Rod magazine:
The article goes on the mention the importance of matching your coil to the CDI, is the ATP really matched to the stock coil?
Aaron

Both the OEM and ATP ignitions are capacitive discharge types. This means that, unlike a coil discharge ignition, no energy is stored in the spark coil. Instead a capacitor inside the ignition box is charged up with sufficient voltage (and so energy) and then discharged into the spark coil at the appropriate time. As the CDI capacitor is discharged the resulting current pulse in the spark coil primary winding generates the spark voltage (10-20KV) in the secondary winding.

Since the ATP ignition uses capacitive discharge, there is no coil 'dwell time'. The time taken to charge the capacitor within the ATP ignition has been designed and tested for engine speeds up to 8000 rpm with wasted spark. This results in a designed capacitor charge time of 3.5 milliseconds. The time taken to for the capacitor to discharge is around 100-200 micro seconds using the OEM spark coil.

Spark energy has been set to a level which is well above that required for good ignition. Similar levels of spark energy are used on MotoGP two stroke engines producing in excess of 400 bhp per litre. Very high power two stroke engines such as these normally have an ignition channel per cylinder. This is because there is a performance gain to be had by having individual cylinder ignition mapping. This is especially true of V twins with asymmetrical exhaust and inlet tracts

So yes the ATP Ignition is optimised for the OEM ignition coil.
Also during our recent tests for our new programmable CDI, we did discover a significant drop in the voltage from the OEM stator at higher RPM but a total loss does not rely on the OEM stator as you already know.
Chris.

 

[easyrhino]

I maybe a 180 degrees out:
The ignition system will only produce enough energy to jump the spark gap. Once the voltage is reached to jump the gap it shorts out. Some spark plugs have an internal spark gap to create a bigger gap for the ignition to jump. Thus causing the ignition system to produce more energy and a hotter spark. IMO the stock single coil configuration will produce a hotter spark than a two-channel system without plugs without internal gaps.

As for ignition charge time (or component raise time), a two cylinder 2-stroke is about the same a V-8 that shares the single–channel ignition system.

 

[Waternut]

There is a lot of talk on here about wasted spark energy and coil efficiency and all that crap. Sure 50k volts sounds so much better than 10k-20k volts but can anyone on here honestly say that they can feel a difference between a stock coil and an aftermarket coil? I know I can't... Heck the guy I bought my first total loss system from said he couldn't tell a lick of difference between a single channel and a multi-channel system.

Higher spark energy should produce a cleaner burn but at the same time, a cleaner burn should produce some kind of performance or fuel economy difference. I've even tried the nice plug wires and a good coil in a car with no difference in either seat of the pants feel or fuel economy.