Ignition Optimization products?

[Osm3um]

Years ago I ordered a Jacobs ignition system for my air cooled volkswagen. It measured the resistance across the spark plug gap and automatically adjusted the spark based in the proper ignition. It had a computer module and a variable coil. They have been bought but still sell some stuff for cars under the name accel ignition systems.

 

End result was a smoother idle, drive, 25% increase in mpg and a 33% decrease in emmissions (as measured by the state). Granted it was an old dual carb, air cooled volkswagen, but the difference was impressive.

 

Is there anything like this for BMW bikes? I see there is the "power commander" but I am not interested in lowering my mpg.

 

Thanks,

Bob

[Woodie]

Interesting product!

 

I've never heard of anything like that for FI, except for Power Commanders/Techlusions, which are really fuel mapping tools, not spark management things.

 

[T__]

Bob, something fishy with that Jacobs system.. How could it measure the resistance across the spark plug electrode gap? Try it with an ohm meter & you will find an AIR GAP has infinite resistance (air gap = nothing to measure)..

 

“25% increase in mpg and a 33% decrease in emissions (as measured by the state)”.. Now that is IMPRESSIVE.. And to think the Motor Companies spend millions & millions to get under one percent improvement.. I wonder what State did it? Then again I wonder why “the State” would be messing with something like that anyways..

 

Save your money & get a fuel controller as the Spark on the BMW is already computer controlled & very stout.. If set up correctly a fuel controller doesn’t have to lower your fuel economy very much..

 

Now if you want to spend the money & get your cylinder heads set up to use dual spark plugs then you would see an improvement in engine operation (not cheap but effective)..

 

Twisty

 

[David R]

Bob, something fishy with that Jacobs system.. How could it measure the resistance across the spark plug electrode gap? Try it with an ohm meter & you will find an AIR GAP has infinite resistance (air gap = nothing to measure)..

 

Snip....

 

Twisty

 

The system could measure the current draw and voltage it takes the primary side of the coil to fire the plug. Compute from there....

 

25% eh?

 

[ShovelStrokeEd]

Not much point in that modification these days.

 

The BMW already comes with a computer controlled system with a very powerful output coil. Timing, the most important component, is very carefully controlled and optimized for minimum emissions and good power delivery. I very much doubt any of the aftermarket stuff could provide an improvement over the OEM system. Especially in light of the hours/deutchmarks/Euros spent on dyno development.

 

I have run most of the after market systems available for bikes in race applications where combustion chamber pressures are ridiculously high. I'm talking 15:1 compression ratios and a healthy dose of nitrous oxide to boot. There, the extra spark strenght has some benefit but honestly, I couldn't tell much difference in performance between MSD, Dyna or Accel. I have also run magneto ignition on a couple of fuel (nitromethane) bikes. Being these were racing applications where the motor spent all its time either idling at about 3K RPM or wide open and running through the gears, we just static timed them, no ignition curve at all except for some high RPM retard to keep the motor out of detonation.

 

Best mod you can make to your ignition system is to maybe open up the plug gap a bit for a fatter spark. The coil can handle it as can the trigger mechanism. You'll have to change plugs a bit more often but it should get you at least some of what you seek.

[Osm3um]

Bob, something fishy with that Jacobs system..

 

It's the real deal, still have it somewhere. It's primary market was for older air cooled VWs (as far as I know).

 

Jacobs has a doctorate in physics or something and wrote a book, that the resistance can be measured across a gap but the resistance changes when the ignition occurs. Depending on the resistance the spark is dynamically increased. Even more interesting, after the ignition, it reversed the polarity of the spark thus keeping the plugs clean and making them last longer.

 

Remember, the van I had was a 1973 VW camper, air cooled 1700cc. The ignition system was about as basic as they come and old (already had replaced the points with an optical system). Pretty much ANY system would probably have improved the efficiency of the small engine pushing a giant toaster shaped vehicle.

 

As I recall I was getting about 15 mpg before and about 19 mpg after. As for the emissions, I did not pass the emissions in our state, bought the Jacobs unit and passed with flying colors. the emissions numbers were about 33% better. The plugs lasted forever after the Jacob's was installed and never fouled.

 

I started thinking about it when I saw the "power commander" injection mapper.

 

Bob

 

PS I will see if I can find the book and can copy a few pages if anyone is interested. Pretty interesting read.

 

PSS There is a quite a bit on the web, search for jacobs ignition. Also, check this out: Book

[T__]

Bob, Ok,, then buy one & install it.. Tell us how it works..

Just remember that both cylinders on your BMW spark at the same time & once each time the piston comes to TDC (even on the exhaust stroke).. It uses a lost spark system.. One side sparks positive polarity (& the other side sparks negative polarity..

 

Make sure it won’t burn the coil driver transistor out in your fueling computer or it will get very expensive..

 

25% better fuel economy eh! Go for it!

 

 

Twisty

 

[11101110]

Bob, something fishy with that Jacobs system.. How could it measure the resistance across the spark plug electrode gap? Try it with an ohm meter & you will find an AIR GAP has infinite resistance (air gap = nothing to measure)..

 

I have to disagree. I could meausre that. with a piece of equipment at work. We are also looking at getting another piece that will measure even higher resistances. I'm talking 10 to the 15 ohms here.

 

But remember once the voltage ionizes the air gap the resistance goes waaaaaaaaaaaaaaaaaay down.

 

Wow one spark the electrode is positive and the other is negative. That means with respect to the ingition module the engine and bike are floating. that is strange.

[David R]

Most cars with coil packs run 1/2 + spark and 1/2-. They must use both ends of the coil. They have three packs of two.

 

Just as a guide, it takes 10 to 40 thousand volts to initiate the spark and maybe 2kv to 6kv to keep it there. I can show you a picture on a scope if you would like.

 

I don't understand why the plug gap is only .035". Most car engines that run lean (meet federal emissions) use .045 to.060" gap and up to .080". I set the gap .035" for my /6 with points. Its at .035 on my R1100RT too because I don't want to burn anything up with a bigger gap.

 

David

[Osm3um]

Bob, Ok,, then buy one & install it..

 

Sorry, I certainly didn't mean to imply I am anything more than a neophyte, but I thought it was an interesting product (15 years ago).

 

Drive safe,

Bob

 

 

[T__]

11101110, I can’t imagine any piece of equipment that could get a meaningful measurement of the resistance of a spark plug electrode gap.. That gap resistance would be so temperature & humidity dependent how could you ever get repeatable measurements? Must be some machine?

 

On the spark plug polarity.. Yes the engine block is just part of the ground path not a finite ground (low)..

 

On the ign coil, instead of one end of the coil secondary winding going to a sparkplug & the other to chassis ground (back through the primary ground path) as most do.. On the BMW (pre hexhead & one set of plugs on the dual plug oilhead) one end of the secondary goes to one spark plug & the other end of the secondary goes to the other spark plug.. That allows ONE ign coil to spark 2 spark plugs (one + & one -).. Otherwise it would take 2 separate ign coils & 2 separate HES sensors as both pistons are at TDC at the same time but one is on compression & the other on exhaust.. A lot of automobiles use the lost spark type ignition to allow 2 spark plugs on one ign coil.. As long as cam overlap allows nothing but exhaust in the combustion chamber at lost spark time no harm no foul..

 

Twisty

 

[T__]

clip~

 

I don't understand why the plug gap is only .035". Most car engines that run lean (meet federal emissions) use .045 to.060" gap and up to .080". I set the gap .035" for my /6 with points. Its at .035 on my R1100RT too because I don't want to burn anything up with a bigger gap.

 

David

 

 

 

David, more than likely the coil can handle a little more plug electrode gap.. Not a lot but a little more.. It usually has more to do with spark plug wire insulation (the large plug gap systems use thick silicone type ign wires) & coil internal insulation & coil type.. Some of the higher KV systems also use longer porcelain length spark plugs so the plugs don’t carbon track down the porcelains in damp weather..

 

In fact a lot of systems now don’t use any plug wires at all as they have COP type systems or stick coils..

 

Problem with opening the plug gap on a conventional system is the spark leaking to ground though wires & coil insulation & enough coil output.. But also spark duration.. If you only have say 40K available you can use a wider plug gap & get a higher KV spark for a shorter duration or use a smaller plug electrode gap & get a lower KV spark for a longer duration.. You only have X amount available how do you want to use it?

 

Twisty

 

[11101110]

I have only recently been measuring resistances well into the teraohm range and the meter I use could even measure the resistance of the ceramic insulator on the spark plug. However I have a lot of experience measuring picoamps. At extream ranges it really becomes a pain in the a$$. The human body produces sufficient interference, both internally and via static charge, to screw up readings.