Whats going on?
Whats going on?
(OP)
I built this gasket for a Moto Guzzi as a test bed to see if an embedded igniter with four paired electrodes would work as a perimeter ignition.
I knew that I would have a timing problem but I am back firing through the exhaust at on/off throttle. The Lambda numbers are ~19. I took 3 of the plugs off line and I am just firing one of the embedded igniter's, and it still is backfiring at on/off throttle with a Lambda of ~16. I took the same plug wire and put it back to the original plug and all is well, with a Lambda of 14.
I will deal with the timing problem later, now I would just like to get one electrode working
I knew that I would have a timing problem but I am back firing through the exhaust at on/off throttle. The Lambda numbers are ~19. I took 3 of the plugs off line and I am just firing one of the embedded igniter's, and it still is backfiring at on/off throttle with a Lambda of ~16. I took the same plug wire and put it back to the original plug and all is well, with a Lambda of 14.
I will deal with the timing problem later, now I would just like to get one electrode working
I don't know anything but the people that do.





RE: Whats going on?
RE: Whats going on?
Finally, how are you driving the electrodes. I could imagine a coil/magneto designed for a single spark plug could get a bit overwhelmed when driving four spark gaps. Weak spark could explain misfire at WOT/max. cylinder pressure...
RE: Whats going on?
I have a 4 prong coil that is 3.75 ohms the stock one was 3.50 ohms.
I don't think there is a problem with it firing as it will go to red line running on one cylinder on one electrode.
Although it will not idle on that cylinder
I don't know anything but the people that do.
RE: Whats going on?
I don't know anything but the people that do.
RE: Whats going on?
RE: Whats going on?
Mike Halloran
Pembroke Pines, FL, USA
RE: Whats going on?
With .040 clearance to the head we feel that any errant spark will soon carbon over and go back to the nice clean tantalum. The gasket thickness is .120" and the tantalum wire is .040" The old gasket was .047" and we took that difference from the head and cc'd the head to regain the volume and resultant compression ratio.
Although the squish has changed it has not shown to be a problem yet and will probably rear its ugly head when it is running well enough to get it back on the dyno
I don't know anything but the people that do.
RE: Whats going on?
RE: Whats going on?
Um. This still isn't clear to me, sorry for being obtuse...but, each spark gap should have its own coil (at least in my perfect whirled), is that your setup?
RE: Whats going on?
It wont idle on that one and will back fire if I open and close the throttle quickly.
My Lambda readings say that I am creating a lean condition but why/how would that be by changing the spark location.
I don't know anything but the people that do.
RE: Whats going on?
That might help your idle popping.
RE: Whats going on?
Your lambda reading is pretty easy to explain - it's reading misfires or partial fires. As the burn is incomplete, air and fuel passes through the engine and the sensor sees the O2 giving a false lean reading. This is consistent with the popping and spitting I think.
The popping spitting/reluctance to run at low speed all read like very retarded ignition (or very lean mix). My suspicion (and this has already been mentioned above) is that the charge density at the edges of the chamber where the spark is, is not sufficient to light/propagate the flamefront easily or is much less turbulent than the rest of the chamber, which all leads towards very slow combustion (when any occurs at all) giving the illusion of retarded timing.
It occurs to me that when the designers first laid out the combustion chamber they will have planned for squish to push whatever is in the chamber towards the spark plug and the spark plug is probably fairly central. This unfortunately means that the engine has actually been designed to shift the charge away from where you are trying to light it?
You could try advancing the ignition (alot) at idle and partial throttle (why not use something like Megajolt or megasquirt n spark to give you a mappable ignition you can play with?). However I'm not sure this will help that much. What I wonder is whether it is worth running all 5 ignition points simultaneously. At idle the original plug does most of the work and then when the engine is working hard and charge densities and turbulence are much higher, the other ignition points can contribute and presumably speed up combustion and make it more complete. This might allow later timing without torque loss and possibly allow higher CR without pinking? Might also be advantageous to vary the timing of the original plug and spark ring independently, but that is getting way over the head of a bush mechanic like me......
I shall watch this with interest
Regards
Nick
RE: Whats going on?
The perimeter of a hemi-head is usually a squish-band. If my understanding of what has been attempted is correct, it will be attempting ignition in the squish-bands.
The above explanation of what your wide-band is doing, is correct. It's a false lean indication caused by mis-fires.
RE: Whats going on?
Interesting idea, by the way ... I suspect the real problem is that the shape of the combustion chamber isn't matched to where you are lighting the fire.
RE: Whats going on?
I never considered running the spark plug as I am putting a 230 bar pressure sensor there.
I think you guys might have hit on something here as I now have the Quadra plug in the cold zone I may grind that out to make sure I induce some swirl in next to those electrodes.
I am working from a patent US7299785 and yes a nine year old orangutan can get a patent LOL
I don't know anything but the people that do.
RE: Whats going on?
RE: Whats going on?
RE: Whats going on?
Brian ....Although I am not doing this for the test the original idea is to have a circuit that is switching power supply. This is a totally independent circuit and will not see the engine components as ground. There are a lot of things to sort out yet, going from wishful dialog to reality.
I will repost when we get more done.
I don't know anything but the people that do.
RE: Whats going on?
i too will be watching this one..
RE: Whats going on?
just my .02 of observation.
J