Plasma Ignition

Originally posted by geek National Instruments was selling a flavor of Labview for the Palms.  There were a few with USB.  I looked into it but they wanted a whole new license for the software.  Cost would have been more than buying a top of the line logger.  You may be able to just code it in C# or C.  I am not sure what they want for the Palm development tools anymore.  I'm not a USB fan.  I met one of the members who worked on that standard.  Unimpressed to say the least.   I have worked for two companies that tried to use it for products and abandoned their efforts.   The basic problem is there is no common mode rejection.   The devices are DC coupled.   The chipsets are not designed to handle any sort of EMI.   The engineer I spoke with felt that with the two units being DC coupled by the cable, there could be no potential between the two.   He had no concept of RF.   So, you want to use plug wires that know are going to create a lot of splatter but you want to run USB too.  It's an oxymoron.   My advice is to use shielded cables, buy stock in a ferrite company then test the crap out of it before you head to the track!!   You have your ignition on the bench, so this will be a great way to see how things hold up. The other thing you may want to consider and test the crap out of is the MC4's trigger input.  It has been my experience that the trigger input can be very prone to noise pickup.  Once it gets lost, it takes some number of pulses to recover as  the bike tries to buck you off.     Sorry if I'm coming across a bit negative.  Just trying to give you a heads up and maybe save you some time.

You aren't negative Good point. This plasma-booster will probably cause large EMI. Probably we will have to build separete grounded aluminium boxes for different electronics.

I am guessing they may do more harm than good.   With the tests I have ran, it seems that the ignition is not the worst part, its getting the energy transferred into the plug.   Wires and boots appear to be the weak link.  Having any metal near the high voltage wire just seems like a bad idea.  

Would be fun to put a set next to the ones I have looked it just to see. 

Picture showing my grill starter, target (proto 1 & 2), WB current transformer, large shunt and basic 4-wire sense.    Small gold box contains very high freq. transient protection for the scope.   Flash tube would be way to slow to save it.

Our purpose was not to test nology-wires, but because we have those wires we could also test those. Probably those wires are good for testing testbed.

Good luck trying to get anything working at 500PSI air pressure.   I would like to see some videos when you get to this point.   Or, maybe you can set the air gap to something small enough.   Post all the details when you do it.


Yes, these are common devices used to look at current.   

Originally posted by shmot That bike is only for fun  A "streetbike" with 10 lb billet headlamp and methanol.   Also somebody else will have to ride it. I just want to build it for 40-year birthday-present for myself

Plasma threshold voltage at 0 psi and 100 psi (voltage before diode, 77.4 V/div):
0 psi


100 psi


It seems that spark threshold voltage will drop at beginning of spark when boost increases. Interesting.


Edited by shmot - 27 October 2009 at 1:46am

Originally posted by geek Video looked good.  Were your trying to kill the poor guy with the exhaust?  Looks like he found a new place to sit pretty fast.

Methanol is not very healthy. It is better not to sit nearby exthaust

Originally posted by geek Scope seems to be working good.   Not a bad looking interface.

Sometimes software does get stuck. Then I need to take usb-wire off and on. Probably some EMI-problems. Like you said.

In the previous pictures constant voltage is 305 V. With 0 psi voltage drops to 92 V and after 37 us drops to 82 V. Diode threshold voltage is 34 V. Then spark treshold voltage is 58 V at beginning of spark boost and 48 V at the end of the spark boost.  With 100 psi voltage drops to 45 V and after 32 us increases to 92 V. Then spark treshold voltage is 11 V at beginning of the spark boost and 58 V at the end of the spark boost. Treshold voltage drop at the beginning of 100 psi spark boost is probably caused because when pressure increases needed spark voltage increases and there will be increased current spike at the beginning. Our theory is that increased current will reduce plasma threshold voltage. But with 0 psi threshold voltage decreases when current decreases. Strange.

... This is where and when you two passed me. I did not learn anything significant about ignition since.  So it's '62 and I am under the hood of my '55 Ford, with a long Millers Falls screw-driver, that is attached to number one plug wire, (the wire is not attached to the plug), holding the screw-driver down near the timing mark I am able to arc it over to the mark and or the dampener and get an accurate timing setting. It's a good thing it was not a digital -Seven. It probably would have killed me. Did not have a timing light. The old necessity thing.

I read the Song Lee paper you sent.  

Combustion, Explosion, and Shock Waves, Vol. 39, No. 5, pp. 513-524, 2003
Experimental Study of Ignition of a Gasoline-Air Mixture in a Constant-Volume Combustion Chamber
http://encod.hanyang.ac.kr/Paper_kihyung/CVCC%20Ignition%20System.pdf

There are a few things that I noted. 

In section 2.1, they are talking about the breakdown phase being in the 200Amp range in the 1-10nSec.    Now, you may not be interested in this information but again, if the front end of the scope saturates, the recovery times can be in the several mS range.  Making your data totally corrupt.    So, again, just be aware of it.   I find it a bit strange that in many of these papers (All) that I have read, none mention this.  It would be funny if all these university and IEEE papers were wack because the people running the tests did not understand how a scope works.       

I know I have posted it before but looking at this data is just not that simple.  

While they do inject a known mix, they do it at 0 pressure.    Section 2.2,  page 517 they do talk about the problems with a lean charge, which makes sense that this would drive the research. 

Notice on this same page, they state: "If the current increases above 200mA in the glow-discharge phase, the transition to the arc phase occurs, which severely melts the electrodes."     Now this is the testing I want to do!!! 

In the end, they never tie any of this back to real world data.  My point is that for a race engine, I doubt many will care about fuel economy or emissions.    This is where most of this research is coming from.   They have shown how changing their setup effects the flame speed, but they have no reason to tie this into power or E/Ts.      

What I would like to see is data taken off a dyno.  If the flame speed changes and advances the timing, normalize the data for it.  In the end, is there any gains to be had that relate to this sport?    

It's still an interesting topic.   







Edited by geek - 27 October 2009 at 10:19pm