Ignition Polarity

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tornitore45
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Joined: Tue Apr 18, 2006 12:24 am
Location: USA Texas, Austin

Ignition Polarity

Post by tornitore45 » Sat Jan 31, 2015 9:48 pm

Assuming there is a choice, is there any experimental evidence that a positive spark is better or worst than a negative one?
Mauro Gaetano
in Austin TX

golfpin

Re: Ignition Polarity

Post by golfpin » Sun Feb 01, 2015 6:09 pm

can,t comment on new computer stuff but on the old "kettring" set up eg coil points and condensor definite hard starting if the polarity on the coil was reversed.
Hope this helps.
GOLFPIN.

redneckalbertan
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Location: South Central Alberta

Re: Ignition Polarity

Post by redneckalbertan » Sun Feb 01, 2015 9:04 pm

Golfpin, do you, or anyone else for that matter, know why polarity makes a difference in ignition ability?

dly31
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Location: Northeast Alabama

Re: Ignition Polarity

Post by dly31 » Sun Feb 01, 2015 10:03 pm

I think polarity has something to do with the ionizing of the fuel mixture but am not sure. Of course, some engines operate with two plugs per coil, where both polarities are used.
Don Young

golfpin

Re: Ignition Polarity

Post by golfpin » Mon Feb 02, 2015 12:50 am

Good morning all and thanks again to all who have replied.
Red. I am ashamed that I can,t give you a proper scientific answer but the reply by DL31 is part of it.
If I remember correctly the spark at the plug is reversed, cannot remember which way, it moves from engine [ground perhaps] with plug becoming the positive? The old test was to interpose a graphite pencil between a plug wire and ground and see which side of the pencil the spark occurred, I cannot remember but I have a funny feeling it was not what I expected! Have just looked up "The Sports Car Engine" page 42 by Colin Campbell but this was written in 1963 !!!!! I think the principals are much the same and as I said DL31 I think has got right on, it has to do with the ions in the fuel mixture that are both neg and pos then there is a tie up with the problems associated with incorrect polarity causing amongst others but certainly hard starting is one.
Hope that helps. Campbell,s treatise does not explain which way the spark moved, engine to plug or vice versa.
Golfpin

golfpin

Re: Ignition Polarity

Post by golfpin » Mon Feb 02, 2015 12:53 am

Sorry got the name wrong, that last E should have been addressed to Mario.
Cheers Golfpin

tornitore45
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Joined: Tue Apr 18, 2006 12:24 am
Location: USA Texas, Austin

Re: Ignition Polarity

Post by tornitore45 » Mon Feb 02, 2015 9:29 am

Thanks for the response.
Aside the curiosity the main reasons I asked is I have an S&S CDI ignition module that has a fully floating HV secondary.

I packaged it into a general purpose box with battery, power switch and a switch to select the active trigger edge polarity so that can be used with points or Hall effect sensor.

I have a boxer engine running with a wasted spark system. In other words the plugs are in series, each receive one of the secondary leads. One plug is always pulsed positive and the other always pulsed negative.

I can not perceive any asymmetry in the cylinder firing efficiency but that does not means there could be such.

I am also using the same box for a hit and miss and I have a choice of reversing the plug and frame connections, changing the polarity.

I have not figured a good way to determine the box output polarity. I may try an LED in place of the plug but wander whether the light pulse is long enough to be seen.

Anyway this is an interesting topic.
Mauro Gaetano
in Austin TX

golfpin

Re: Ignition Polarity

Post by golfpin » Mon Feb 02, 2015 2:51 pm

Golfpin here,
you are way ahead of me here in terms of electronic ignitions. All I can add is as I recall due to the pressures exerted by exhaust emission control regs that at sometime manufacturers resorted to a "delayed" ignition event, 2 nd plug to try and create a more complete burn of what was in the combustion chamber, sorry I am on thin ground here, but as one contributor stated the combustion process in scientific terms is not a burn but a rapid "ionisation" of the mixture.
Picking up on Campbells book he refers to the spark phenomena, I don,t have the energy nor do I wish to bore everyone with the contents of his narrative, but I get the feeling that the reversal of polarity in modern day terms, "read emissions" may have some bearing on the matter.
Hope this helps, also am always curious about things I don,t know about. To repeat, my ref source is Colin Campbell "The Sports Car Engine" page 46 if I knew how to I would scan it and send but am an idiot on the PC. Quite sure there are more up to date references.
Cheers Golfpin
Ps have just reread your post I wonder if you put an exhaust analyser onto you setup if any thing would reflect given that you have switching facility; the last time I had anything to do with that sort of tech is about 15 years ago. The analysers [Sun machine] were able to give amazing breakdowns of what was happening in the exhaust as a result of the combustion process? I am guessing.

tornitore45
Posts: 1439
Joined: Tue Apr 18, 2006 12:24 am
Location: USA Texas, Austin

Re: Ignition Polarity

Post by tornitore45 » Mon Feb 02, 2015 3:37 pm

Exhaust gas analysis is way beyond my capabilities, after all I am working on model engines.
I will, however, do a search on the internet since it appears that this subject has been addressed in the industry.
Mauro Gaetano
in Austin TX

golfpin

Re: Ignition Polarity

Post by golfpin » Tue Feb 03, 2015 1:00 am

Morning Mauro,
Thanks for the update but I did not realise you were working on model engines, sounds fascinating.
Cheers Golfpin

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ken572
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Re: Ignition Polarity

Post by ken572 » Tue Feb 03, 2015 8:01 pm

(ALL) :D

Your answer is here: 8)

Click on the link, and when you have arrived,
SCROLL DOWN to the article.

http://firetrucksandequipment.tpub.com/ ... -1_545.htm

Ken. :)
One must remember.
The best learning experiences come
from working with the older Masters.
Ken.

redneckalbertan
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Joined: Thu Nov 01, 2012 10:39 am
Location: South Central Alberta

Re: Ignition Polarity

Post by redneckalbertan » Tue Feb 03, 2015 8:12 pm

Thanks Ken!

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