Ignition voltage in a waste spark system.

Click For Summary

Discussion Overview

The discussion revolves around the ignition voltage required to initiate a spark in a waste spark ignition system, specifically in the context of an old 2-cylinder Citroën 2CV. Participants explore the factors influencing ignition voltage, the behavior of dual output ignition coils, and the relationship between the two spark plugs in the system.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant notes that the ignition voltage depends on various factors, including the dielectric in the plug gap and the pressure in the combustion chamber.
  • Another participant questions whether the two outputs from the dual ignition coil are independent and suggests checking the resistance between the high-tension leads.
  • A participant describes the dual output ignition coil as having reversed polarity outputs and a transformer ratio of approximately 1:100, indicating both high-voltage sections are connected in series.
  • It is proposed that both spark plugs must fire together since they are in series, which may explain the ability to achieve sufficient voltage for both plugs despite differing conditions.
  • One participant expresses confusion about the necessity of both plugs firing for one to spark, suggesting that the current may only be present in the ionized gap of the spark plug and not in the cables.
  • Another participant argues that there must be current flowing through the spark plug gap for a spark to occur, challenging the idea that no current exists in the spark cables during sparking.
  • A participant describes an experiment using a graphite pencil to test spark polarity, noting differences in spark appearance based on polarity.
  • There is a discussion about the nature of the spark and the conditions under which it occurs, with some participants suggesting that the spark can ignite fuel regardless of polarity.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of the ignition system, particularly regarding the independence of the spark plugs and the nature of current flow in the system. The discussion remains unresolved, with multiple competing perspectives on the mechanics of the waste spark system.

Contextual Notes

Participants acknowledge the complexity of the ignition system and the various factors that influence spark generation, including dielectric conditions and the behavior of the ignition coil. There are references to specific measurements and experiments that may not be universally applicable.

  • #31
.
Vk6kro, Sophiecentaur and Bob_S

I really thank you for advising me so wisely on this matter.

Obviously, something is wrong in my test and the only place I cannot verify the "lost spark" is inside the coil.

I do not know why, but I discarded that possibility, as I know of several 2CV drivers who because of a failure in plug or any other part in that branch, drove hundreds of kilometers without damaging (or some?) the ignition coil.

For that, I am with your opinion, but I was really confused for the matter I mentioned.

Thanks a lot you all
 
Last edited:
Engineering news on Phys.org
  • #32
CHICAGO said:
.
Vk6kro, Sophiecentaur and Bob_S
I do not know why, but I discarded that possibility, as I know of several 2CV drivers who because of a failure in plug or any other part in that branch, drove hundreds of kilometers without damaging (or some?) the ignition coil.

A 301cc single cylinder engine! Wow.
2CVs just go on and on. You just need to re-weld bits now and again - and again - and again!
Probably the most stylish car that ever there was.
 
  • #33
sophiecentaur said:
A 301cc single cylinder engine! Wow.
2CVs just go on and on. You just need to re-weld bits now and again - and again - and again!
Probably the most stylish car that ever there was.
A 2CV is a "deux chevaux" only if both horses are pulling; otherwise it is an un chevaux.

Bob S
 
  • #34
Bob S,
reckon it would be more like a broken down nag, because of pumping losses in that dead cylinder.

Happened on this one a bit late, but I'm wondering if CHICAGO ever did post his findings on a 2CV-related forum?

Ken.

< http://www.flickr.com/photos/30132857@N06/3654939718/ >

( Still trying to work out how anyone could be so lacking in sympathy for the machinery that they'd plod on for hundreds of kilometres with the engine turning out less than 50% of its rated 28 bhp. )




Bob S said:
A 2CV is a "deux chevaux" only if both horses are pulling; otherwise it is an un chevaux.

Bob S
 
  • #35
I might suggest that one would not notice the difference between 'under-powered' and 'seriously under-powered'. I had one for several years and lack of power never surprised me. You just never compete with anyone else on the road (except, perhaps ageing lady cyclists).
And we can do without hurtful references to "nags", thank you. You may need to have owned one to appreciate just how nice they are. I could 'take' a Ferrari on a road with speed bumps, any day!
 
  • #36
sophiecentaur,
I fear you have misunderstood me, as I've driven nothing except these little cars since 1979 and have made my living out of working on them since 1994, including selling UK manufactured components for them to customers in France.

That's what we refer to as 'Coals to Newcastle'.

If you'd looked at some of the other photographs on my Flickr pages, you'd probably have realized that I'm beyond help as far as A series Citroens are concerned... ;o)

Ken
sophiecentaur said:
I might suggest that one would not notice the difference between 'under-powered' and 'seriously under-powered'. I had one for several years and lack of power never surprised me. You just never compete with anyone else on the road (except, perhaps ageing lady cyclists).
And we can do without hurtful references to "nags", thank you. You may need to have owned one to appreciate just how nice they are. I could 'take' a Ferrari on a road with speed bumps, any day!
 
  • #37
Also. Alles ist klaar.
 

Similar threads

Replies
2
Views
839
Replies
7
Views
4K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 17 ·
Replies
17
Views
4K
  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
Replies
2
Views
3K
  • · Replies 17 ·
Replies
17
Views
9K
  • · Replies 2 ·
Replies
2
Views
4K
Replies
14
Views
5K