Spark Plugs

[yendor]

Ok let me start the ball rolling by placing this hypothesis on the table.

A lower spark ionisation voltage allows the spark plug a larger aperture for the spark to jump across and the resultant spark is more intense due the larger amount of energy available to perform ionisation.

This has the effect of advancing ignition by fractions of a degree and up to a degree max at max RPM. In addition to this small benefit, a low ionisation voltage intense spark gives "accurate" burn timings.

The definition of "accurate" is what i define in the following steps
1. ECU generates command to ignite based on values of its map. (assume as reference in this case)
2. ECU output transistors amplify signal to generate a square pulse. ( slew rates of analog amplifiers apply)
3. Signal propagates along wires to the ignition amplifiers. ( propagation along wires taken as negligible as it is constant for all systems)
4. Ignition amplifiers act on the pulses and on the positive edge to commence charging of coil and on the negative slope cut off the current and the coil generates the spark. ( slew rates of amplifiers apply, Output of the coil is proportional to the rate of decrease of the current. V = L x dI/dT. In english is the output voltage is equal to the inductance of the coil multiplied by the rate of current change. The result of this is a voltage that increases with time and requires a finite time to reach maximum voltage)
5. The energy travels along HT cables or conductors. (propagation also is a constant. Distributor systems are not included)
6. Energy builds up across the tips of the spark plug and any voltage above the instaneous ionisation voltage results in a spark whereby the energy of the coil that is greater than the ionisation level goes into the intensity of the spark.

To be "accurate" I want the shortest possible time lag and the strongest spark to fire all kinds of mixtures.

In terms of mixtures, I will go so far as to say that the mixture in the entire combustion chamber is not homogenous and that there are leaner areas and richer areas. This will change the dielectric (insulating) properties of the spark gap and thus raising or lowering the ionisation voltage. Lean mixtures have higher dielectric value and thus higher voltage required to allow sparking and converse for richer mixtures.

If we hold the gap and construction of plug constant, the ionisaton voltage will only depend on the instaneous insulating properties of the mixture. If you narrow the gap, the flame front is smaller and cyl pressures are not fully optimised. If the gap is increased, spark area is large but intensity is weaker, also sub-optimal operation.

To raise the ionisation voltage of materials, they are made round and free of points. This will spread the electrical charge over the entire area. ( witness the insulators of HT electrical transmission lines and you will see nice curvy ceramic insulators. The static electricity generator has a sphere on the top for the same reason.)

Thus using this property, spark plug manufacturers produce smaller tips to reduce the ionisation voltage. The challenge all along was to find a material that can withstand the intense heat of sparking ( not combustion temp) without evaporation or transfer of electrode material and the welding of such metals. Of course must be done at cheap commercial rates. The whole exercise is to produce sharp points. (iridium/platinium electrodes, ND U grove, Split Fire V grove...)

So a lower ionisation voltage allows the spark to happen earlier and fire through a greater range of mixtures moving around the chamber with greater intensity.

I have deliberately removed all traces of values to limit this to a discussion on concepts.

Quantitative values may come later when dyno figurers come.

Lets discuss about this concept.

Opinions?

Cheers

Rodney

 

[TripleM]

Re: Spark Plugs

Actually my take is this...
Dyno will cost 60bux to do each run so before and after will be 120bux ( hope I m rite )

The 6 plugs for the M54 engine cost 135 bux so if one wants to do dyno for this mods, the costs will be 255 bux in total which in my opinion is absolutely waste of time and money.

A better throttle response and better butt feel in pulling power, stable idling and the factory warranty are more than enough.

It's pointless to debate over such small mods that would require dyno to prove...

That's just my opinion. Hit me back, anybody..

Nonetheless, I am goin to get em too.

Cheers and happy modding

 

[Shaun]

Re: Spark Plugs

This has the effect of advancing ignition by fractions of a degree and up to a degree max at max RPM.

The numbers show that 1 degree is more typical of a 9500 RPM engine. For a standard 6500 RPM redline engine, it is closer to 0.7 degree.

To be "accurate" I want the shortest possible time lag and the strongest spark to fire all kinds of mixtures.

Agree. But would like to add that if the time lag is known, it also can be compensated for by the control system. If for example you are searching for best torque on a dyno, and you're shifting ignition point around, it doesn't matter what the value is shown on the screen. The actual degree where the spark is fired is exactly what is yielding best torque. When the stock car was getting mapped, I'm sure the engineers took into account the lag and not by programming with just a fixed value.

In terms of mixtures, I will go so far as to say that the mixture in the entire combustion chamber is not homogenous and that there are leaner areas and richer areas. This will cause the dielectric (insulating) properties of the spark gap and thus raising or lowering the ionisation voltage. Lean mixtures have higher dielectric value and thus higher voltage required to allow sparking and converse for richer mixtures.

If we hold the gap and construction of plug constant, the ionisaton voltage will only depend on the instaneous insulating properties of the mixture. If you narrow the gap, the flame front is smaller and cyl pressures are not fully optimised. If the gap is increased, spark area is large but intensity is weaker, also sub-optimal operation.

To raise the ionisation voltage of materials, they are made round and free of points. This will spread the electrical charge over the entire area. ( witness the insulators of HT electrical transmission lines and you will see nice curvy ceramic insulators. The static electricity generator has a sphere on the top for the same reason.)

Thus using this property, spark plug manufacturers produce smaller tips to reduce the ionisation voltage. The challenge all along was to find a material that can withstand the intense heat of sparking ( not combustion temp) without evaporation or transfer of electrode material and the welding of such metals. Of course must be done at cheap commercial rates. The whole exercise is to produce sharp points. (iridium/platinium electrodes, ND U grove, Split Fire V grove...)

So a lower ionisation voltage allows the spark to happen earlier and fire through a greater range of mixtures moving around the chamber with greater intensity.

No contention here. What I have been saying all along however, is that a properly functioning standard plug already has been designed to fire sufficiently in whatever AF it may encounter in the chamber. It is not as if that there is going to be a sudden swath of super lean mixture is going to delay ignition or cut it short. The manufacturers have tested this and have advanced misfire detection whether by on board torque measurement or real time exhaust gas analysis on a rig. If they had found a sparkplug that could for a few dollars, give them a no-wear (efficiency gain) 5-10hp, and go 160,000km, they would be overjoyed. Consistent burn and no misfires also would mean hugely improved emissions.

Regarding running our own tests where gains are on the small side and can easily enough be swallowed up by variance - I tend to take with a huge handful of salt, any result where coolant, fuel, and oil (including gearbox oil) temps, are not logged, tire pressures monitored and equalized between runs, ECU trim values logged, or where the baseline run not on a healthy car. When the variance in the dyno itself can be a couple of hp, things get really tricky. On big gain things, I care less because variance is a fraction of expected gain. Now on the other hand, the manufacturers have access to near perfectly controlled tests with all fluid temps controlled to +/- 2 deg F, controlled barometric pressure and humidity, yielding repeatability in the 0.07% range with the worst being 0.25%. This means if they were to dyno a 170 hp engine, they would typically record a high of 170.119 hp - and on the very worst of days, a high of 170.425 hp.

So I hope you will forgive me for erring on the skeptical side and perhaps putting too much trust in a quality manufacturer like BMW. I suppose it doesn't take very long or very much money to try out these plugs, but it still is something. It's not so much the money as it is the time. I'm just putting this up for people who potentially don't have much time to spare, or money to spare.

Thanks for starting this thread and taking the time to explain what you mean in such detail. I hope there are no hard feelings.


Best regards
Shaun

 

[Shaun]

Re: Spark Plugs

It's pointless to debate over such small mods that would require dyno to prove...

If it can potentially save someone 135 dollars and an hour or two, then I don't see the harm in discussion. Sometimes the pursuit of knowledge and the weighing of differing views and concepts can be interesting.

 

[kenntona]

Re: Spark Plugs

If it can potentially save someone 135 dollars and an hour or two, then I don't see the harm in discussion.

So the implication is that the spark plugs are a waste of money? Dun get me wrong, your opinion, while incomprehensible many a times, has its weightage. So, if you think it is a waste of time and money, let the forum know. Like how you evaluate the OBIT chip.

 

[Shaun]

Re: Spark Plugs

So the implication is that the spark plugs are a waste of money? Dun get me wrong, your opinion, while incomprehensible many a times, has its weightage. So, if you think it is a waste of time and money, let the forum know. Like how you evaluate the OBIT chip.

The word 'potentially' is key. Wait till the day the possibility is conclusively proven or disproven. That day may never come in the real given standards and equipment enthusiasts have access to, but more importantly that the variance has the potential to be larger than claimed gain.

Neither butt dynos nor large variance dynos and dyno standards qualify as conclusive. No kind of blind test has even been conducted. That is why conclusively determining that small gain mods work or do not, is tough.

Obit was a different matter altogether. That one was very clearly flawed in concept and in reality. In fact, maybe Rodney or Shawn will be kind enough to tell you something about it - that is.. if you desire to comprehend it.

 

[TripleM]

Re: Spark Plugs

It's no harm for discussion but if decision making has to be made all the time using proven numbers and commanded by the majority of consumers, then I am interested in opening a shop specializing in dyno which includes motorcyles, aircraft, submarine and tank...swee2x..

 

[kenntona]

Re: Spark Plugs

Neither butt dynos nor large variance dynos and dyno standards qualify as conclusive. No kind of blind test has even been conducted. That is why conclusively determining that small gain mods work or do not, is tough.

I am learning insofar as my limited technical knowledge and mental capacity could allow for. As such I did not install OBIT in my ride. But in this case, you seemed to suggest that we should not purchase Volker's spark plugs on the claimed product merits? Or would you kindly make a firm comment - should we buy the product on its price and merits? I was keen.

 

[Shaun]

Re: Spark Plugs

I only make negative comments about clearly flawed concepts or logic that are/is plainly erroneous. This sparkplug concept is not flawed. If you read the original spark plug thread, you will read that I do not doubt there is an improvement. How much of a degree is what is up in the air till properly tested.. and that looks a long way off. My personal opinion may be that it yields around 1hp tops, while Rodney's opinion might be that it yields more than 5hp. Given that there is no conclusive test, there is also no gain/dollar gain/time ratios, so I don't have an opinion on whether to buy it or not.

My stand over the past 2 years has consistently been to keep things stock and save money for either a better car or save up enough to go for big gain changes that are not questionable. Perhaps it is because I am a starving student and see a little money as a lot. I also see time as very valuable. Older people raking in the money and having lots of spare time might see things differently and want to try everything under the sun.

So it is hard to say, which is why we stick to discussing what we do know, or explain our logic - leaving individuals to make up their own minds after taking the different factors into consideration.

 

[NTY]

Re: Spark Plugs

No contention here. What I have been saying all along however, is that a properly functioning standard plug already has been designed to fire sufficiently in whatever AF it may encounter in the chamber. It is not as if that there is going to be a sudden swath of super lean mixture is going to delay ignition or cut it short. The manufacturers have tested this and have advanced misfire detection whether by on board torque measurement or real time exhaust gas analysis on a rig. If they had found a sparkplug that could for a few dollars, give them a no-wear (efficiency gain) 5-10hp, and go 160,000km, they would be overjoyed. Consistent burn and no misfires also would mean hugely improved emissions.

Regarding running our own tests where gains are on the small side and can easily enough be swallowed up by variance - I tend to take with a huge handful of salt, any result where coolant, fuel, and oil (including gearbox oil) temps, are not logged, tire pressures monitored and equalized between runs, ECU trim values logged, or where the baseline run not on a healthy car. When the variance in the dyno itself can be a couple of hp, things get really tricky. On big gain things, I care less because variance is a fraction of expected gain. Now on the other hand, the manufacturers have access to near perfectly controlled tests with all fluid temps controlled to +/- 2 deg F, controlled barometric pressure and humidity, yielding repeatability in the 0.07% range with the worst being 0.25%. This means if they were to dyno a 170 hp engine, the furthest they would typically record a high of 170.119 hp - and on the very worst of days, a high of 170.425 hp.

So I hope you will forgive me for erring on the skeptical side and perhaps putting too much trust in a quality manufacturer like BMW. I suppose it doesn't take very long or very much money to try out these plugs, but it still is something. It's not so much the money as it is the time. I'm just putting this up for people who potentially don't have much time to spare, or money to spare.

Thanks for starting this thread and taking the time to explain what you mean in such detail. I hope there are no hard feelings.


Best regards
Shaun

Well said Shaun! This is the best write up I've seen from you. Too bad I learnt my lesson through the hard way. I have several bad experience with aftermarket plugs.

 

[Crufty Dusty]

Re: Spark Plugs

The numbers show that 1 degree is more typical of a 9500 RPM engine. For a standard 6500 RPM redline engine, it is closer to 0.7 degree.

... in English, this means very minimal HP gains.

Agree. But would like to add that if the time lag is known, it also can be compensated for by the control system. If for example you are searching for best torque on a dyno, and you're shifting ignition point around, it doesn't matter what the value is shown on the screen. The actual degree where the spark is fired is exactly what is yielding best torque. When the stock car was getting mapped, I'm sure the engineers took into account the lag and not by programming with just a fixed value.

More precisely, this time lag is so short as to be negligible. In the 50-60 microseconds range. Coils would need time to be energized (ignition dwell time), but these time lags can be programmed based on voltage, as Shaun stated earlier.

 

[Welbo]

Re: Spark Plugs

So the implication is that the spark plugs are a waste of money? Dun get me wrong, your opinion, while incomprehensible many a times, has its weightage. So, if you think it is a waste of time and money, let the forum know. Like how you evaluate the OBIT chip.

Hi Ken,

I got my plugs today and my initial feel from "pure butt" feel is that my car is able to pull smoother to the redline. This is my 3rd set of plugs and is definitely better than my stock plug and the Denson Iridium plug that I changed to 6 mths ago. However, this is based on PURE BUTT FEEL.


Cheers!

 

[yendor]

Re: Spark Plugs

Thanks Welbo

Sorry could not catch up with you at the workshop..

Cheers

Hi Ken,

I got my plugs today and my initial feel from "pure butt" feel is that my car is able to pull smoother to the redline. This is my 3rd set of plugs and is definitely better than my stock plug and the Denson Iridium plug that I changed to 6 mths ago. However, this is based on PURE BUTT FEEL.


Cheers!

 

[yendor]

Re: Spark Plugs

Actually my take is this...
Dyno will cost 60bux to do each run so before and after will be 120bux ( hope I m rite )

The 6 plugs for the M54 engine cost 135 bux so if one wants to do dyno for this mods, the costs will be 255 bux in total which in my opinion is absolutely waste of time and money.

A better throttle response and better butt feel in pulling power, stable idling and the factory warranty are more than enough.

It's pointless to debate over such small mods that would require dyno to prove...

That's just my opinion. Hit me back, anybody..

Nonetheless, I am goin to get em too.

Cheers and happy modding

Jack, no worries about the dyno session, i will take on the cost and find out the actual gains (relative of course cos the base line will be taken as reference) Shaun pointed out a good point that the gains of 15hp seem too good to be true. I too cannot believe it. I am also interested to find the actual gain when we keep all the plugs new.

Bros, Please wait for results.

Cheers.

 

[Shaun]

Re: Spark Plugs

Thanks for starting this thread and taking the time to explain what you mean in such detail. I hope there are no hard feelings.

Best regards
Shaun

Rodney, I hope you remember what I said a long time ago about how I like how you are. It still is true. At the same time when there is something on my mind that I see as a valid point I also have to at least mention it. Not a pleasant thing. In any case it doesn't appear to matter because people are still buying or going to buy, lots of the plugs - whether it is out of wanting to try something new, appreciation for your effort, or dislike of me, or what they perceive me as trying to do - which I can assure you is not something I'm doing. Like I said, I hope there are no hard feelings. I'm a little worried at the non-response - makes me wonder if I've lost another old friend. I hope not.

 

[TripleM]

Re: Spark Plugs

Hi Ken,

I got my plugs today and my initial feel from "pure butt" feel is that my car is able to pull smoother to the redline. This is my 3rd set of plugs and is definitely better than my stock plug and the Denson Iridium plug that I changed to 6 mths ago. However, this is based on PURE BUTT FEEL.


Cheers!

U hv sensitive BUTT......................

 

[yendor]

Re: Spark Plugs

shaun.
at the start of this thread, i wanted to leave the figures out. why?
i too cannot fully scientifically substantiate the gains. Ask some of the users and they can vouch for gains. i provided the figures based on std electronic components. in actual applications, i suspect the rise time is longer but i cannot confirm. lets settle on the concept first and then perform experiments to verify validity. from data collected, we find the exact relationship.

like what triple m said, spending a couple of hundred $ on $135 is not worth. but in the interest of knowledge i don't mind finding out. the only issue that remains is which dyno? the rolling road dyno has been sold. now waiting for some special plugs that can measure cyl pressures directly. i think this is the most accurate method. pls wait for results.

i did not reply earlier cos i was busy. no worries about hard feelings.

cheers
rodney

 

[Welbo]

Re: Spark Plugs

U hv sensitive BUTT......................

I don't think I am the only one this few days with sensitive BUTT kekekeke

Cheers!

 

[Orh LuLu]

Re: Spark Plugs


Rodney, you hv a PM.

Pak Triple M, my butt not sensitive but itchy.. kekekeke

 

[reardriven]

Re: Spark Plugs

From my experience, spark plugs by themselves are unable to yield any measurable gains on the dyno; that is even if the car in question were to pull a few runs, the variance in the reading alone using the same plug would already have negated or "masked" the gains (if any at all) of different plugs. Butt-dyno on the other hand is usually more of placebo effect than any real gains.

One of the big determinants of an existing engine output is volumetric efficiency and for most NA road-going engines are somewhere in the region of 70-85%. Without applying forced induction, it is difficult to get substantial power gains from an existing engine by just tweaking ancilliaries without changing the rev limit of the engine. Sure you can have *more* power if you can make your M54 rev to 10,000rpm safely (assuming engine internals, ecu, cams, etc have been engineered to match).

From the consumer perspective, it's "to each his own":
- if the consumer is a hardcore racer who has to win every traffic light GP, it's best he considers changing car (M3/5/Evo/STI/Skyline) *or* adding forced induction ie. turbocharging/supercharging.
- if the consumer is not hardcore but just softporn , playing around with air filters, exhaust, spark plugs will not hurt but rather is a creative outlet to occupy spare time and detracts from dangerous driving or speeding. Yea?