Spark plugs 101

Spark plugs are at the center of your cars ability to run and make power. By some its the most over looked and misunderstood component in the car.For the most part your going to get the crowd that isn’t going to believe this key component is going to make a performance impact.

Before we get too far in lets get some facts out there about spark plugs.

Lets start with a quick 101 on what plugs help do.

SPARK PLUG BASICS:
The spark plug has two primary functions:

* To ignite the air/fuel mixture
* To remove heat from the combustion chamber

Spark plugs transmit electrical energy that turns fuel into working energy. A sufficient amount of voltage must be supplied by the ignition system to cause it to spark across the spark plug’s gap. This is called “Electrical Performance.”

The temperature of the spark plug’s firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called “Thermal Performance”, and is determined by the heat range selected.

It is important to remember that spark plugs do not create heat, they can only remove heat. The spark plug works as a heat exchanger by pulling unwanted thermal energy away from the combustion chamber, and transferring the heat to the engine’s cooling system. The heat range is defined as a plug’s ability to dissipate heat.

The rate of heat transfer is determined by:

* The insulator nose length
* Gas volume around the insulator nose
* The materials/construction of the center electrode and porcelain insulator


A spark plug’s heat range has no relationship to the actual voltage transferred though the spark plug.
Or the amount of ground posts used for the function of the plug. Rather, the heat range is a measure of the spark plug’s ability to remove heat from the combustion chamber. The heat range measurement is determined by several factors; the length of the ceramic center insulator nose and its’ ability to absorb and transfer combustion heat, the material composition of the insulator and center electrode material.

The Misconception That platinum, multi post or even the charge core of the plug can lead to pre ignition is simply false. An improper heat rage (too high) can in some cases create an environment more prone to Pre-ignition but Pre-ignition is rare coming from a spark plug.

There are several types of spark plugs available

Spark plug concerns.

How quick will it get up to operational plug cleaning and maintenance temperature.
How efficient is the plug as far as voltage needed to fire.
How is the Fouling resistance of the spark plug.
How much is the concentration of the actual material used in each plug.
How is the over all design of the plug. IE construction and tolerances.

When it comes to brand X Vs brand Y. several things listed above need to get looked at.

The performance and lifetime of the plug center around a few things. One of them being the Core.

We see the core advertised from
standard
platinum
Iridium
Etc.

What dose this mean what is this and how does this effect the performance. What we need to look at further is how much of these Core components is in each plug. While having a platinum core will make for a better more powerful spark over a standard core. What most people don’t realize is the amount of platinum is very important in the performance of the plug.

When there are plug Vs plug debates. It has been seen that not all Platinum plugs are the same. Why is this? this is due to the amount of actual platinum used by each manufacture. There is no actual amount that the core needs to consist of before the manufacture can claim they have a platinum plug. This in part is why some platinum plugs are 2$ and others a 6$ This is the same case with Iridium plugs

So you get the better performing higher concentration of platinum plugs getting solid results and great performance. This ends up showing itself and gaining interest for platinum plugs. From this advancement what you end up with in cases like this is the brand recondition and tradition of one better brand selling another cheaper brand. Who go get the more expensive brand when brand X is way cheaper. While the cheaper brands still have “some” platinum in them the concentration isn’t as high the quality in some cases isn’t as good and you get a lesser plug.

In most cases people are not going to know that there plugs are not running as efficient as they could. A plug with 40% less platinum is still going to fire its still going to work. Its just not going to give the performance of the better plug. So to most people ignorance is bliss.

So there are many factors that play a important roll in spark plugs.

The construction
The concentration of actual material that makes the plugs more powerful
The tolerances of the plugs.

and then there is the actual design of the plug. IE. special features such as Multi post and post position.

Thats coming up in the next installment

Great post! Lots of quality info many (including myself) usually don’t think of or are not aware of. Thanks a lot for taking the time to post all this up.

Great to see this posted up here Justin. How about some more info based on which plug is best for the s4 and why? I’d like to have a firm understanding of why the multi-lash works so well on the S4 where it may not be the best performance wise for other motors.

Great post for sure. Most people don’t understand how plugs work.

Ill add a few quick points. Having more then one location for the spark to land allows you to have more area for the charge. It also will result in more spark when the volts crank up. There is a point where with a single post plug that the Amp isn’t getting any higher and the voltage is limited to only so much because of the one area. What your going to see is that there is a point where the voltage is at a point where its kinda limited due to the amperage unless it can jump to another ground. Having another ground to bridge to requires no more amps but in some respects allows the voltage to continue stay constant or increase but carry more area. The are is very important. Well limited isn’t the best example of words. maybe a video will help.

Someone needs to show me how to embed these videos.

A few things, To touch on what Justin said the material of the core is important. Here is an example of how different a core can be. Keep in mind the plug on the right has a more concentrated tip. Still you can see the difference in spark strength.

http://audirevolution.net/videos/64/spark-plug-material-difference

This is a standard plug. Going through what would be the Voltage increase as the RPM’s increase.

http://audirevolution.net/videos/66/spark-plug-standard-example

This is a great example visually to show what having the same voltage but more ground area can produce.

http://audirevolution.net/videos/65/spark-plug-ground-test.

So what you see here in the last video is that with any plug you can only supply so much voltage to one post before you need to start to push the voltage to supply more. your using Amps to push voltage and due to the fact that the amps don’t go up but the voltage can having more then one ground allows the voltage to spread and go up covering a larger area.

As a disclaimer: some of the things Ive posted are simplified. Ill tell you now. Posting this stuff on AZ isn’t going to help anyone. Your going to get a bunch of barely educated guys who get stuck on several points that have nothing to do with actual system dynamics. AZ seems to consist of people who would rather not be wrong then to be educated. If you want to help people direct them to this post.

Let me further expand.

Note this picture.

http://audirevolution.net/addons/albums/images/743764742.jpg

what you can see is the standard location of the plug to the piston dish. You will notice that there is the ground electrode between the spark and where the fuel will be. This is another limitation of some spark plug designs. When you look at the 4 post designs.

The new Bosch 4 post designs allow the new Air Gap technology to work properly. This leaves a open area for the burn to take place. This will now put the spark right in the path of the fuel. It makes for a stronger more efficent burn. Having more posts not only allows for a hotter spark but a longer spark for a deeper burn. The bosch web site is talking about a 45% longer spark. THAT is huge

http://lightemup.com/spark_plugs/fusion

I really want to leave the voltage conversation open to the others. I would like to expand on the fact that more ground locations help keep the fire voltage down. Fire voltage= the required voltage from the cars electrical system.

What most people don’t understand is that spark plugs work through a wide range of duty. From start up, to part throttle, wide open throttle and then general transition between all three. What gets lots is the plugs performance in transition. Most people are to empty minded to think about how the plug works after or in these situations.

Adding a performance program to your ECU is pointless if the plugs don’t make a strong electrical transition and provide a strong burn when the motor ramps up and there is a quicker timing request.

When you see most of the talentless tuners talk about getting performance from your motor, the only thing they can talk about is “Timing” (we know it goes well beyond just timing) As “timing” will help gain more performance in most cases. The question or thing to think about is what is the “Timing” referring to? Its the timing of the spark. If you don’t have a plug that fires on demand your advance of timing is pointless.

The general thought and concern about there spark plugs only consists of, is the car running. When your looking to get the most performance out of your motor its the little things (or should I say the big little things) like the spark plugs.

There are large issues such as plug response and plug heat transfer. Just adding a few more degrees of ignition timing can increase the cylinder temperature over 100deg. You might want to make sure you don’t have a cheap plug, because we all know we want to get as much heat out of the cylinder as possible

And to further expand on it ill give my example of plugs i tried. I was seeing advertisements of the E3 plugs, which do work great in most cars. SO i was like ill give them a try. Went and bought 90 worth of plugs and put them in. Went for a ride. The car didnt feel as quick, i was like hmmm. So i went and hooked up the vagcom just see if maybe i was getting misfires. No misfires, so i decided to log the car on a 3rd gear pass. Well needless to say i lost some power from those plugs. So i swapped back to the oem ones and went and logged it. All the power i lost was back. I was just happy i was able to get my money back for the E3 plugs. Plugs do make a big difference and running the wrong plugs can rob you of HP, and possibly other bad things.

The sparks plugs i have now are worth 400hp, because thats what i made with them. And without them i made 0hp, so they must be good for 400HP. I can get before and after dyno sheets for the non believers. best mod ever.

very informative. One of the most coprehensive posts Ive seen on this.

While I don’t remember so much what plugs they were I remember putting a split fire type of plug or multipule post plug back in the day in my probe GT. Many a people laughed at me when I said I felt and saw great performance gains just out of a spark plug.

What I think most people also don’t know is that you want a longer spark. not just time wise but length wise. This is why people back in the day would widen the gap on there plugs. The longer gap would provide a much larger burn area. I know this was a big deal on Natural asperated motors

I have a quick question on the spark plug topic. I have seen a few posts on spark plugs and how it does make a difference to have fresh ones in for max performance. However one question that just popped into my mind is… how about the ignition wires? How fast do those deteriorate? With all the heat our engines give off are those wires prone to dry up and crack in there possibly causing loss of voltage? I guess same question can be asked for the coil packs as well. How long before they start being detrimental the whole ignition system?

With the s4 we have coilpacks, so wires are out of the question for us. But with other cars this could come into play. Now the coilpacks we have are exposed to alot of heat which could be part of the reason why they are prone to failure.

Yes this was a big issue on the older A4s. first they made bullet proof coil packs and then they started to cheap out. Now there starting to realize that they need to be alittle better made.

I think there is a way to test the coil packs to see if there getting weak or not. It just sucks because coil packs are such a major issue in making power you would like to know how good they are.

As for the spark plugs. I find I check mine every winter before the snow sets in. pull the plugs and just give them a look over. Its not a bad idea because it will tell you how the motor is running as well.

Some people will never learn, and will debate until the end of the earth because they can save a couple bucks. I do love the videos but like Count said, if this was on AZ they will still try and find a way to argue over it.

Great point. Most people don’t want to learn. They have one or two sound bites and they try to think that is the end all conclusion. Can I place a vote for the dumbest guy on AZ. That squibby guy is dumb as fuck. He is a example of the rest of the AZ attidude. They don’t know much but what they do know they don’t have a full understanding of from this they derail and turn what was a good point into a pointless post.

Fact of the matter is. If your going to get away from the OEM plug you need to openly adress why the oem plug and its specs are not needed in the new plug your using.

I have yet and doubt I will see anyone on AZ back up whay they are switchbing plugs. The best anyone has is… ITs a cheaper plug and my car runs fine with them in. what a joke. They could be doing damage to the mtoor and never know it.

this made me lol

he’s probably pretty bright but that makes him dangerous on a forum…people assume he’s bright about everything. His lsd thread proves that…he’s not.