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Side Gapping your spark plugs

Al

New member
Joined
Aug 30, 2003
Location
Pittsburgh
Looks like a good way to reduce your spark contact area to me, leading to an increased chance of reduced spark on a normal plug, probably just as likely to decrease performance with stressed use than to see any real increase...

V split plugs, V or U groove plugs, multi electrode plugs etc are all about increasing possible spark contact areas, and not reducing them.
 
side gapped plugs.

That has been a performance spark plug design for many years. I have a bunch of old Bosch plugs that are original to the Porsche 356SC which are a side gap design. It seems like it's worth a try for better combustion.

Best regards,
 
This concept has been around for a while. I've always heard it is a real performance upgrade. Main downside is faster wear of plugs due to reduced contact area for the spark to jump to.
 
I still like my surface-gap plugs in the 140. I will say they made a noticeable difference plus there no gapping them...ever and they really don't seem to wear after 60k miles. That's an interesting idea though on the side-gapping.
 
I've heard of that before, a buddy of mine who owns a performance shop was telling me about it. Although with standard gaps you can blow out the spark with enough boost, I'd think this would only make that worse.... Though it's definately worth a try!
 
Now how will this work with a high-powered coil? Will the wear be unacceptably fast?

http://www.pbase.com/mr740ti/image/40987586
http://www.pbase.com/mr740ti/image/40987585 :-D

Also, it says that you should decrease the gap to help prevent blowout...This seems unnecessary in an N/A application, and would increasing the gap (increasing the spark size??) increase the performance gain?

(Yes, I know that most of this is negligible, but I'm still curious.)
 
own6volvos said:
If one usually changes plugs at oil changes, would wear even matter?

most likely not. But why would u change your plugs @ every oil change!? Or a better question is, how often do you change your oil?!

I was going to change my plugs every year but got lazy. I still get 22mpg out of my 242Ti on a regular basis and the plugs are probably 15k+ miles old.

take care
 
luke242ti said:
most likely not. But why would u change your plugs @ every oil change!? Or a better question is, how often do you change your oil?!

I was going to change my plugs every year but got lazy. I still get 22mpg out of my 242Ti on a regular basis and the plugs are probably 15k+ miles old.

take care

Oil about 4k, and plugs are cheap as hell.
 
Metalgod_Z said:
Now how will this work with a high-powered coil? Will the wear be unacceptably fast?

http://www.pbase.com/mr740ti/image/40987586
http://www.pbase.com/mr740ti/image/40987585 :-D

Also, it says that you should decrease the gap to help prevent blowout...This seems unnecessary in an N/A application, and would increasing the gap (increasing the spark size??) increase the performance gain?

(Yes, I know that most of this is negligible, but I'm still curious.)

with the SuperCoil, spark plug electrode wear is about half again faster that with a stock coil.

the wider the spark plug gap, the faster you will burn out the distributor cap center button and rotor. BTDT

from reading over the linked to article, the claimed advantages appear to come from the necessary [presumed, but unmentioned] indexing of the spark plugs and the reduced gapping. Whoopee

If you are so inclined, then try the side gapping. It may work. And the article does say that gap erosion will increase: because you ARE reducing the area from which the spark can begin, and where it can go to.

If you want improved ionization of the gap and improved flame kernel formation and propagation, then I would suggest indexing of your spark plugs, a gap that takes advantage of your ignition coil's capabilities, and the correct heat range.

The SuperCoil has the 'power' to jump [ionize] a considerable sized plug gap; and to do that with a considerable amount of 'heat'. But that is not it's strongest advantage. That would be the SuperCoil's capability to actually maintain the spark jumping that gap for a longer period of time: anywhere from 0.2milliseconds to 0.4milliseconds longer. It is the longer spark duration that really assists in establishing the flame kernel and making sure that it grows. Add that to the assuredness of the SuperCoil jumping the gap to begin with, and you have a reliable spark ignition.

All this circles back to the age-old debate over which is better: length [distance] of the spark vs the duration [how long lasting time-wise] of the spark. It can be argued either way, depending on operational circumstances.

I am in the adequate gap/longer spark duration/correct heat range camp.

I run Champion RN6YCs [two heat ranges cold] at 0.032in; with a SuperCoil. The cap, rotor and spark plugs perform reliably for 20,000 miles. By then, the plug gaps have grown about five thou, and the cap and rotor are showing the signs of the SuperCoil's heat; and it is time for new plugs and cap/rotor....to maintain flawless operation.

...but that's just me and mine. Do what you want. There are different ways to get there.

TF
 
Thomas, this whole ignition thing has been intriguing me for some time now. Duration sounds like a good start to a proper flame kernel, but what about when using a multiple discharge igintion system like MSD's? I read it can discharge up to 6 sparks per event, these would obviously be short duration sparks though. But would that in theory start 6 flame kernels? Or be better in any way than a single long duration spark? I do have some more questions, but they can wait till I hear back.

Thanks,
John
 
The Aspirator said:
Thomas, this whole ignition thing has been intriguing me for some time now. Duration sounds like a good start to a proper flame kernel, but what about when using a multiple discharge igintion system like MSD's? I read it can discharge up to 6 sparks per event, these would obviously be short duration sparks though. But would that in theory start 6 flame kernels? Or be better in any way than a single long duration spark? I do have some more questions, but they can wait till I hear back.

Thanks,
John

John,

Ionization of the gap is the good start to begin the flame kernel development. And that requires a certain voltage level at a certain amperage level. The width of the gap, and the turbulence and pressures in the combustiion chamber greatly affect what those voltage and amperage values have to be; or what they need to be. The ignition coil has to be able to supply the required voltage at the needed amperage flow, as quickly as it can, once it has been triggered to do so. That is known as 'rise time'.

Once the ignition coil has produced and delivered that required voltage pressure and amperage flow to jump the gap across the plug electrodes, the spark commences. In other words, the ignition coil is triggered, the magnetic field collapses, the induction of high secondary voltage commences [voltage rising], and the gap is starting to tingle in anticipation [ionize] for what is coming real soon. When the spark actually completes the jump, the ionization is complete: we have a spark.

The width of the gap has its effects on the quality and the intensity [heat] of the flame kernel that develops as the spark is sizzling across the gap. A wider gap will require more voltage/amperage to make the spark actually happen, so that can be a good thing. If you can jump the gap, that means that you had to have some heat there to get it to happen.

BUT, if you lack fuel for the flame kernel to feed on, and grow with, the flame kernel can extinguish. That is where spark duration comes in.

By having the spark last longer time-wise, that sizzling continues longer and keeps that flame kernel going longer and hotter so that it can find the fuel it needs to keep burning and growing.

The duration of the spark affects the quality and intensity [heat] of that developing flame kernel; and can affect whether or not the flame kernel continues to grow.

So, what you need is an ignition coil that can develop plenty of secondary [high] voltage and amperage, and can do that FAST.

'Multiple spark discharge', as it is often called, or 'pre-ionizing discharge', as it is sometimes called, is a method that supposedly improves the ionizing of the spark plug gap. It was a way to get around the need for a fast rise time in the ignition coil. Or, another way to say that is: when you don't have the time for 'rise time' then you can use multiple spark discharge to get the ionization going.

I realize that that sounds like double speak. But think of it in the context of a motor turning at speeds over 10,000 RPM: you don't HAVE a lot of time for coil rise time. Especially on a motor with 6 or 8 or 10 or 12 cylinders. At 10,000 RPM, everything has to happen REAL QUICK.

So, you can go the MSD route, or go multiple coils, or do both. The Formula 1 people are the ones that get buggy about such things. To a lesser extent, the top classes of drag racing worry about that as well.

In the world I live and work in, things like MSD are unnecessary. Unnecessary to the point of being a gimmick.

If I can get a single ignition coil that can put out over 45,000 volts at over 6500 RPM on a V8, and do it reliably and consistently, then it can more than adequately do the job on my four banger...unless I wanted to rev it to 13K or more...

....nah, I don't think so. I don't do Formula 1.

What I am saying is this: if someone wants to play with things like MSD, that's fine with me. I don't see a need or a justification for it. But, whatever floats their boat.

HTH; and remember: the above was a brief and very abbreviated comment. I know there are several aspects of MSD theory that I did not address; but which I don't care enough about to elaborate on. I figured out years ago that I don't need anything that MSD supposedly offers; but that's my opinion and evaluation.

Thomas Fritz
...the stealth FTi
 
You rock. I really appreciate how you help me learn the "finer" things in life. Now I've got plenty of keywords to have fun with google.

For my application, I'm just looking to get the best spark I need, no more no less. Think 20-30psi boost from a large turbo and 7000rpm max. So would a fancy coil (accel, jacobs, etc) be all that I need to fulfill this requirement? Would a bosch 139 igniton module (using megasquirt)produce more or less the same results as say an MSD 6A box? Ohh wait, the 6A is an ignition amplifier right? Now I've gotta search to find the what's, how's, and why's of that...

John
 
i think that Accel Supercoil that per_0lund or whatever Per's username is is the one you wanna check out, but TF knows a boatload more about this than i do

and for my n00b addition to spark plug gapping etc....what is "indexing" the plug? Thomas, you mentioned it in an above post, i was just curious...spose if curiosity gets the best of me i could always fire up google...
 
Indexing the spark plug is where you use shims to make sure the open part of the gap faces the intake valve. that way the spark is not "hidden" behind the upper electrode. Makes starting the flame in the cylinder a bit easier.

Edit: By shims I mean washers of various thicknesses so that when you tighten the plugs to the proper torque, the gaps point where you want them.
 
Last edited:
ah, so like thin washers (shims...what have you..) between the head and the plug, which compress but limit the amount the plug can screw in?

if so, that's a hella cool idea
 
Indexing is making sure the gap of every plug points in the exact same direction when you install them. Usually by making a marking on the outside so you know where the open gap is, then screwing them in until where you want them to point. This way you equalize the burn characteristics of each cylinder.

*edit, you guys snuck in there... Humm I've never heard of the shim idea, sounds cool though.
 
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