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Old 06-22-2008, 07:29 PM   #1
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Default Indexing Spark Plugs

Has anyone ever tried this? I know it doesn't make much of a difference on n/a motors, but what about on forced induction?
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Old 06-22-2008, 08:02 PM   #2
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We have four-valve DOHC engines with the plug directly in the center of the chamber. What exactly would you index it to?
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Old 06-22-2008, 08:12 PM   #3
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yeah, the V8 guys would point the gaps toward the intake valve. I guess you could point the gaps between the intake valves but I doubt it would not make a difference but it would not hurt either.
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Old 06-22-2008, 09:33 PM   #4
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Intake valves.
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Old 06-22-2008, 09:37 PM   #5
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i hear it's good for at least 10hp per plug. i'm gonna go spin mine
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Old 06-22-2008, 10:18 PM   #6
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Tried doing this many times on a 275hp Honda B Series NA engine. Did not do **** except for take a few more minutes to install plugs.

Don't waste your time!
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Old 06-22-2008, 10:22 PM   #7
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I would rather know my plugs are all torqued correctly then indexed right to get a .25 hp gain.
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Old 06-22-2008, 10:27 PM   #8
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Try side-gapping the plugs...it works.

I have been doing this since the early 90's.

Tony
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Old 06-22-2008, 10:54 PM   #9
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Old 06-22-2008, 11:00 PM   #10
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effort.
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Old 06-22-2008, 11:27 PM   #11
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Quote:
Originally Posted by mrtonyg View Post
Try side-gapping the plugs...it works.

I have been doing this since the early 90's.
Then you should have plenty of before-and-after dyno charts to post, so we can see the effect of side-gapping upon performance.
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Old 06-23-2008, 12:34 AM   #12
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I would need to see a few back-to-back dyno runs with at least a couple different sets of each plug configuration using brand-new plugs to be convinced. Power and AF's would begin to tell the story.

The indexing thing makes sense, but so do a lot of things that don't actually work better. If there was a computer modeling program that dealt with combustion chamber flow characteristics and flame-front vs. spark exposure and it was SCIENTIFICALLY proven to have your plug "FACE" the incoming fuel/air mixture then it might be worth the time.


I also have to wonder why you can't simply buy a pre-side-gapped plug. Makes you wonder if side-gapping produces a superior spark that Autolite or Denso would know abuot it? I ABSOLUTELY DO NOT BUY the size difference in the little cartoon flames in Chads link. That **** does not fly, but it was a great link so I know what we're talking about.

The same goes for indexing. If it produced even a .1% benefit in efficiency or power output, then it would be industry standard. Every car out there would come like that. Seriously, could you imagine what a car company would give to get .1% for free.

Just for shitz and grins, I'm gonna buy a new set of plugs next time I hit Autozone and do both of these techniques... I'll let y'all know.
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Old 06-23-2008, 01:04 AM   #13
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Quote:
Originally Posted by Joe Perez View Post
Then you should have plenty of before-and-after dyno charts to post, so we can see the effect of side-gapping upon performance.
A bit of sarcasm?

I threw the technique out there...do what you want with it.


Tony
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Old 06-23-2008, 01:10 AM   #14
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Quote:
Originally Posted by mrtonyg View Post
A bit of sarcasm?

I threw the technique out there...do what you want with it.


Tony
Sarcasm? I don't think so. Seeing/Believing method for sure!
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Old 06-23-2008, 01:21 AM   #15
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Quote:
Originally Posted by samnavy View Post
I ABSOLUTELY DO NOT BUY the size difference in the little cartoon flames in Chads link. That **** does not fly, but it was a great link so I know what we're talking about.
To bad we did not have a cartoon pic of that 1.8 oil/water cooler-heater, huh?



Note to self.....Sam understand cartoon pictures. Only.
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Old 06-23-2008, 01:43 AM   #16
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I don't endorse this method of spark plug molestation in any way shape or form. Especially the weird cartoon spark it produces in your motor.

I merely posted a link i found via google, didnt' even look at the damn page actually.
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Old 06-23-2008, 01:53 AM   #17
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Cartoon Powah Ftw
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Old 06-23-2008, 11:58 AM   #18
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Quote:
Originally Posted by samnavy View Post
I also have to wonder why you can't simply buy a pre-side-gapped plug.
Well, you sort-of can. Here is a snipped from NGK's racing plug chart:




Pretty much any ground electrode configuration you can imagine, they've produced. Top-gap, side-gap, diagonal-gap, recessed electrode, even one style with no ground electrode at all (the spark simply jumps across the surface from center to outer.)

Source: http://www.ngk.com/charglossary.asp?...g+number+chart

Trouble is that all the research I can find pertains to two-valve American engines with asymmetrical chamber design and offset plugs. Said research generally indicates that gains of up to 1% are achievable with proper dyno testing to determine the optimum orientation, and that said orientation is different for different motors. This is probably a worthwhile expenditure for teams in NASCAR and other mega-budget series running pushrod engines, but I just can't see it paying dividends in an engine where the plug is in the center of a symmetrical combustion chamber.
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