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Old 07-24-2008, 04:47 PM   #1 (permalink)
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NGK Platinum vs NGK Iridium? Worth it?

I have read on the net that iridium spark plugs can improve FE. Replacing worn spark plugs of any kind can improve FE. But will iridium spark plugs give better FE than platinum plugs? By how much? I think a set of 4 platinum plugs runs about $10. I think a set of the iridiums will run $30-$40. Are they worth the extra money?

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Old 07-24-2008, 05:04 PM   #2 (permalink)
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If your ignition system is in good shape(wires, coils) I don't think a plug will make a noticeable difference in MPG. I've tried self modifed NGK(kind of like the E3 plug) and Halos and have never seen an increase in FE.I alway go back to just the basic NGK and index them.

I think the only difference you'll see between the two is in how long they last.
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Old 07-24-2008, 06:34 PM   #3 (permalink)
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In sohc engine i saw an increase when going from copper to platinum(autolite, in my escort i saw a 10% increase(30mpg to 33mpg with only thing different plugs and i had done a tune up 10k before with copper)). In dohc enignes and motorcycle/scooter engines i have seen an increase by going to ngk iridium plugs. In the bikes the electrode doesn't dirty ecause of how small it is, each spark cleans off the end so they run alot better than standard large electrode plugs. Check ebay, i got 4 ngk iridiums for about 22 shipped.
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Old 07-24-2008, 09:42 PM   #4 (permalink)
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I'd agree with Lazarus. Platinum and Iridium plugs are mainly there because they last longer, not because of higher performance. IMO check your plugs more often and stay with the cheaper copper.
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Old 07-25-2008, 02:18 AM   #5 (permalink)
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rjacob -

I have Denso Iridiums and I like them. When I first started hypermiling, I got my best MPG after installing them (up to that point). However, that could have been an "MPG bump" from just changing the plugs.

Also, saturnfans.com overwhelmingly recommends OEM plugs for my Saturn. If I were you, I would go to a Honda Civic forum that specializes in your generation of Civic to find out what works for them. This will give you an "informed baseline" for your drivetrain.

Hmmmm, I think I've had them for betwen 45K and 60K miiles. Maybe it's time for a new set.

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Old 07-26-2008, 01:46 AM   #6 (permalink)
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Spark plugs are all about conducting electricity between a gap to ignite the air/fuel mixture. The better spark you get, the more complete burn you get, and the more power you get out of the fuel you're using (and less emissions, too). To get a better spark, you need to use a good conductor. Copper is one of the best conductors available for spark plugs, and is dirt cheap, though it has pretty short life span. Nickel and platinum aren't that great, and are only used by manufacturers because of their extended life span.

Iridium is the best of both worlds. Even though iridium itself isn't the best conductor, it's extremely hard. It'll last the longest of any spark plug tip material (some are rated up to 100K). Being so hard, the tip can be made to a fraction of the size of a normal one. This creates a very concetrated spark in comparison, which easily negates the lower conductivity of the metal. Iridiums are know to ignite lean mixtures that other plugs can't, which would definitely help fuel efficiency.

I had an 86 Celica GT-S, and it ran horribly on NGK coppers. Tossed in some Denso Iridiums, and it ran like a champ. Not sure what was wrong with the car, but it really liked iridiums. I'm running NGK Iridiums on my current MR2 Turbo, and it likes them just as well.
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Old 07-26-2008, 03:34 AM   #7 (permalink)
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i found these... PulstarTM Pulse Plugs - OFFICIAL SITE - Fight back against the high cost of fuel, improve your car’s performance, and help reduce greenhouse gas! they seem ok but i havent done any other research on them yet. just thought i'd share
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Old 07-26-2008, 03:47 AM   #8 (permalink)
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Blue Bomber -

You made my Google :

Iridium spark plugs by NGK and Denso
Quote:
Service life of some OEM Iridium spark plugs can be as much as 120000 miles with very little degrading of performance in that lifespan. NGK Iridium IX types have a centre electrode tipped with Iridium alloy with a 0.6mm diameter. NGK believe this gives the optimum balance between performance and service life. Service life estimates can be up to 60000 miles for normally aspirated car engines and up to 20000 miles for motorcycles - this is extremely subjective though, a high revving motorcycle or extremely modified car engine will most likely wear plugs out in a few thousand miles.
Soooooo, it looks like I don't need new plugs for maybe another 50K miles, .

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Old 06-07-2009, 11:28 AM   #9 (permalink)
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Others have touched on this point, but I'm wanting to clarify it a bit.

Because of the metal in the electrode, there is fewer volts required to create a spark, and so for the same amount of power, you should get a hotter spark. A simple copper electrode cannot possibly hope to do that.

I'm hoping this bump will override the discussion on plug indexing, which sounds more like a sale for snake oil.
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I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
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Old 06-06-2011, 12:58 PM   #10 (permalink)
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This is very interesting. I have know clue that spark plugs could have such an impact on gas mileage. And here I have been buying the cheap ones, because I didn't think it would matter. I really appreciate the information here in this thread. I have learned a great way to help cut back on my gas mileage. Thank you.
I am looking for a good delay timer switch, can someone recommend one?


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