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Old 01-19-2010, 02:13 PM   #1
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Question Hotter Ignition + Wider Plug Gap

The previous owner of this truck put in multipronged platinums. I plan on replacing them with standard coppers to get rid of a slight miss at idle. While Im at it Im wondering if replacing the OE coil with a hotter coil (which would allow me to gap the plugs wider) would result in better fuel economy?
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Old 01-19-2010, 02:31 PM   #2
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a friend of mine did this experiment on his truck. he got the best gains buy using taylor wires with a hotter coil and making a huge gap increase on his truck. i think he went from like .034 to .055. ended up with a 1-2 mpg increase overall.
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Old 01-19-2010, 02:35 PM   #3
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1-2mpg on a truck is probably a pretty large gain for such a small change in equipment. I wonder what compromises caused the engineers not to design it that way in the first place?
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Old 01-19-2010, 02:49 PM   #4
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my s10 has a .060 gap from the factory...
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Old 01-19-2010, 02:59 PM   #5
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Quote:
Originally Posted by kit352 View Post
a friend of mine did this experiment on his truck. he got the best gains buy using taylor wires with a hotter coil and making a huge gap increase on his truck. i think he went from like .034 to .055. ended up with a 1-2 mpg increase overall.
are you sure its because of the components or the fact that thier new?

id imagine it would do something especially the taylor wires (great wires).

altho i wouldnt mind seeing what happens if someone wants to do this.

i could replace my coil packs (still stock) and wires (been changed twice)
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Old 01-19-2010, 04:20 PM   #6
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On my Buick, I run cold plugs with a tight gap (0.028") for nitrous. In non-nitrous situations, I used to put in a set of plugs with 0.040" gap and 2-3 heat ranges higher, but I found no appreciable difference in any aspect of engine performance in the hotter plugs. (Yes, I have a very strong coil)

-Bob C.

EDIT: That's not to say that it won't help in other situations, I have a pretty unique engine...
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Old 01-19-2010, 07:24 PM   #7
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when he did the experiment he tried a number of different configurations. it all started with the jacobs mileage master system (which produced no gains) and it lead to his latest setup. it basically gave him some ideas. i know he went through a few sets of wires before he settled on the taylors. the mileage master gave him the idea to run a huge gap. it didnt work on the kit but he saw gains when combined with the msd coil and different wires. the jacobs coil did nothing so he switched to the msd. i believe he tried an accel coil at some point and said it didnt do enough.
im sure his original setup was worn but it was only after he tried multiple combos when he came up with his winning combo. it took him a number of weeks and plenty of item returns to get it down.
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Old 01-19-2010, 08:09 PM   #8
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Thanks for the input folks. The coil pack is on the way so Ill soon know for sure.
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Old 01-19-2010, 09:03 PM   #9
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If it helps I had a miss at idle too on my car and shutting the gaps down from 1.5mm to 1.1mm smoothed it out completely.
Locally built version of Chevrolet 3.8 V6 with electronic ignition.

Another thought is the gaps enlarge as the vehicle travels anyway.

Pete.
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Old 01-19-2010, 10:22 PM   #10
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I don't like multiple electrode plugs because they shroud the tip, keeping the fresh charge from reaching the plug gap. My personal favorites are iridium plugs because the electrodes are tapered and pointy. They're expensive though.

I think the manufacturers recomend a slightly smaller than optimum plug gap because the plugs will still fire and work when other components are wearing down. If you keep the ignition and electrical systems in top shape, you should be able to run bigger gaps.
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