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2Addicts | BMW 2-Series forum Technical Topics B58 (M240i) Engine, Transmission, Exhaust, Tuning why gap smaller for higher hp?

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      01-11-2021, 03:50 PM   #1
lixiang7349
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why gap smaller for higher hp?

So I'm going stage 2+ in a few days.
What's the engineering explanation for gapping plugs to a smaller .022 when I go up for 100+ whp compared to stock?
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      01-11-2021, 04:02 PM   #2
PeterWT
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I'd like to know the answer to this as well.
I'm at 30K miles and just replaced the plugs (NGK) and flashed stage 2 MHD.

I checked the gap on the new NGKs and they were all larger than .030. I gapped them to a tight .030 (~.029) because it's my understanding that as plugs wear, the gap increases.
The OE plugs (Champion) all had gaps smaller than .030. I'm not sure why or what to make of that.
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Last edited by PeterWT; 01-11-2021 at 05:50 PM..
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      01-11-2021, 04:28 PM   #3
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more boost, more pressure, more dense air, more air particles between the gap.

with the same voltage you need a smaller gap to effectively make a spark.

smaller gap
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      01-11-2021, 04:50 PM   #4
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Quote:
Originally Posted by delvec03 View Post
more boost, more pressure, more dense air, more air particles between the gap.

with the same voltage you need a smaller gap to effectively make a spark.

smaller gap
Oh that makes a lot of sense thanks!
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      01-11-2021, 06:35 PM   #5
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Quote:
Originally Posted by PeterWT View Post
I'd like to know the answer to this as well.
I'm at 30K miles and just replaced the plugs (NGK) and flashed stage 2 MHD.

I checked the gap on the new NGKs and they were all larger than .030. I gapped them to a tight .030 (~.029) because it's my understanding that as plugs wear, the gap increases.
The OE plugs (Champion) all had gaps smaller than .030. I'm not sure why or what to make of that.
I'm replacing at 7k miles XD
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