B58 coils and NGK 94201 plugs

Apr 1, 2017
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It looks like the ngk 94201 B58 spark plugs would be a good match for this setup. It’s a step colder and the dimensions are identical to the 97506. Plus the terminal is flat.

Would be interesting to see if it we can run the 94201 stock gap (0.75mm) with the B58 coils @ 25 psi.
 

Blue Lightning

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It looks like the ngk 94201 B58 spark plugs would be a good match for this setup. It’s a step colder and the dimensions are identical to the 97506. Plus the terminal is flat.

Would be interesting to see if it we can run the 94201 stock gap (0.75mm) with the B58 coils @ 25 psi.
I think the plug's I'm running are the NGK 97506
 

Blue Lightning

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The 94201‘s Centre electrode has a diameter 40% smaller than the 97506.

The smaller the electrode diameter the less the voltage required for the spark to jump the gap.
Doesn't that also mean the 94201 will run hotter, since there is less metal to conduct the heat away ?.
 

mikeseli

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Hmm, how do you think they managed that then. as a thinner electrode usually means the plug runs hotter.
It’s not the diameter size of the electrode tip that is important to determine heat range of a spark plug. It’s how much plug porcelaine insulator is exposed at the electrode face. More there is porcelain acting as conductive insulation the more the plug is colder.
 
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Blue Lightning

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It’s not the diameter size of the electrode tip that is important to determine heat range of a spark plug. It’s how much plug porcelaine insulator is exposed at the electrode face. More there is porcelain acting as conductive insulation the more the plug is colder.
Well the Porcelain doesn't conduct much heat. But it would certainly shroud the central conductor from absorbing more combustion heat. Though I think I will stick with the 97506 plugs for now. As I'm really not convinced a smaller tip is a good thing. I mean my engine runs pretty sweet right now even with N54 OEM coils. So with the B58 coils its going to get double the energy even with the same dwell settings.
 

fmorelli

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I'm wondering about the washer on these 94201 plugs. I've seen photos of both copper (solid) washer and a new style of aluminum crush washer. I say new because the typical spark plug aluminum crush washer is a use-once design, which is what made me leave the 95770. I've never seen this new style of aluminum washer on the 94201. I've stuck with the 97506 which runs a copper crush washer that is solid and can be re-torqued.

Here are the 3 style:

97506 solid copper crush washer:

0154049_ngk-97506-silzkbr8d8s-laser-iridium-spark-plug_550.jpg


95770 - standard aluminum use-once crush washer:

95770.jpg


Finally the new 94201 with some kind of new-style aluminum crush washer:

94201.jpg


Has anyone handled these plugs and inspected the crush washer. It looks segmented in the photo (crush type?). Can anyone confirm if it is a solid aluminum washer or a segmented washer? Thanks.

Filippo
 
Apr 1, 2017
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The other thing is the terminal design. The b58 plugs have a flat design that goes with the b58 coils.

The 97506 has a cup design which I suspect has less contact area to the coil.

In most papers that I have read - smaller core diameter does better in getting the arc across to the shroud largely due to a lower voltage requirement ...

The main idea is whether with the smaller voltage requirement, flat terminal, larger energy displacement - we can get the spark arced with stock gap size (0.75mm) with 25 psi boost.

Waiting for the stock valve cover brackets to be available and have this tested out ...
 
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_Calle_

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The other thing is the terminal design. The b58 plugs have a flat design that goes with the b58 coils.

The 97506 has a cup design which I suspect has less contact area to the coil.

In most papers that I have read - smaller core diameter does better in getting the arc across to the shroud largely due to a lower voltage requirement ...

The main idea is whether with the smaller voltage requirement, flat terminal, larger energy displacement - we can get the spark arced with stock gap size (0.75mm) with 25 psi boost.

Waiting for the stock valve cover brackets to be available and have this tested out ...

I fully agree with U.
Due to the thin electrode, the energy is more concentrated.
 
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_Calle_

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Jul 7, 2017
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It looks like the ngk 94201 B58 spark plugs would be a good match for this setup. It’s a step colder and the dimensions are identical to the 97506. Plus the terminal is flat.

Would be interesting to see if it we can run the 94201 stock gap (0.75mm) with the B58 coils @ 25 psi.
The B58 spark plug is two step colder as the stock spark plug.


NGK 95770 (ILZKBR7B8DG) <- 1 step colder
NGK 97506 (SILZKBR8D8S) <- 2 step colder
NGK (SILZKBR9F8S) <- 3 step colder

NGK 94201 (SILZKGR8B8S) <- 2 step colder (B58)

only that we all speak of the same.
 
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Apr 1, 2017
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Been working on tunes with the b58 coils on the n54 for some customers.

Noticed that coils that look like the one on the right tends to misfire.

Got a feeling that the shorter snout and bogus looking seal on the coil are signs it’s a China counterfeit.

The coil on the left is a BMW coil. So far no issues.

Comments ?

 
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