Exotic-metal55

I did a comparison between the BMW 7 Alpina one heat range colder plugs that many say they are running in their M157 with tunes. Also have another NGK option that a member said he is using after speaking with NGK for replacements in 8 series colder plug.

BMW alpina is plug on the left. Center plug is stock and plug on right is another alternative posted my couple members.

Before I get started , the Alpina plug is for the 2013 year model cars rated at 540 hp and I think 16 to 18 psi. What I would like to see is the spark plug number for the new 2016 BMW 7 Alpina rated at 600 hp and 20 psi, plus they advertise they use NGK plugs. Anyone have that plug ??




Below are the ALpina, stock and alternate NGK plug from left to right. Plug 1 and 3 are both 8 series or one range colder. Here are the likes and dislikes.

Alpina plug is 1mm longer than stock but I guess no one has had clearance issues with the 1mm delta? Insulator housing is really long compared to stock but the electrode is a little more recessed.

Plug 3 or alternative plug, is same length but uses the regular compression style washer VS nice copper washer on stock and Alpina. Our plugs torque to index, so how the washer compresses could effect the indexing. One plus, electrode and insulator are more recessed. Reach is the same but the seat to electrode ground is 1mm shorter on this plug VS stock but this washer may compress more than the copper washer. One last detail,the plug ground electrode is square on this plug vs the other two have V cut ends. BTW, the V cut ends on the alpina plug are sharp and have rough cut edges. If you use these, I would lightly polish those burs off to avoid hot spots that could cause detonation.

EddieK

Thanks for the BMW "plug"

kponti

https://mbworld.org/forums/w212-amg/...ml#post6677652

Exotic-metal55

Good thread link Kponti.

The plug I show on the far right does have the same seat , reach is the same but gasket is standard compression style. The plug fits well but curious who has used it in the M157? Its the NGK 6706. Our OEM plugs are indexed by 23 NM torque , so we would have to hope that other plugs electrode grounds are lined up with the same angle as stock plugs to have correct index. (Hope works for a girls name but not to good for high $$ motors) . MB claims cylinder damage can occur if plugs not torqued right.

One more word of caution. My stock plugs, on a stock tuned car at 30K miles on them, have more wear and carbon build up than I would want on a performance engine. Even a stock tuned car should consider changing plugs at 30k ish milesIMO. If you add a tune, I would change plugs regardless of what type plug you put in, just to make sure you do not have carbon build up that could cause detonation or other wear hot spots.