NGK DCPR8EKP or DCPR8EIX ?

[ac427]

Which spark plugs are best from a combustion point of view?

I know the Iridium last longer than the platinum plugs but is there more to it than just that?

[DJAM3]

I've used copper before because it has the best conductivity. You have to change them every two oil changes though. If you don't want to deal with that, go with iridium. They have better conductivity than platinum.

[WestBankM4]

Copper is the way to go, least amount of resistance for the task. Just replace them more often, like your toothbrush.

[ac427]

I've used copper before because it has the best conductivity. You have to change them every two oil changes though. If you don't want to deal with that, go with iridium. They have better conductivity than platinum.

Sounds good. Do NGK make an equivalent copper spark plug for the M3?

[chris719]

Just use the DCPR8EKP. There’s no improvement to be had by deviating.

[0-60motorsports]

Just use the DCPR8EKP. There’s no improvement to be had by deviating.

This.

[WestBankM4]

NGK BKR6E's, copper plugs. I've used them in my E36 M3 as well. Set of 6 runs about ~$20, change them out every 10-15k for peace of mind, that's every 2-3 oil changes.

I know the OEM police are going to pull me over, but copper are the best.

[ac427]

I know conductivity was mentioned but these plugs have a 5kΩ resistor in them to reduce EMI. So i am not sure that would make a difference since it must be in the milliohm range.

[Ramage]

Just use the DCPR8EKP. There’s no improvement to be had by deviating.

I agree that there is little to be gained by deviating from the DCPR8EKP plugs. However, I'm not a fan of the .036 pre-set gap of the platinum plugs, as gapping them can be quite cumbersome.

Personally, I prefer the DCPR8EIX plugs, which have a pre-set gap of .031. Gapping them to .032 is easy, and they tend to cost less than the DCPR8EKP plugs.

For example, here are the Canadian prices from Rockauto:

- DCPR8EKP: $12.67 CAD each
- DCPR8EIX: $9.20 CAD each

Having used all three of the common NGK plugs in my car over the last 14 years, I haven't found one that works "better." If I drove my car more often, I think I would follow what others have suggested and just use the copper plugs, changing them more frequently.