colder plugs for higher compression

[cmcfaul]

With new JE pistons I think the compression is going to be 9.8 / 1. I am concerned about detonation with a single plug and super unleaded gas. I ordered the following plugs

NGK Iridium BR9EIX


I think stock heat range is 7 for street 8 for track 9 for me.

Anyone see a mistake with my choice?

Chris

73 911 E with DC 30 cam

[rsscotty]

That is what we use. You are making the correct choice.

[cmcfaul]

Perfect

Many Thanks

One more thing to check off on the internal list of good decisions.

Chris

73 911 E

[Dodge Man]

Your heat range is spot on for non-extended MFI plugs. I went the route of NGK Copper Core plugs which were less $$. NGK also has the radio resistor BR9ES if you want old fashioned copper core to test. I got some copper core plugs off Amazon for $2+ each for my stock 9.8 CR CIS 930/10 and it is happy. I even have some Bosch W3 & W4 MFI plugs in the garage if you want some test/tuning pieces. Best of luck