The Iridum plugs are not the old BUR series I used to use. I'll have to get that number for you. I pulled them out of the Renesis crate engines I bought so I assume they are the standard plugs used in the RX-8 car. They look similar to the old style plugs with adjustable gaps but the electrodes are extreamly fine wire. Very expensive (so I'm told) and fragile looking but they work great.
I think that would be the Denso IRT01-31; about $35.00 each. They apparently use iridium for both electrodes. But if they last 10 times as long, it’s worth it.
Kelly wrote:
In case you are not aware of it the NGK B9EGV is available
in Iridium.......BR9EIX part # 3981...........Has a resistor...........
I have found that on the standard B9EGV the ground electrode erodes and the gap gets wider. Having an iridium center electrode may not improve the lifetime; although they are only about $1.50 more than the standard.
Al