Spark plugs

[Boyne]

Hi lads NGK BKR7E, copper plugs how long will they last in bpu supra up to 1bar, is 2.5k acceptable or should i be changing sooner  considering i used to change iriduims every 5k, is there a sign appart from a miss fire when they need changing? 

[rider]

Factors normally affecting (reducing) spark plug life tend to be larger gap giving a longer spark and fuel ratio giving a leaner hotter burn. Platinum plugs for the Supra were spec 60k miles change interval, I think 5k mile intervals for iridium probably means throwing away a lot of useable plugs. My car runs 330bhp at the drive wheels and I've replaced the plugs twice, once recently (in terms of miles rather than years) with the car at 117,000 miles.

Edited September 7, 2023 by rider (see edit history)

[Boyne]

So are you saying the copper plugs will last 2.5k, given they are running perfect when installed?

[rider]

Copper plugs were an every other service item back in the day, the day being the 70's. So typically 10k - 12k miles, I'd say go platinum 60k mile interval like Toyota intended.