Rep Power: 812

Is it necessary to change to colder spark plugs with the increased compression. All over I'm reading that too hot a plug causes engine damage, while too cold just fouls the plug. So is it safer to get a colder one?

Also, I'm thinking about going back to regular copper plugs instead of iridium. Thanks for any help.

 
Rep Power: 0

iridium is overrated. Im sure it works, but for the price to pay for something you have to keep on replacing, i'd rather get the standard NGKs.

We use regular NGKs on our Race cars. Plugs are changed almost every run so it gets pricey. but even on street cars. I'd rather change the plugs more often than run an expensive plug and not change for a few thousand miles.

 
Rep Power: 812

So should I use a colder plug for the milled head (higher compression)?

 
Rep Power: 607

honestly, you won't need to. The slight change in compression won't lead to detonation from the stock plugs. Just stay with the same heat range as stock.

 
Rep Power: 329

can you gap to a bigger size and run colder?
Stock gap recomended .040 stock civic D17
can I go 0.43 on the same engine?

 
Rep Power: 812

I was wondering the same thing. I'm taking out my iridiums and just trying some regular NGK v-power plugs to see if it helps the rough idle. From what I've read, those iridium and platinum aren't all that great. I think using anything but regular copper for turbo apps is also a big nono. I'll let you guys know the difference between the regular ones and my old iridiums later.