Depends! and you can ask me anything. If you install the XP plugs, you get a little better power and fuel economy and a plug that will have no gap erosion over 100k miles. Now if you install a copper core spark plug at say 2.49 each, little less power and fuel economy and you will need to change them at a minimum of 30k intervals. Iridium alloy fine wire plugs are used in most all new cars because the really do work better than copper core or platinum plugs and they require less voltage to fire, something that is vitally important on coil on plug ignitions and direct injection modern vehicles. I have a 430ci windsor stroker in my Mustang, I used to run Autolite racing plugs, switched to the XP iridiums and it starts faster, runs cleaner at low speeds. No difference in qtr mile times, just better street performance
Depends! and you can ask me anything. If you install the XP plugs, you get a little better power and fuel economy and a plug that will have no gap erosion over 100k miles. Now if you install a copper core spark plug at say 2.49 each, little less power and fuel economy and you will need to change them at a minimum of 30k intervals. Iridium alloy fine wire plugs are used in most all new cars because the really do work better than copper core or platinum plugs and they require less voltage to fire, something that is vitally important on coil on plug ignitions and direct injection modern vehicles. I have a 430ci windsor stroker in my Mustang, I used to run Autolite racing plugs, switched to the XP iridiums and it starts faster, runs cleaner at low speeds. No difference in qtr mile times, just better street performance
motorking, thanks for making your self avaiable to us. I like what you have said about the iridium plugs. when i got all my training and follow up training was before iridium plugs were common and never heard about them. can they be gapped with a traditional slide type gaper? do they get damaged from detination? can you send me a demo set of plugs?
You have to be carefull when gapping a iridium alloy p[lug. You cannot use a slide type gapper that touches the centerwire, in fact you should only move the sidewire and be carefull not to put pressure on the centerwire. They are resistant to detonation however that is a function of comp[ression, timing and fuel quality more than anything else. i can send you a set, what cylinder heads are you running?
Whhen installing spark plugs I always use a copper based anti-seize on the threads. Do you recommend that with the iridium plugs? Do they become a problem to get out after being in an engine so long?
The XP iridium plug has a nickel plated shell to fight corrosion. All automakers and plug makers do not recommend using antisieze on plug threads. WHY? Because if you get it on the plug seat (gasket area or tapered seat) it can actually alter the heat range of the plug by changing its ability to transfer heat from the plug to the head. That being said- Lets face reality. It is ok (in my mechanics opinion, not Autolite) to use a VERY SMALL amount on the threads only, being careful not to get it near the seat.
