Hey guys,

Time for spark plugs in my 350. I understand OE is the Denso Iridium Long Life (3473) plugs. But I've heard from some "power heads" in my area that running copper plugs are more efficient. I understand I'd have to change the plugs more often but do any of you agree with this. I was thinking of running Denso Copper (3120) plugs instead for about 15k instead of the 60k that we can get out of our Iridium plugs.

Thanks guys, John

 

IMO use OEM. This engine was designed to work with these plugs.

It's not like an old V8 where tinkering and changing things like plugs can produce benefits, we're talking about a more sophisticated and finely tuned engine.

 

Agreed, use that the engine was designed to work with. Coppers are "old" technology and get for vehicles that need to swap plugs alot more often.

 

For cars that come with Copper (actually all plugs are copper core these days, "copper" plugs are actually steel electrode), you can use platinum (electrode only), double platinum, iridium, etc with no problem.

But for a car that came with iridium, don't downgrade to "copper". The reason is the electrode diameter is usually smaller on precious metal plugs and therefore firing voltage requirement is less than the larger steel electrode "copper" plugs. Steel plugs need a larger diameter to withstand the wear because it is not as hard as platinum or iridium.

So if you insist on "downgrading", you will either need to use a narrower plug gap and / or higher voltage that your coil may not provide. As a result you will get less mpg and more wear on the coil (and probably fry it sooner).

You would be better off just not changing the plug instead of using "copper" in this case.

 

I'm not dissapointed at all to see these responses. You guys have very valid points. OE it is!

Thanks guys

 

Can not beat OE. Lots of car history with Toyota.