Want to know what Denso spark plugs are better

Stay OEM, Nissan/Infiniti vehicles are pretty fickle about their ignition source and you really will not see any type of noticeable gains
 
Denso Iridium Power plugs(IK16) are better than platinum plugs due to having a smaller .04 mm electrode that generates a hotter spark while using less volts from the electrical system which means a more efficent running engine and better MPGs. However, the double platinum plug will last longer than the Denso IK16. According to Denso, the IK16 only lasts 30K miles due to the smaller hotter electrode. Denso do make an long life iridium plug that will go 120K miles than has an .07mm electrode which performs better than the platinum plug as well. The platinum plug has a .09mm electrode I believe. I use the IK16 plugs in my FX45 and have noticed a great improvement in engine response and MPG over the factory platinum plug. Butt Dyno approved. Therefore, I do not mind changing my plugs every 3 years or so. P.S. the newer Infiniti cars have Denso iridium plugs installed as OEM now instead of the double platinums plugs.
 
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Just did my spark plugs, Denso Iridium IKH16 on my fx45 in about an hour, its pretty straight forward . Only on driver's side you have to take airbox with filter out in order to get to the coils. And the last plug on drivers side is a bitch to get it out(very tight on space, but I used 2 small extensions and a magnet.
 
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Anyone know the Denso Iridium spark plugs we need to go a step colder than stock? I believe the IKH16 are stock....I thought they were the IKH20
but I can't find any that say they will fit our engine...
 
IKH20 is the correct one, they have some threads about it on the 350Z forum. But unless you're already having pre-detonation or knock on your plugs, colder plugs won't do anything for you. Only real benefit is if you're boosted or if you have really, really low octane gas.

How rich/lean you run is not dependent on plugs. Tuner may be able to advance timing a tiny bit more with colder plugs, but on a bolt on motor, the difference will be very minimal. Colder plugs also don't idle as well and they tend to foul quicker. If you look at NGK's own website, they basically recommend one step colder for every 75-100 hp gain. I've generally followed that rule of thumb with decent results ie, on my boosted Maxima w/ 200 hp over stock, I ran 2 step colder. And on my wife's old boosted Integra, I ran 1 step colder with +70 hp over stock.

But on my BMW, I'm at 100+ hp over stock and using stock heat range plugs. Guys are running north of 600whp on their 335's with stock plugs as well. These cars are factory boosted though, so it's not like modding a non boosted car. Still, IMO colder plugs are pretty much unnecessary without significant power gains. People just like to run them because they're the same price as OEM heat range and it counts as a "mod".

I run the IKH16 plugs right now w/ typical bolt ons. Later this summer, HFC's go on and Osiris, we'll see if there is any issues with stock heat range, but I doubt it.
 
shadow191 said:
IKH20 is the correct one, they have some threads about it on the 350Z forum. But unless you're already having pre-detonation or knock on your plugs, colder plugs won't do anything for you. Only real benefit is if you're boosted or if you have really, really low octane gas.

How rich/lean you run is not dependent on plugs. Tuner may be able to advance timing a tiny bit more with colder plugs, but on a bolt on motor, the difference will be very minimal. Colder plugs also don't idle as well and they tend to foul quicker. If you look at NGK's own website, they basically recommend one step colder for every 75-100 hp gain. I've generally followed that rule of thumb with decent results ie, on my boosted Maxima w/ 200 hp over stock, I ran 2 step colder. And on my wife's old boosted Integra, I ran 1 step colder with +70 hp over stock.

But on my BMW, I'm at 100+ hp over stock and using stock heat range plugs. Guys are running north of 600whp on their 335's with stock plugs as well. These cars are factory boosted though, so it's not like modding a non boosted car. Still, IMO colder plugs are pretty much unnecessary without significant power gains. People just like to run them because they're the same price as OEM heat range and it counts as a "mod".

I run the IKH16 plugs right now w/ typical bolt ons. Later this summer, HFC's go on and Osiris, we'll see if there is any issues with stock heat range, but I doubt it.
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Thx Shadow....very good info here. The reason I was asking was because I'm also planning to do Osiris this summer and was wondering if going a step colder
on the plugs was necessary or even worth it. I know going FI you definitely should go colder but I was wondering if I should with only a tune as well.

Meme405 just did an Osiris tune and went with the colder NGK plugs.....and said the tuner recommended it. But I think you may be right and it will not
make much of a difference unless you are making huge power gains.
 
Some tuners will recommend, some won't. It's more of a safety measure than anything. Personally I don't like to modify things just because, so I leave as much stuff stock as possible unless it actually makes a difference. If your car has never pinged or knocked, you don't need it. If you add some mods and you're getting knock, then consider it. I've personally found that colder plugs foul faster so unless I have to run them, I won't.
 
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