I'm about to remove the entire intake plenum to install the Motordyne Iso Thermal intake mainfold/plenum gasket. The plugs will be staring at me, begging to be replaced. I have 68K miles on my G and figure this is an ideal time to put in new plugs. Does anyone know what type/brand of plugs our G35s take? Iridium? Platinium? NGK? Any help would be appreciated.

 

NGK are stock, but I will go look up the part number when I get off work.

I was gonna do this in the next week or so, I am almost to 60k miles.

 

Spark Plug - Std. Platinum - NGK PLFR5A11 <-- Stock G35/350Z plug
Spark Plug - Cold Platinum - NGK PLFR6A11
Spark Plug - Hot Platinum - NGK PLFR4A11

Spark Plug - Std. Irdium - NGK LFR5AIX-11
Spark Plug - Cold Irdium - NGK LFR6AIX-11
Spark Plug - Std. Iridium - Denzo IKH16
Spark Plug - Cold Iridium - Denzo IKH20

 

what's the difference betweeen iridium and platium parkplugs?
does it affter GPM or engine performance?

 

The little I know about iridium tells me that you won't see much difference in anything unless you are running FI boost.

I looked this up on a spark plugs page from the UK:
Thanks DaveO, I just sat down to look those up.

You might see a little better mileage (0.5 mpg or less) with the hot NGK platinums but you will run your cylinder temperatures up as well.

After 69k, I think you will see an improvement in idle, mileage and response by changing them with the same stock part number

the metal in iridium plugs WILL last longer, maybe 20% in a normally driven car. will it make a difference in your car? probably not a cost effective one. You will pay 70 bucks for iridium plugs and about 30 bucks for platinum plugs. It is your call. Personally, that 40 bucks could be put towards your next mod.

let us know if you try them, i have considered buying them in the past.

 

The last time I looked NGK Iridium Plugs could be bought for around $7.00 a piece off the internet from Club Plug. I was surprised that they want about $11.00 each for the NGK Platinum Plugs. I bought a set of one step colder NGK PLFR6A11 plugs from Everything G35 for $7.70 each last summer.

 

Thanks for the replies! I believe I will stick with the stock NGK plug.
Does anyone know what the gap should be? Where to buy? Stealer or Auto Parts store......duhhhhh! Since I will need them within two days, an internet buy is out of the question.

 

The plugs are pre-gaped, however it doesn't hurt to verify they're 1.1mm or 0.043". Be careful... don't damage the platinum.

While I never personally tried, I doubt if you'll find these plugs at any auto parts store. Your best bet is probably a local friendly Nissan or Infiniti dealer (but you won't like the plug's list price).

Be sure to properly tighten the plugs to 18 ft-lbs (216 in-lbs) using a quality torque wrench. A stripped spark plug hole is really ugly.

By the way, I wrote the step-by-step "How to: Spark Plug Change Out" article that was published in the Summer 2005 Issue of Sport Z Magazine.

 

I did my homework: Stealer price for the NGK PLFR5A-11 is $11/plug
O'Reilly Auto Parts has them in stock: $9.89/plug.
One other autoparts store had them for $12+change.
So I'm running down to O'Reilly to buy these plugs. I did get the Summer 2005
issue of SportsZ Magazine with the instructions on changing plugs.
I will be documentating my plug change with digital photos and will
post here on G35drivers.com for all to enjoy!

 

The info posted above about the Denso plugs is true. you would need the IKH16 for a stock G35. Believe it or not, they really do make a difference. And for a little something extra, you can even consider setting your plugs with special crush washers so that the gap opening is pointing toward the intake valve - more optimal burn and even proven to be good for a few extra ponies. It's a proven tuner trick in the drag racing arena over many many years. ;o)

We have these plugs on sale and ready to ship if others are interested. I know Cato said he needs his by this weekend so onine ordering with shipping time is not feasable.

But for future reference and others ready to change the plugs - convenience and a better price than you'll find at your local auto parts store, consider us! ;o)

https://g35driver.com/forums/showthread.php?t=68842

Thanks for your support!

 

I stand corrected Cato and am looking forward to seeing your photos.

 

somebody sticky this thread or put it in the FAQ's. it will be helpful later on.

 

OK, but now I will need to keep the pictures clean! hehe

 

Nice info. Can this thread be stickied? BTW, I'm finding the NGK std Iridiums for about $40 shipped.

 

Do a lot of guys run 1-step colder plugs? I know DaveO didn't have FI. I wonder how many others have done this.