List of spark plugs available in multiple heat ranges for the VQ35:

Brand-------------------Stock #-----------Heat Range

NGK Iridium
LFR5AIX-11---------- 4469------------- Stock heat range
LFR6AIX-11---------- 6619-------------1 step colder
LFR7AIX--------------2309-------------2 steps colder


NGK V-power (standard plug)
LFR5A-11------------- 6376-------------Stock heat range
LFR6A-11------------- 3672-------------1 step colder


Denso Iridium
IKH16------------------------------------Stock heat range
IKH20------------------------------------1 step colder
IKH22------------------5345-------------2 steps colder
IKH24------------------5346-------------3 steps colder
IKH27------------------------------------4 steps colder


I searched the threads, but could not find one location of reference for spark plugs. These are just the ones that I did research on. However, if you know of more plugs, please let us all know!

 

Do you have the numbers for copper plugs?

 

I will try to find them for ya!

 

what can you tell me about the pros and cons of going to a 1 step colder plug as opposed to the stock heat range?

I want to get the NGK Iridium plugs but I have no idea which level in the heat range that I should get. Can anyone help me?

gracias

 

If you are lightly modded or stock you don't need to worry about colder plugs. Just get LFR5AIX-11---------- 4469------------- Stock heat range if you want the NGK Iridiums.

 

thanks for the quick response, I'm off to ebay. Sparkplugsource has these plugs (6) for $38, yes they are new NGK, awesome.

 

technically an IKH20 is 2 steps colder than stock...though I don't think they make an IKH18

 

The numbers that I posted came from NGK and Denso themselves. Let me know if you are absolutely sure about this and I will call them back to confirm.

 

Thanks for the part numbers, and the disclaimer. We don't need stock 350Z drivers posting “I went to a 2 step colder plug, and my Z doesn't seem to have more horsepower. In fact, it runs like crap!”

 

Which plugs for my 300 hp Z?
I've crawford plenum, popcharger, UR pulley, test pipes, invidia G200...
Thanks for your help....

 

Subscribing.

 

Ordered on ebay, total price including shipping and sales tax, came to $44. Check it out, I am anxious to put these pups in.

 

Nobody???

 

stock heat range

 

Thanks

 

What is the gap on the irduim (stock heat range) and what is the gap on the 1 step colder (heat range).

 

Off the top of my head. I believe it.44 for both and .34 for the 2-step colder

 

I am lost.. I some some n/a mods , I had seen 1 degree cooler really helped hp from another member , I cant remember what mods or or was FI. What would help me with my mods and can I get these at auto parts? I was about to go get some Iridium plugs like my father put in his Jag, but now I am confused someone please help? I want to get them today and change tonight. I want a long lasting plug that will help my performance any ideas.

 

just use the stock heat range...there is absolutely zero need for colder plugs with typical bolt ons

the colder plug is not what is helping the guys...the fact that their old plugs need replacement is where they are seeing any "gains"

 

So the cooler plug will not help me at all?