VQ35 NA build, what plugs?
 

So i have a 2004 G35 with a Vq35DE, obviously
anyhow i have some NA mods with it, full 2.5" catback, intake, plenum spacer, and will be installing my high flow cats in a few weeks time,

eventually that will be my build, will not consider headers.

i want to get an Osiris tune during the summer time

now my car is currently parked and i have time to work on it, i was thinking about replacing the spark plugs. with the build the way it is and getting a tune, i was thinking about advancing the timing by 2 degrees and going with a hotter spark plug. now the stock plugs are a #6, would a #5 be beneficial? or should i stick with #6 heat range?

your input is appreciated.

Usually, you want to go colder plugs as you make more cylinder pressure, which can caused by boost or higher rev.
For your settup, it's hard to say what will work best, but factory heat range will just work fine for what you're getting.

As stated above.

To my understanding (and what I have used different plugs for), is that a “colder” plug has more ceramic for cooling purposes.

A cars plug needs to hit a certain tempature range to make sure there is no crazy deposit build up. However if you go too hot (less ceramic area for cooling), this allows for detonation, and you will get ping. When adding more pressure to the cylinder (and heat), you need to find a way to combat pre ignition, detonation, or ping whatever you want to call it, so in part you move to a colder plug (usually along with higher octane gas and a tune).

In your case, I can’t imagine adjusting the timing would result in enough extra heat and pressure in the cylinder to warrant a colder plug, so sticking with the factory suggested would probably work fine. Going to a hotter plug can only cause you issues, and I cant imagine why you would want to do it.

Generally I have only seen Colder Plugs come into play in boost/High compression NA Builds. I have NO Nissan Engine expereince, but i would imagine they are the same. Someone correct me if I am wrong.

Stay with the stock heat range unless you start increasing your compression ratio, most of the stuff you have done is just "bolt on" power adders. Basically you have freed up your entire intake and exhaust allowing your car to move air into the engine faster and let exhaust flow with minimal back pressure. Advancing the timing or changing the stock tune wont be an issue either as factory tunes are usually pretty mild just for reliability and sustainability for every day driving, so a colder plug isnt really required; however you could move up to a plug that fires better such as an iridium plug or something that has a little more zap to it, but even this isnt required.

Hmmm I thought colder plugs were necessary for FI/race. But I thought for NA a hotter plug would help. I guess I was misinformed. Okay standard plugs it is. Thanks guys
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An engine with a specific output relative to it's displacement and number of cylinders will require the plugs to be able to dissipate heat at a certain rate in order to stay cool enough to not cause pre-ignition, but stay hot enough to do their job without fouling.

Too cold, they foul. Too hot, you might get preignition or possibly detonation if chambers get to hot in general (oversimplifying).

Therefore it's very rare to need to go hotter - only colder to avoid preignition as specific output goes up.

A very loose rule of thumb is to go one step colder per 100hp over OEM as a guidline. Beyond that you need to evaluate the plugs when dyno tuning.

My motor makes roughly 150hp more than stock and works good with one step colder. (NGK 7 heat range - pretty common for many pent-roof chamber forced induction motors).

I would stick with stock unless the manufacturer of whatever chip you decide to run recommends otherwise.

leave the #5 plug in it. thats the stock range and you dont need anything fancy or colder with what you are trying to do.

im currently running a #9 plug (about 4 ranges colder). sounds a bit ridiculous but its working. lol

isn't it # 6 right now?

Yes for N/A a colder plug should only be used with increased cylinder pressure (more pressure=more heat). Spark plug heat ranges are based upon how far the electrode protrudes into the cylinder. If it protrudes deep into the cylinder, the plug loses some ability to transfer heat to the cylinder head. If it protrudes less into the cylinder the plug can more easily ttransfer heat to the head=colder plug. Tip: DO NOT use anti-sieze on the plug threads!! Modern plugs have a special plating on them to prevent electrolysis between the steel plug and aluminum head, also the plug needs to ground to the head properly in order to fire.