pimpjuice

I am just wondering which sparkplugs to get. I know the ratio is -.004"/50+hp but I have no idea what the gap is on 1 and 2 step colder.

I am thinking about going 2 step colder, which would mean I would have to buy Denso instead of NGK. I don't hear many of you buying Denso though, any reason why?

Let me know what you guys think.

Thanks!

HitManSE

iTrader: (1)

Well, it all depends. How modded are you?

If your running N/A then stick to normal platinum plugs

If your running a mild shot of nitrous (100 or less) then 1step should be fine.

I would not suggest 2-step colder unless your packing atleast 400whp so thats just out of the question.

Keep in mind with colder plugs you actually lose power under normal operation, so dont overestimate what you need. Espeicially with nitrous, because you will suffer a loss in N/A mode.

Btw-The spark plug gap itself had nothing to do with how cold the plugs are.

Here is some reading material:
http://www.centuryperformance.com/spark.asp
http://www.carcraft.com/techarticles/64378/
http://www.nightrider.com/biketech/spkplghnbook.htm

pimpjuice

Thanks for the links. Hopefully I can join the 400+ hp club here shortly. I plan on increasing my boost here pretty soon when I get my DFMU in. I'm thinking about going with the 2 step colder though.

-.004"/50+hp: is this the equation I would use on a stock plug?

Also what is everyone else running? One step, Two, or just regap stock ones.

HitManSE

iTrader: (1)

No prob, good luck going into the 400+whp club, thats packing quite a punch!
Be careful with it though, im sure you need to lecure regarding that matter.

As for the .004"/50+hp...well Ive never personally been one to re-gap the stockers. Its not going to effect how the plug dissapates heat so there isnt any real reason to do it IMO. .004" is a very small decrease & I doubt there will be much of a difference.

As for what every1 else is running, Im no so sure but id guess atleast 1-step colder for most of the seriously modded guys. I dont know how many are running 2-step but then again, not too many people actually need that.

pimpjuice

You're probably right, I just want to make sure I get the right ones. I'm gonna go poll the 350z forum to see what the FI guys are running there.

As far as the gap, someone on the 350z forums said "I also had to gap them around thirty to prevent the boost from blowing the spark out". This might be the reason for decreasing the gap slightly, but who knows?

HitManSE

iTrader: (1)

Thats understandable, I would want the correct ones for my app as well.

I dont want to say "yeah thats fine" with the gap issue, because ive never personally done that. Never wanted to mess with it. I dont want to give bad advice, so I dont want to really comment on it, you know what I mean...

I would also suggest the smartest thing to do is reasearch it. Im sure some of it will be explained in atleast one of the links ive given.
Its possible the guy with the Z was running on stock plugs that have been re-gapped but like you said

pimpjuice

He re-gapped his NGK Copper one step colder plugs. Which also brings up another puzzling question. Copper or Iridium. Many of the 350 guys are running copper plugs because of the heat dissapating quality of the metal. They say that the tip of the iridium plugs get to hot and can still cause detonation.
I will do more research though and figure out whats best for my application.

slimer

iTrader: (13)

copper is also a better conductor. you have to understand that they wear out sooner

HitManSE

iTrader: (1)

If your going to get colder plugs, id suggest copper. They wont last too long (10K topps) but it will do the job just fine. Copper is tried & true. I dont have too much info on iridum though.
Id pull the plugs every oil change just to check them out. All depends on how much power is being produced. The more power your packing, the faster you will eat up plugs.

pimpjuice

Sounds good.

Thanks for your help guys.

HitManSE

iTrader: (1)

Sooner then later

stephenlc

iTrader: (1)

I would say go with copper because they are cheaper and you have to replace them often. That way you always have fresh plugs in your car insead of spending lots of money and having to replace the plugs once they get old around 60k.