Spark Plugs

[Guest kirby_armstrong]

Just decied to change the plugs in my R33, and got a pretty big shock (no pun intended) when I got some prices on the Platinum plugs, It already had AUTOLITE AP 392-11 plugs in it. I cross refenced it with NGK and got the part number of pfr5g-11 ($20.99ea) for the platinum ones and BKR5EIX-11 ($21.99ea) for the iridium,

Question???

Whats the difference between them other than price.

And can anybody get them cheaper any where else????

I am also chasing a HKS or Trust Dump pipe for a R33 GTS-T I've rang JMS and Just Jap and they dont have any brands that I know.

Thanks for your help guys

[PranK]

hey man, i have the iridiums in my car - i paid $15ea for mine, i will try and remember the site where i got them...

i will be taking mine out soon tho, the gap is too big.

[Pva_Glue]

ok How often do you have to change spark PLUGS???

and also I have NA so is that mean the GAP will be different as well from Turbo cars?

cheers

Joe

[hitnrun]

Guys from my understanding and talking to the fools at the local auto shops, I though that the platinum plugs were better than the iridium plugs, and that the iridiums were marketed for dunnydores that wanted better than copper, but couldn't afford a better car or plugs??

So I guess the question is, which is better, which is more expensive and which is better in a turbo skyline?

maybe we could have some suggestions from users of both, that might help the rest of us when paying for $20 plugs

(At least we don't have to get "performance leads" ahahahahaha)

[adam 32]

ive heard NGK coppers are fine you just have to change them more often (10-15000 k's) especially if ur running rich... cant remember the part # but one come in 0.8mm gap theyre the ones il be gettin in a week or so

[PranK]

hitnrun,

I looked into it also, some boring nights at work i tell ya.

The iridiums are NGK's better plug, but they only come with a fat gap (1.1mm)... thats where I am having problems with it missing at the moment.

The iridiums rrp is ~$21 and the platinums are ~$18... but, i'll be going back to copper with a 0.6mm gap.

The iridiums were fantastic when new, the car idled better and was different when cold, but now they are just **** (well, i hope its the plugs causing the problem)...

Anyway, not very informative, but thats me!

Christian

[Blitz]

Christian: actually that might not be right.... john P mentioned last week when i tried to order HKS plugs for my car that iridiums now come in a 0.7mm gapped unit.

I was going to use 0.8mm gapped iridium plugs.

[Clint32]

I think you can get the iridiums in different gaps, have then in my car with a smaller gap and no probs running 15psi.

[PranK]

oh ok, i think they may used to have come only in a big gap.

oh well, nevertheless, i am returning ot copper.

[whatsisname]

NGK Iridium’s / Platinum’s / Copper’s

I've tried the odd plug in the near on 3yrs of GTS25t ownership & after being told by a few different local suppliers of NGK plugs that they didn't have a 7 heat range iridium to suit my application I decided to settle on VX's, which have been bloody excellent to date!.

Why 7's you ask? Well, as per the NGK US site, it’s recommended that for every 75 to 100hp (fly) above stock you go 1 heat range colder. So take the RB25DET from 250hp to 400+hp & it's a good idea to go to a colder plug, hence I now run 7's. Read this info - http://www.ngkspark.com.au/spark_plug_tech_tips.htm

So for those that wish to use iridium plugs but want a 7 or colder plug what do we do? Luckily NGK have a racing application plug labeled IRIWAY, i.e. IRIWAY7, IRIWAY8 & so on depending on the required heat range. These plugs aren’t likely to be stocked on the shelf so you’ll need to request them via special order. They cost ~$25ea.

There’s no problem with using copper, platinum or iridium plugs so long as you replace them as required. Naturally the better quality materials mean the plug will last longer (copper will wear quicker) but as long as the spark is strong enough to ignite the mixture, & most importantly the plug is the correct heat range for the application, then all is well. : )

I'll be giving the IRIWAY7’s a shot next time I do a plug change.

On a final note, I recall a test done in an old issue of FF&R’s where they tested a range of different plugs on the same car/dyno etc… The humble old coppers made the most power! Cheapest plug for the biggest power gain. Mind you power isn’t the only aim of a good plug.

My 2.2c

[hitnrun]

Thanks everyone for your replies.

Most interesting.

Well I think I might just stay with the platinums for now, and try the iridiums next time.

Cheers,

Tim

[Guest Boxhead]

platinum plugs are the only way to go.