Which Spark Plugs for R33 GTS25t with mods???

[GiJOr33]

Hi,

I've done a search on the topic, but as my car isn't really stock ad i don't really know much about the difference in plugs (cool, hot, the gaps etc) so i thought i'd post asking what plugs i should go with for my 94 R33 GTS25t.

My current mods stand at:

ARC FMIC

Injectors

Fuel pump

HKS GT3040 Turbo

Exhaust Manifold

Full 3" exhaust

Oil Catch Can

OS Giken Twin Plate Clutch

HKS FCONV

HKS PFC-FCON

HKS VPC

Greddy Profec B Boost Controller

I'm looking at running 18-25psi once i find someone to tune my car in Melbourne (and depending what is safe), so i'm not sure what spark plugs i should get. I'm not too worried about the price, I don't really want to go ordering HKS plugs from Japan!

Any ideas on what i should get?

Also what engine oil? and should i use one of those Oil Drain additives when i change it?

Thanks

Andrew

[whatsisname]

Plugs - I'd run at least a 7 heat range (I do) & gap them to 0.8-0.9mm. If you had an upgraded ignition system then it'd be far better to keep the gap @1.0-1.1mm.

The NGK "Iriway" 7's are a good choice. "Iriways" are one of NGK's Iridium high heat range, special order in most cases (~$30ea) If that's too expensive then I'd go for Platinum in a 7 heat range (~$16-18ea).

If you don't mind changing plugs regularly then just use BCP7ES, if they do a 7 in the BCP range?

Most of the HKS, Trust type plugs are just the same as the NGK Iriways (but closer to $40-45ea!).

Edit:

Oils - Motul (300V) or Redline are both excellent oils.

[GTS-t VSPEC]

GiJOr33,

I agree with whatisname, go for either platinum or Iridium plugs from NGK, I gap mine down to 0.7mm because otherwise you'll get breakdown at high boost.

The redline stuff is very good, but for the price I'd still use Mobil 1 unless your racing the car. Change oil and filter more regularly if your treating the car harshly.

See'ya:burnout:

[Merli]

I use NGK Platinum 8s, gapped at 0.8mm.

[GiJOr33]

Cool... thanks for the tips guys. I think i'll go Mobil 1 oil, and the Iriways from NGK.

What is the difference in heat range? what does it mean? And how come you picked 8s over 7s Merli? and is 8 hotter or colder than 7?

thanks again

Andrew

[Zahos]

8's are cooler

for big boost, 7 and 8 are both good, but with aftermarket managent, and bigger injectors I'd lean towards 8

coppers, Iriways, platinum all perform the same, but coppers dont last as long. I'd go the coppers anyhow as replacing spark plugs is better than cleaning (as you would with the more expensive at certain intervals)

Dont know if coppers come in 8's but a good choice in 7's is NGK BCPR7E. If there is a BCPR8E, then go for that...

my 2 cents

Zahos

[benm]

18-25 PSI of boost ???

:crazy:

Geeeeezus I get scared on stock boost when im getting up it let alone when i flick the switch to 12psi and here u are about to run double.

[whatsisname]

I can't remember the exact rule of thumb? But it's something like for every 75hp increase go one heat range cooler than standard.

1 - hot

|

10- cold

A stock R33 RB25DET is ~250hp & runs a 5 heat range plug

325hp - 6's

400 - 7's

475 - 8's

& so on...

Going too cold for your engine requirements can cause fouling @ idle & cold starts. If the plug tip temp is too low it'll foul very easily.

I figure my engine is somewhere ~400+hp hence I use 7's.

EDIT: - Just checked the US NGK site. They recommend 1 heat range cooler for every 75-100hp increase over stock.

[Merli]

Pretty much everything in this thread is correct...

Glad to see the performance-oriented guys helping each other out on this forum :uh-huh:

benm: 192rwkw from a stock turbo is excellent! well done, time for a turbo upgrade to bump yourself into the 200s!

[Leewah]

hehehe. I'm running copper plugs gapped at 1.1mm and running 18psi

Now that my CDI is in......Boost here I come!!!! :burnout:

[GTS-t VSPEC]

With 18-25psi of boost I hope you have some forged internals, I'm pretty sure the factory pistons will not like this boost. The GT30 should start producing real power arond 18-22psi, so it should easily get some big power.

See'ya:burnout:

[predator]

My car is running pretty well - but will reducing the plug gap to 0.8mm give any improvements? I'd say they are currently gapped to around 1.05mm but i haven't pulled them out to check.

Actually, how do i even get to the spark plugs? Do i have to remove anything? Are they just between the injectors there or do i have to remove the top case?

[rev210]

7 or 8's have some 9/10's for the races (change them at the meet).

[GTS-t VSPEC]

At stock boost then the 1mm gap is ok, but as you increase the boost then the gap needs to be decreased, unless you run a CDI.

To get to the spark-plug you will need to remove the cover off the top of the engine, which usually means taking the intake pipe to the plenum off, then with an allan key you take the coil-packs off and the injectors are sitting down in the block. You will need a long socket to remove the plugs.

You can easily regap the plugs with a set of feeler gauges.

See'ya:burnout:

[predator]

Thanks for the help vspec...

Riddle me this though: why is it every time though i go to play around with my car is it like 35 degrees in melbourne !?? grrr

[GiJOr33]

so it doesn't matter if i run copper/platinum/iridium, as long as it's a 7 plug?

what's a CDI worth these days leewah?

I do have a shit cold start at the moment as the car needs a tune (got HKS gear... no one in melbourne to tune it!). So i'll get new plugs to go in once it's tuned

[GiJOr33]

Oooo... also what oil/fuel filter do i need?

I'm doing the full buy up for the next maintenance effort!

[skyline33]

I have a set of brand new hks spark plug if you're intrested

[GiJOr33]

for how much??

[GTS-t VSPEC]

I think that the HKS plugs are a waste of good money, they are good for one day of circuit racing then after that I would throw them away. The number of times my tuner has pulled out f#cked plugs and they are the expensive HKS ones.

Predator666,

I think that is Murphy's law, you mustn't work on your car much as it doesn't get to 35 often in Melbourne.

See'ya :burnout: