Spark Plugs

[antonirabic]

hey, i need to replace the spark plugs in my r33, and just want to know how many .mm it needs to be

cheers

[QWK32]

i'm assuming you mean what gap to use, and 0.8mm gap is a good starting point.

[antonirabic]

ye the gap 0.8mm cheers man

[RusH_]

Have a quick search, 0.8mm isnt really necessary unless running higher than stock boost or if your coil packs are on the way out where the 1.1mm gaps werent giving you a good enough spark due to it being blown out by higher boost etc, if you car is relatively stock to mildly modded you shouldnt require 0.8mm.

1.1mm should be fine but the choice is yours

Steve

[GeeTR]

^ agreed

The idea's to try and use the largest gap possible, with the ignition system one is using. One might be able to run 1.1 now.. .then need to gap to .8 in another +100rwkw time, then back to 1.1 with some CDI / some ignition amp.

[tridentt150v]

not wanting to hijack a thread, but what diff does splitfire coils make?

Has anyone tried widening their gap again after installing them?? Logic says that if they are better than std coils, then you don't have to close the gap, it can be reset to say 1.1mm.

[Wacky Dee]

took my car (r34 gtt) for a service recently incl. spark plugs changed. My car has only only light mods (exhaust and 11psi boost) and it's tuned and not missfiring. However the mechanic insisted the new spark plugs should be 0.75 gap even though my tuner said since the car is not missfiring any new spark plugs shouldn;t be gapped. Any harm in having new spark plugs with a smaller gap anyway ??

[tridentt150v]

No, but I wouldn't go below 0.7mm, try 0.8mm.

Its only for cars running more boost anyway, say +12 psi. if your not running more boost don't do it.

There is a balancing act between boost 'blowing the spark out' and the gap being large enough to provide a healthy enough spark to completely ignite the fuel.

[GeeTR]

took my car (r34 gtt) for a service recently incl. spark plugs changed. My car has only only light mods (exhaust and 11psi boost) and it's tuned and not missfiring. However the mechanic insisted the new spark plugs should be 0.75 gap even though my tuner said since the car is not missfiring any new spark plugs shouldn;t be gapped. Any harm in having new spark plugs with a smaller gap anyway ??

As mentioned, theres no harm, just less power. Exposing the volatile chamber mix to the strongest lick of plasma possible, prevents chamber velocity from effecting it, as well as having the greatest chance of complete charge combustion.

SplitFire allowing larger gap? Not that I've seen... They are simply cheaper then OEM coils... and blue.. so homos buy them. Serious contenders use Twinspark or proper step up amplification

[tridentt150v]

Back atcha, you have a HKS amplifier, or an MSD system. Can you increase the gap back to say std?? Or are you forever limited to the murky depths of 0.8mm.

[btw I agree with you on the splitfire, any perceived improvement in spark is still insufficient to increase gap].

[Wacky Dee]

so using gapped spark plugs can actually result in less power ????

[tridentt150v]

No, all spark plugs have a gap, the energy then jumps across this gap as a spark.

[Wacky Dee]

ah .. I think I get what GeeeTR meant now .. 'smaller gap' results in less power (from the ignition coils) needed for the spark to jump accross the gap. I read it as 'smaller gap = less engine power' lol

Edited July 31, 2008 by Delta Force

[GeeTR]

ah .. I think I get what GeeeTR meant now .. 'smaller gap' results in less power (from the ignition coils) needed for the spark to jump across the gap. I read it as 'smaller gap = less engine power' lol

Chuckles, you read correct the first time but power loss is relative. I was trying to get at a stronger spark getting a little more combustion pressure out of bad (rich/lean) mixtures and rough condition (lots of boost or rpm or N02 or WI)

Ppl saw CDI or other cool multi spark per cycle setups really in big camed, holley'd street V8's first, as large valved heads aren't conducive to good low rpm combustion efficiency, coupled with the afore mentioned generously jetted 4 barrels.

Think of all the twin plug per cyl industrial motors, alfa's, aeroplane's etc. There must be a reason other then maintenance durability me thinks.

Guess you could try tappin some plugs to .10mm and go for a drive

I think the gist of the thread is that, most RB's out there should be able to run .80+ minimum, if not theres a sad ignition component somewhere.

Edited July 31, 2008 by GeeTR