Spark plug gap dilema.. 1.1mm or 0.8mm

[Duncan]

rather than decreasing the gap in your spark, it'd be wiser to increase the power of the spark innit? wire up a set of quick charge capacitors to your sparks and bob's yer uncle...

absolutely, you want the biggest gap you can...check out the big hp turbo cars they all have significantly upgraded ignition system so that the spark doesnt blow out. gapping down is just a stop gap measure

[Ronin 09]

gapping down is just a stop gap measure

nice pun!

I started at 1.1mm then gapped down until it stopped misfiring

[Fazt_R33]

does anyone have the part number for the 0.8mm sparkies? i was told by repco that the BCPR6ES are not going to fit the skyline and should get some other sparks for like 500% more....

anyhelp?

[Elithrar]

Coppers are fine; the Repco guys just want to make more money off you. Coppers are cheap enough that changing them every 5000kms isn't too much of an issue.

BCPR6ES-11's, gapped to the appropriate space will do fine. Heck, check the NGK website; whilst they recommend the platinum or iridium, you can see that the plug for the copper/(iridium) is a BCPR6ES(IX)-11. Same plug, just won't last as long, but can work out cheaper.

[sky30]

I get the NGK plugs with out the resistor BCP6ES, theses come already gapped to .8mm and fit skylines, and VL commodores. I used to run the NGK-(with resistor) in a VL turbo, any thing over 15 psi and the resistor caused them to break down, swapped them to non-resistor and had no problems runnnning 21psi.

[Nozila]

ive put chep bosch plugs in my sr20 and it runs fine, no missfire at all - pre-gapped at 1.1mm. Although i havent checked the gapping on the line yet as the sparkies are a pain to get too. On the top of my head, i can recall that in the service manuals of the line/180sx, it states that 1.1mm is the standard gap.

[Leadfoot]

If you think about it the Iridium plugs may actually be best value for money.

Iridum plugs should at least outlast 5 sets of coppers, and on that basis alone they are around the same total cost.

Then, when you factor in the time taken to change a set of plugs, at least half an hour if your being careful not to strip the threads and remove all the coil packs and wiring harnesses, the irridium plugs make a whole lot of sense. Especially if you value your time at around $50/hr.

As an added bonus irridium plugs give an extra 5 to 10 hp gain on the dyno. This is apparently something to do with being able to run a bigger gap due to the much sharper point of the iridium electrode.

[blind_elk]

I stuck a set of Iridiums in my RB25DET, left the gap standard (1.1mm). I'm more than impressed - car starts easier, and has not had a misfire, running 10psi and producing 180 Awkw.

If you want to keep pulling the engine apart every 6 months to change plugs, then fit coppers, otherwise fit Platinums or Iridiums.

[RT33]

Friends S1 r33 was missing real bad at the end of 2nd, 3rd and 4th. The only mods he has is a cat back and a bov. I repalaced the plugs which were gapped at 1.1 to .8 He was so happy that the car was finaly running smoothly and said there was more power in every gear.

[nmcmahon83]

RT33 i'd say that's because the coils are rooted, and lowering the gap means the coils can do the half arsed job they were designed to... i bet if he upgraded to split fires and ran the 1.1 gap he would be even happier...

I have the same problem...

[RT33]

nmcmaho83 i cheched the coils for cracks because i had a similar problem last year, but i was running 10psi. You could be right but its running alot better than it was, so everyones happy.

[nmcmahon83]

Yea, my coils are on there way as we speak... so no more missing for me soon.

[Fazt_R33]

so what is the definete code for the PreGapped 8mm sparkies? and does the code vary with or without the resistor?

cheers

[sky30]

.8mm NGK with resistor- BCPR6ES

.8mm NGK non resistor- BCP6ES

[superspit]

what proof do you have of this? i find that very hard to believe...

if it wasn't missing on stock boost with 1.1mm then don't change it! i now run 1.1mm gap with 12psi of boost on my rb20 and have no issues at all. maybe its an rb25 thing?

aahh yes.

the proof really is in the pudding! :wassup:

[blind_elk]

so what is the definete code for the PreGapped 8mm sparkies? and does the code vary with or without the resistor?

cheers

Depends which engine you're fitting them to.

As sky30 showed, the non-resistor plugs don't have the "R" in the code.

And the (pre-)gap(ped) size is tacked on the end eg BCPR6ES-11 = 1.1 mm gap, BCPR6ES-8 = 0.8mm gap

[lwells]

So is there any reason too get the resistor type?

Out of interest, is there somewhere that keeps stock of the BCPR6ES-11 (or minus the resistor) in Sydney. All the local places I have been too only stock bommodore and other common car types.

LW.

[Jax]

Those who said don't reduce gap, are right. Only 2 things make engine go, Fuel and Combustion [ Spark]. If you make fuel side better [no matter how] it is counterproductive to make fire smaller - which reducing gap does - Upgrade ignition to at least keep up with mods to fuel side. Factory recommends 1.1 / 1.2 for just about all models, don't go below that. Just put set in R32 GTSt @110000klm NGKs PFR6A-11, same as those that came out, which still appear perfect,inc gaps. The 11 on the end of the number on NGKs indicates 1.1 - 12 would be 1.2, 9 would be 0.9, etc.

[superspit]

Those who said don't reduce gap, are right. Only 2 things make engine go, Fuel and Combustion [ Spark]. If you make fuel side better [no matter how] it is counterproductive to make fire smaller - which reducing gap does -  Upgrade ignition to at least keep up with mods to fuel side. Factory recommends 1.1 / 1.2 for just about all models, don't go below that. Just put set in R32 GTSt @110000klm   NGKs  PFR6A-11, same as those that came out, which still appear perfect,inc gaps. The 11 on the end of the number on NGKs indicates 1.1 - 12 would be 1.2, 9 would be 0.9, etc.

Man, with logic like that, we'd all have to agree with you!!

But, practicality often rules out there.

After slightly raising boost (whatever way you choose to do it).......

You could go Splitfires $700-$900 (to allow larger gapping of plugs and consistent arc travel.)

Or...10mm socket tool and 30 mins of your time to decrease plug gap so arc doesn't 'blow-out' (like a candle in the wind).

Let me see,,.....when I get more money...I'll go the splits....'til then, I'll re-gap!!

Bet you'll find it hard in a daily driver to tell the difference!!

Anyways.......

Superspit Mark.

[Jax]

Yeah -- Know about practicality...............Pity you live so far away from me, you could do mine next time, I can't get even close to that 1/2 hour. Jeeeeszuss, that would be worth watching.