Hi people,

 

Ok, I have just purchased some NGK BKR7EIX-2667 plugs. These are the colder rated plugs that I need, due to all my engine upgrades, as I am getting det over 14psi on the ol' tubs.

 

I just need to know what is the best gap to set these little puppies to....... Been advised on 0.6mm. Is this correct?

 

Cheerz people,

 

Alz.

Seems a small gap that Alan, I have some heat 8's to go in and the opinion I have got back is not to gap them as low as that :huh:

Hi Alan,

 

I'm no expert mate - but I thought that platinum plugs always came pre-gapped; so you don't have to do anything..... But I'm sure someone will correct me if I'm wrong!

 

Richard:cool3:

stock are 1.1mm and cooler plugs should be 0.8mm :)

 

As Richard said, should be pre gapped. mine where.

Cheers for the info guys.........

 

0.8mm seems to be the norm for colder plugs, as you say Dave (after trawling the interweb....), but I do not trust the "pre-gapped" setting. I will set these puppies (and I do like puppies.....) to 0.8mm and let you know the findings.....

 

Thanks again puppies.... lol, I mean people....

 

Alz.

you will proberly find they will be gapped to 0.8 anyway once you test them.

 

I have heard that platinum or iridium tips are very easy to mark when gapping them so be carefull :)

unless I'm mistaken, if the spark's blowing out, you'll get misfire, not det ...

 

the plugs won't do any harm, but you sure you're fixing the right problem?

The spark is not blowing out, just getting det over 14 psi. The plugs may not cure the problem, just trying to rule most things out, and I haven't changed the plugs for a long long time.

 

Alz

It's unlikely that changing the heat range by 1 grade will stop det. I'd check my base ign timing first and fuel pressure if not ign.

 

Standard gap for an unmodified Z32 is 1.1mm. Upgrades may make the engine run hotter in which case a colder plug will allow heat conduction away from the firing end to be more efficient, keeping the tip cool and reducing the likelihood of pre ignition and/or detonation (a hot tip can become a source of ignition). A smaller gap is sometimes needed when flowing more air (i.e. increasing boost) or increasing compression ratio, it's not so much blowing the spark out but the denser charge in the combustion chamber logically has a similar effect to increasing the gap (there's more air between the electrodes, albeit compressed). These are two seperate issues.

 

You need to keep as big a gap as the ignition system will comfortably support throughout the rev and boost range otherwise efficiency (and performance) will suffer, mainly at low revs. Mine is running quite happily on BKR7EIX-11 and putting out around 450BHP at 20 psi, no hint of misfire or det on a 1.1mm gap but tbh I've not found a long/straight enough road to nail it yet...

 

Cheers

H

Makes a Massive differance Rob if your running higher boost.

Heat range shouldn't make a 'massive' difference unless there are other systems functioning incorrectly. It may make enough of a difference to an engine/setup that is borderline for detonation or cold fouling but a single heat range will only make a minor difference to a correctly set up engine. The point I'm trying to make is that a spark plug won't prevent det due to other (more likely) causes, but it might cause it if the heat range and/or tip configuration are completely incorrect.

 

Cheers

H

 

 

Cheers

H

Yeah the gapping must also be correct.

 

Mine was detting and popping like a pig anytime when i went near any boost. but i have a stage 2 chip in with bigger injectors etc. As soon as i went to correct gap and a cooler plug it was like a new car and never missed a beat since. My mpg also went from about 9/12mpg to an average 21/24mpg.

 

So in my case it made a massive differance

Also bear in mind that new plugs will normally make a big difference in any event, providing they're suitable of course and depending on how worn out the old plugs were. A plug usually reaches it's wear limit through erosion of the electrodes, this increases the gap beyond the acceptable limit and misfire will ensue, closing the gap up weakens the ground electrode (bad!) and puts the electrodes out of true and therefore is not recommended.

 

Popping and misfiring is often due to a hairline fracture of the ceramic insulator. I'm still a little cynical that the difference was due purely to choice of plug Car.Mad. The amount of gubbins that needs to be removed/disconnected, coil connectors, balance bar etc to change the plugs means there are a lot of re-made connections and the condition of your old plugs may have been part of the issue. Intermittent firing will cause thermal issues in the affected combustion chamber, this can lead to det.

 

I first installed a set of Iridium plugs in my Z about 10 years ago, the difference was amazing but subsequently I came to the conclusion that the original plugs were incorrect (they weren't even a matching set!!) and were somewhat worn - hence the transformation. Having said that I do think Iridium plugs offer a significant improvement where there is a suitable Iridium equivalent to the OE plugs, equivalents for the NA are fine but a bit iffy for the TT. I will also say that I used BKR7EIX for a couple of years with no obvious issues related to the plugs. I did used to get some det but it seems it was related more to engine condition than anything else.

 

Digressed somewhat! Anyway, point is, check the obvious and most likely stuff first, imho ignition timing is the #1 cause of det and can slip for no apparent reason - I know from experience :(

mine were new plugs well about a month old. when i did all the mods together and they were just running to hot looking at the tips. there in another zed now and working fine.

 

I had sut all over the back of the car and when i tried to boost i could see it spitting out the sut etc. all it came down to is the plugs.

Well............. I have checked my timing and it is bang on 15dtdc, I have a new fuel reg and damp, new fuel filter, new walbro fuel pump, 550cc injectors are working fine, new splitfire coilpacks, new injector and coilpack connectors with a/c spec splices.........

 

Got the new plugs fitted now, just need to give the ol' girl a blast to see if the dredded det is still lurking around.......

 

Will post up in a few days.

 

Alz.

Edited March 13, 201213 yr by AlanZ

Very bad expensive problem If you are getting det at over 14psi I WOULD BE LOOKING AT YOUR FUEL MAP and timing [ running lean ect.] try fitting a NIStune ECU first then A EXPERT DYNO TUNE [saves engine pistons]or set the boost back to about 10psi.

The plugs I use are internal electrode type Bosch platium you cannot set the gap on these plugs never had a plug give up or fail.