I'm taking out my old Iridium plugs and going to fit the above listed in the title.

 

Running 14PSi. NGK doesn't list this plug under the 300zx however does anyone know what gap setting I need for these particular plugs? I believe it's 0.36 however my feeler gauges are at 0.4 (stock being 0.44). Is this suitable or do I need a slightly reduced gap? I'll have to buy another feeler gauge as my one does not have this measurement.

Ah! Found the 0.05! Gapping them down to 0.35. Can someone who knows confirm?

 

Thanks. :)

I belive mine are gapped at 0.7 mm. What you are proposing seems far too close.

Standard gap is 0.45, 0.7 seems huge personally. I beg to be proved otherwise though.

Tell a lie, ungapped they're 0.7.

Simon you’re getting your metric and imperial mixed up. The 0.36 figure you have in mind is probably the stock TT gap of 0.036”.

I’m suprised your not keeping stock plugs and they are gapped at 1.1mm, that’s what the 11 bit in the name is for.

Simon you’re getting your metric and imperial mixed up. The 0.36 figure you have in mind is probably the stock TT gap of 0.036”.

 

I omitted a zero.

Si, why you going for Grade 8’s.... you only need grade 6’s at your spec. I didn’t have any problems with grade 6’s until 17/18psi

The stock spark plugs are NGK PRF yadda yadda-11 the 11 refers to the gap which is 1.1mm.

Edited May 6, 20187 yr by Stephen
Adding picture

I'm taking out my old Iridium plugs and going to fit the above listed in the title.

 

Running 14PSi. NGK doesn't list this plug under the 300zx however does anyone know what gap setting I need for these particular plugs? I believe it's 0.36 however my feeler gauges are at 0.4 (stock being 0.44). Is this suitable or do I need a slightly reduced gap? I'll have to buy another feeler gauge as my one does not have this measurement.

 

I am intrigued why your going for a cheap non platinum plug which fit the Fiesta turbo rather than the specific NGK platinum item?

 

On the upside taking out the hateful iridium plugs is a great leap forward, never designed for the z engine, work best with 2.0 litre and under high revving engine`s, this born out by the many issues with these plugs we saw in the workshop and confirmed by the HKS Denso agent at the B.ham Auto sports show one year ! when you hear a zed engine running at tick over with them fitted you can hear the different tone in the engine, poor self cleaning on non high revving engine.

 

Jeff

Edited May 6, 20187 yr by JeffTT

Thanks all. I'm getting conflicting information from somewhere. There are always arguments for and against the iridium plugs, but it did run a lot better with the previous NGK plugs in it.

 

So the 6s and the 7s are the best for a mild boost upgrade? Pretty sure I ran 6s before and Jeff, as you say, it idled better.

I think a lot of the information on spark plugs was clouded over by the extreme tuning lead by Noel. On paper everything he says made sense but in the real world, it would be nice to have some more conservative data from folk experienced with tuning these cars. For example, at what point do we need to migrate away from the stock PFR plugs as, seemingly the advice is always to use these if your setup allows as they will make the car run smoother.

 

I would rather my idle was smoother and I have plugs recommended by the US tuner Greg Dupree. These are NGK iridium BKR7EIX but if there is an alternate out there that smooths out the idle I’d be all over it assuming it doesn’t compromise performance at WOT.

 

Simon’s thread is covertly changing to a “what spark plugs” thread and I like it, I don’t believe we’ve had this discussion for a while.

Agreed, it would be good to have another debate, I'm keen to hear more as yes, it was clouded by a certain person.

Dunno what's wrong with me at the moment! Turns out I have BKR7E in at the moment. Are the 'IX' a different varient?

I purchased the PRF6B-11 I think they are about 5 years ago. They weren’t cheap however from what I understand NGK worked with Nissan to design the plug. This was about the spark placement in the head bowl particularly. I believe the US cars received grade 7, these are no longer available so they’ve subsequently changed to our spec the 6. Feel free to correct my memory here.

 

Because of the cost Noel was running a copper plug, those BK whatever’s. These didn’t correctly place the spark, I believe it left them slightly shrouded. But they were a cheap off the shelf compromise. He felt the compromise was acceptable in reflection of cost and they could be gapped where as the stock plugs don’t like this treatment.

 

In summary the stock plugs whilst expensive and uncommon last 10s of 1000s of miles and for the vast majority will be the right part. If you starting to experience spark blow I’d really hope this is encountered with a professional edge and that can be addressed in due corse.

I know things didn’t work out with Noel but this club has no one now who is a member to explore things. For example does anyone on here have Nistune and actually have half an idea how to use it?

Greg @ Protuner has some more qualified and reliable info as he's tuned a lot with Nistune. Joel suggestion are what I believe he suggests.

Oh I’ve heard good things about Greg that’s not my point, my point was on a membership level.

Sure, appreciate that. He'd be a good guy to have on as a trader.

I've used the noel plugs, the BR8ES (I think) for 30'000 miles and I've put about 6 sets in. They have been fine for me. I always forget the gap and so have to measure the ones I remove and make sure the ones going in are the same.

 

I think, it's about 0.8mm I don't think the gap is as much as the 1.1 mentioned above.

 

I only want whats best for my car, but like all these things, there are so many conflicting oppinions. Playing it safe, I know these work for my set up. So I've stuck with them.

 

Open minded to change though.

I would rather my idle was smoother and I have plugs recommended by the US tuner Greg Dupree. These are NGK iridium BKR7EIX but if there is an alternate out there that smooths out the idle I’d be all over it assuming it doesn’t compromise performance at WOT.

 

BKR7EIX-11 are the ones I run, no problems with them.

 

https://specialtyz.com/shop/ngk-iridium-ix-spark-plugs.html

http://www.ngksparkplugs.com/about-ngk/tech-talk/spark-plug-basics

 

I just read that and know a lot more about plug heat ranges. It maes perfect sense and I should have read and learned it years ago.

 

The number and heat range is linked to the physical dimensions of the plug and how heat soaked it gets.

 

This has to match your engine and driving style to keep any plug in it's sweet spot. Under drive a plug and cause it to be too cold and it will soot up. Over work one, it will become too hot and you will cause knock and det and stuff.

 

So hot plugs get hot easilly but self clean well. Cold ones take more to overheat.

 

If you pootle about with cold (big number) plugs, they will soot up. However, if you nail it around at 7000rpm with hot small number plugs they will overheat. So... pick your heat range and drive accordingly. I have to rev my 8 grade plugs or they will soot up.

 

It all makes sense :)

Edited May 6, 20187 yr by tomfromthenorth

Just checked my spec list and i used to have NGK BKR8EIX with a 0.8mm Gap, Lee Dent swapped them out for NGK BKR7E, i just went with it - with no noticeable difference.

I may go to 7s then. My car always drives well fast but can sometimes be a bit less refined if driven slowly for too long. 7s may be the compromise to go for.

 

Shouldn't the gap be as big as you can get away with. And as I understand it spark "blow out" (I know it's not being blown out but it happens because the boost is putting too many air molecules in the way of the spark between the electrodes) is just a soft stumble???

http://www.ngksparkplugs.com/about-ngk/tech-talk/spark-plug-basics

 

I just read that and know a lot more about plug heat ranges. It maes perfect sense and I should have read and learned it years ago.

 

The number and heat range is linked to the physical dimensions of the plug and how heat soaked it gets.

 

This has to match your engine and driving style to keep any plug in it's sweet spot. Under drive a plug and cause it to be too cold and it will soot up. Over work one, it will become too hot and you will cause knock and det and stuff.

 

So hot plugs get hot easilly but self clean well. Cold ones take more to overheat.

 

If you pootle about with cold (big number) plugs, they will soot up. However, if you nail it around at 7000rpm with hot small number plugs they will overheat. So... pick your heat range and drive accordingly. I have to rev my 8 grade plugs or they will soot up.

 

It all makes sense :)

 

Bang on the money. The colder the grade the more recessed the electrode is into the plug, but as you mention there is a trade off. Because the electrode is more recessed, it doesn’t create as clean a burn at idle, low load and low RPM, but risks over heating or blow out at high rpm/high boost scenarios.

 

From memory, I started experiencing spark blow out issues at around 18psi on 6’s and 23psi on 7’s.

 

The other thing to consider with EIX’s (iridiums), the tips CANT be cleaned. Once they’re fouled, they’re junk. Coolers on the other hand can be. Yes, iridiums last longer but I can get a set of grade 8 NGK coppers for £11 delivered, unlike £60 for iridiums.