Which spark plugs are really the best?

[TME_Steve]

OK so my car is relatively well known but in summary it has some mods and runs up to 18psi at low rpm and about 15psi at 6000, makes 210kW at the hubs from 4500RPM to 6000RPM.

When I bought it it had BKR6EIX plugs in it and when the boost went up beyond 14-15 it started missing. So in went a set of colder BKR7EIX plugs along with coil pack clean and dielectric grease everywhere, which was all great! For a while....

Then about 6 weeks ago it started missing above 17psi, figuring the plugs were on their way out and I really could do with a COP setup or better leads I simply wound the boost back to 16.5 and happy days.... For about a week....

Back to 15.5 and again good for a week or two. now it misses over 14 and starts first go but runs like crap for a few secs when it's cold (below 10 overnight) so my plugs are pharked and we are talking 15000km and 3 - 4 months old!

Oh and both sets were gapped to 0.8mm

I know mine runs more boost than most but it mostly cruises at 2700RPM on a freeway so it's not a hard life for it.

So this got me thinking, are these iridiums the best thing? Talking to some evo and skyline guys they all say no, stick with copper and change regularly (nice to have easy to get to plugs). So last night I trawled through manufacturer sites and forums and see that again most of the evo and skyline guys use copper plugs and change them along with the oil. I also see there are a higher performance IRI series iridium for modded cars and an EIX-P series that are meant to last longer.

So I figured I'll grab the cheap arse BKR7ES copper plugs and see how they go. I could only easily get 1.1mm pregapped so I'll re gap them to 0.8 first. If the manufacturers literature is not embellishing the benfits of iridium, these should be crap straight away and I'll be pulling them back out rather quickly. They should also only last about 3 weeks. However if I get 10000km out of these then I know what I'll keep using given that the iridiums only lasted 15000....

If they are rubbish and I have to change them before 10000km then I'll give the IRIWAY7 plugs a go. I have seen people talk about these but has anyone used them yet?

Yes I know I can change the leads to NGK as well but I want to keep results consistent so I know what change did what.

 

[twisted32]

I hear your pain Steve, and as you know mine runs very similar to yours (17psi, 200awkw), and I have had my share of plug caused missing issues. Although I do run the ICE ignition leads (each lead resistance is less than 2kohms from memory) since the first set of iridiums went in ( 22k ago now), here is a break down of my spark plug records:
BKR7EIX-11(could not get 0.8mm and did not want to re-gap iridiums) lasted for 11k (of note this included a 5k trip to the gold coast and back) with boost set just under boost cut (14-14.5) until that annoying miss reared it's head on my initial tune attempt at SKR. Steve said it was the plugs, and put in a set of BKR7ES (0.8mm) to make sure. These worked well, but lasted less than 5k when the miss once again became evident during the first successfull ECU flash at SKR (17psi and 200awkw). I chased coils (changing one at a time), and problem was solved when I installed the current set of BKR7EIX (0.8mm) iridiums. So far these have done just over 6k and have had no issues so far. It will be interesting to see how long these ones last.
Maybe go back to platinums?

 

[Lateralus45]

Sounds interesting. Will be watching out for the results.

 

[unclepaulie]

in my ownership timeline of my galant, i hav changed the plugs 2 times over the 40,000k's i hav owned it.

1. changed to stock to iridium 7's, .8mm. these lasted about 10,000km's. upon failure, they were severely over burnt and the gap had blown out to about 1.2mm. dodgey coilpacks maybe hav been a contributing factor.

2. removed iridium 7's, put copper 6's in the front and iridium 6's in the rear, both gapped to .711mm. the ididiums in the rear have lasted a good 20,000km and the coppers i change every ten thou. not sure if they hav started to degrade by 10thousand, but its a peace of mind thing. Oh, and that is at 15psi daily with a new set of coilpacks and leads and dielectric grease

 

[Guest]

Have been recommended HKS plugs when running higher boost by EVO owners but have no personal experience. Personally running NGK iridiums (6's I think from memory) gapped at 0.8 for 30,00km with no problems - boost set around the 15psi mark although has run higher (17) with no missing problems. Also have ICE leads and serviced coil packs and a flash tune from Merlin.

Looking at changing lifters soon so will also change plugs whilst I'm there - has anyone tried the HKS plugs?

http://cgi.ebay.com.au/HKS-SUPER-FI...=AU_Car_Parts_Accessories&hash=item1e60651f82

 

[naughtika]

how about denso plugs? from denso catalogue it says that VK22 is our alternative for the BKR7EIX

or VK20 for the BKR6EIX

I'm gonna order about 3 sets.. anyone else want some?

 

[TTVR4]

i just got a set of IRIWAY 7,
i will be fitting them in the next two weeks, hope they do the job at $20 a shot

 

[AKKO]

Yes I know I can change the leads to NGK as well but I want to keep results consistent so I know what change did what.

I'll also be watching this with interest as I've just bought a set of NGK leads so next step after that may well be new plugs to match...

 

[TME_Steve]

Ok then maybe a slight change of plans, I'll put copper 7's in this time, assuming they last 5k that will be about 6-8 weeks for me, if they last 10k then double that. Once they are stuffed I'll try a set of copper 6's and see if they work.

Given it had iridium 6's in it from when ET owned it and I did another 25-30k in it before they gave up, if they can deal with the boost they may be the way to go, I'll know that from trying copper 6's, plus Paul's experience sounds promising.... If the copper 6's are no good, the IRIWAY7 will be my next step and by then we should have a coil on plug setup sorted out for the rear plugs as well. I'd like to try Denso's also but this will be a 3 year experiment if I try everything and by the end of the next few sets I'd really like to have COP sorted.

Rob - your experience mirrors mine....

Tim - how long have you run the 6's and how long with 17psi?

Robert - will be curious to see how the IRI plugs go

Something else.... My Audi used to run 22psi of boost and made 50kW per cylinder and each cylinder was 450cc, my VR4 makes about 45kW per cylinder and each cylinder is 416cc so pretty similar. The audi got a new set of plugs every 100k but it did have coilpacks on all plugs. Sure there is more to it with 5 valve head vs a 4 valve head and other stuff but my gut feel is fix the ignition and the plugs will live.

My understanding is that most brand name plugs eg HKS, TRD etc are all made by Denso anyway but that could be a myth.... And just because Denso make them it doesn't mean they are made the same I guess but maybe someone who knows this industry better can shed light on that....

 

[pu-11-me]

Lemme see if I can find the plugs I pulled out of mine.... They were not anything that has been noted on this site so far, but I have seen them being used in Skylines?

I had them at 14PSI for 35k km's until they started missing. I only ASSUME they were replaced at 100k km service but I don't know, they look older than that to be honest. When I replaced them I also done the leads so I don't even know whether they were the problem.

I'll let you know anyways

 

[Guest]

i drive with 1,2 bar the same like 17,4 psi. the original plugs have been BKR6EIX, later i took 7` and after modificated exhaust, downpipe,piping and intercooler i have BKR8EIX.
but this was a long way to find out. for a long time i had front 6 and rear 7 (like non turbo mivec ftos).sometimes i had a kind like ignition cut and thought a leck in turbopiping and spend a long time to find error...
excuse me for bad english

Michael

 

[naughtika]

Dawso... if they were the ones from 123AYC and were from the 100k service.. from memory they were Greddy..

Michael.. haven't seen Iriway 8's locally.. well in qld..

*edit*

found a seller in ebay selling Iriway 8's

http://cgi.ebay.com.au/6-x-NGK-Irid...arts_Vehicles_CarParts_SM&hash=item4cf2a76f2b

 

[Guest]

Tim - how long have you run the 6's and how long with 17psi?

I would say they have been in the car 18 months plus now, generally I run the car at 15psi, but I have an MBC and with changes in season / temp this has led to boost creeping up higher. I would not say the car has been run with boost set this high (more than a couple of weeks) for long periods of time, however like I said when boost was up there no problems.

 

[twisted32]

I was thinking maybe -8's with 17psi.
Maybe you should try some copper -8's Steve, I my do this depending on how many km's I get out of the -7's

 

[ttgvr4]

I am now running plat plugs and 7 heat range sweet all the way to 17psi, SKR said use this combo and with the flash tune all smiles, i set the gap at 0.8mm

 

[twisted32]

I am now running plat plugs and 7 heat range sweet all the way to 17psi, SKR said use this combo and with the flash tune all smiles, i set the gap at 0.8mm

How long (km's) have you been running like this Steve, and which platinum plugs? It is not a question of it running well, but for how long.
Do you still have stock leads?
On another note, what mods and what power did you make with Steve?

 

[TME_Steve]

Yeah I thought of maybe 8's, most evo's are running 8's.... For the sake of the exercise unless someone else beats me to it, I'll give copper 8's a go after the 6's then.

 

[cittris]

Thought i would chime in here since i am having issues after putting new plugs in.

I recently changed my plugs to BKR7EIX from Denso plugs. I also put in new ignition leads from ICE.
Since then, the car has been misfiring when i run 15psi. Turn the boost down to 7psi and it runs fine 95% of the time.

Now my mate (Ash) is convinced it is the plugs and the the NGK plugs aren't all that great. I have cleaned my coil packs also.

The next step as far as i am concerned is the change the plugs again. Just haven't done it yet.

 

[naughtika]

I was using Iriway 7's gapped to .85mm it started jerking and sounding like a subaru after aboug 40k kms.. I really thought that it was the coils.. but after replacing the plugs, it went away..

 

[twisted32]

The thing with the Iriways or BKR7EIX's (they are the same plug) is that they are only iridium tipped on the centre electrode, but not the ground electrode like the laser platinum/iridium which are the stock plugs. This means that NGK only recommend that they last 60k not 100k like the OE's. After taking that into account, I think 40k from them in our application is not too bad.
After doing some research on plugs over the last few days, once we work out what heat range works best with 17psi (6,7or8) I will be trying either the laser iridium/platinum or denso VK series which are all OE spec, with both centre and ground electrode with iridium/platinum.