Go with NGK 8's.

The NGK use higher numbers for a "colder" plug. If ylu have had no fouling issues on the HKS which is equivelent heat rating there is no need to change.

Only reason to go hotter is if you were having issues fouling plugs, ideally its recommended to go one grade colder per 100hp gain over stock (what I've read anyway).

Too hot a plug can cause pre-ignition, detonation and engine damage.

I've run BKR8EIX in my GTO-TT for years, excellent plug and give a nice smooth idle.

 

Along with a set of decent plugs one of the best mods you can do is to improve the ignition harness with a direct feed back to the battery.

http://www.gtr.co.uk/forum/177426-do-luck-ignition-harness-rb26dett-new.html

 

Soo not required.

It's really easy to diagnose transistor pack wiring issues.
There is no advantage will bigger cable, it's the connector on the end that's the bottle neck and this 'Kit' does nothing to change that.

 

Thanks for the advice, it's definitely worth looking at at some point.

I'm going to get BKR8EIX purely because that's what was installed previously with good results / no problems.

What I was curious about was why they weren't 7s, which most people seems to recommend at this power level.
Just trying to understand this subject a bit more.

 

Can you post a picture of one of your plugs fresh out of the engine?.

The heat range is basically how much heat is transfered from the plug to the head. You want to run as cold as you can without fouling issues really on a turbo car.

It's all to do with the construction of the nose of the plug.

 

 

If you see the 5 grade plug has more unbonded ceramic insulator (will heat up quicker/ clean at lowed engine operating temps). The 7 grade plug has more bonded ceramic which pulls heat away from the tip of the plug and into the cylinder head to be removed by the coolant flow.

Less chance of pre-igniting the mixture with the cold plug which is the last thing to want under boost. Get too hot a plug and it acts as a "glow plug" so you don't have control over the ignition of the mixture.

 

BKR8EIX are the way forward. You should be able to get away with the 8s. The only reason you would run the 7s is you get a bit of misfire when cold. The 7s will be better at cold temps but it's a compromise you have to make for a better burn at normal operating temps.

 

Heat Range Conversion Chart:

HKS
25 |30 |35 |40 |45 |50 |52.5 |55

DENSO
16 |20 |22 |24 |27 |31 |32 |34

NGK
5 |6 |7 |8 |9 |10 |10.5 |11

And yes, get yourself a Do-Luck harness, we have plenty in stock and it really does make a difference. Also, do you already have Splitfire Coilpacks?

 

I will second that my coil loom was pretty beat up also part of the loom are crimped up and the metal tabs had corroded. People spend more money on unnecessary bling when this would give them some improvement and reliability.

 

This is a bunch of spanners:

We are people, with opinions and thoughts and good or bad product expreriences.
Above all, we're traders that contribute to the community with good discounts, product advice and food for thought.

- You do not need to fit another relay
- If you use the direct power feed, yes you will need to run a line to the battery
- Extra ground connections is never a bad thing
- I did give him the heat range table, and advised him to change to a new harness to rule out bad wiring

Yes, it will not help OP understand the heat range issue, but it will cancel out the possible problem of faulty / broken / damaged / worn out wiring.

Did you buy one? Test one? Use one? If not, then you cannot say it's less or more reliable than the Nissan loom.

Endless discussion, just as the Skylab ETS versus the Do-Luck ETS.
Why don't you buy one, i'll even give you a fair discount, and test it? I don't want angry people that didn't try it. I'd rather have people that have tried it but didn't like it and tell their reasons and show the results?

Examples of OEM wiring:

 

The thing is, I don't sell on miss information.
You assume I have not tested DO LUCKS ETS?
Assume nothing.

Believe a DO LUCK harness is better than a Nissan harness, believe stereo plugs are better than Sumitomo sealed plugs, believe a perminant live to the coils is safe, believe you NEED one, believe all than and buy one.

 

We are selling on miss information? Can't really believe you just said that about a trader that exists for over 25 years and joins the very best on the list of top names in the motorsport branche.

Shame on you, this discussion is done for meuke:

 

Chillout everyone,

Why do people have to argue,

I see points from both sides.

Now I run NGK 8's, stock coil harness stock coil pack (no problems with it at all) no misfires.

Now if it was me id replace the plug, if found other issues id then look to change them up. But finding the problem rather then throwing money at it is a better approach.

Do-Luck harness is not bad, its just a small upgrade, but the stock is fine if you ask me. Some times its an AMP problem, then it could be coil packs, timing, AFM, o2 maybe the list goes on.

Try checking all your coil packs to see if any of the springs have fallen out. Then test your coil packs and loom. Eliminate first then buy second. If you don't no call an expert ))))

Mikey

Traders are always looking for the sale on here so really your advice should be to test the harness first to see if that is at fault. But then you would lose the sale right lol

 

I have always used a 7 range plug in a 500bhp tune running 1.3 bar. Some people seem to get away with an 8 with no issues.

As for the harness debate I had misfire issues at 6000 rpm having changed the amp and plugs I decided to try the Do Luck harness which cured it.

Andy I do not understand why you feel you need to slate the product?

 

Great thanks to keithmac and Jimbostir, exactly the info I needed

I finally have some time to change the plugs (2 months after buying them lol), will try to take some pics to post them later