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Plug Gapping

TriniGT

By TriniGT,
in Engines & Forced Induction

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TriniGT Experienced

TriniGT

Posted
Posted

I am in the process of eliminating things and I want to know what is the right gapping I should have on my plugs. I currently bought new Iridiums BKR7E-11s and gapped them down to 0.8mm but I am thinking that I may have damaged the tips when gapping one or two them. I want to know what is needed for my setup as I am going to be getting some coppers and replacing them today. I have a stock Neo RB25DET in an ER34, it has a FMIC, EBC set to 0.5 bar low and 0.9 high boost. I have used high boost once and won't be using that until I do upgrades later on. The car has a Trust Air Filter, Blitz ECU, and pther than that a Trust Oil Cooler; what gapping is recommended as I have a serious hesitation problem that I am trying to resolve?

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joeyjoejoejuniorshabadoo Grand Master

joeyjoejoejuniorshabadoo

Posted
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yeah i would stick with BCPR7ES and gap them to .8.

95% of r34 break down issues are related to the coil packs because they were very crappy from factory. known issue

+1 been using them gapped to .8 with splitfires for a couple of years now and no issues at all

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Tomei_Powered Rising Star

Tomei_Powered

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For Jap plugs eg. Denso, NGK, every 75hp - 100hp upgrade always move to a step colder plugs. Stock plugs, if im not mistaken is a .6mm or a .7mm.

The higher the no# the colder the plug is.

8 --- 0.8mm (.032'')

9 --- 0.9mm (.035'')

10 --- 1.0mm (.040'')

11 --- 1.1mm (.044'')

Go with a 0.8mm to be safe.

Best plug ive used so far is the NGK Iriway 8. Ive moved to 9 after mods.

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W0rp3D Grand Master

W0rp3D

Posted
Posted
For Jap plugs eg. Denso, NGK, every 75hp - 100hp upgrade always move to a step colder plugs. Stock plugs, if im not mistaken is a .6mm or a .7mm.

The higher the no# the colder the plug is.

8 --- 0.8mm (.032'')

9 --- 0.9mm (.035'')

10 --- 1.0mm (.040'')

11 --- 1.1mm (.044'')

Go with a 0.8mm to be safe.

Best plug ive used so far is the NGK Iriway 8. Ive moved to 9 after mods.

i believe stock plugs are 1.1.

Also i believe that the more mods you do the smaller the gap should be, hence why most people go from 1.1mm to 0.8mm.

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Beer Baron Grand Master

Beer Baron

Posted
Posted
For Jap plugs eg. Denso, NGK, every 75hp - 100hp upgrade always move to a step colder plugs. Stock plugs, if im not mistaken is a .6mm or a .7mm.

The higher the no# the colder the plug is.

8 --- 0.8mm (.032'')

9 --- 0.9mm (.035'')

10 --- 1.0mm (.040'')

11 --- 1.1mm (.044'')

Go with a 0.8mm to be safe.

Best plug ive used so far is the NGK Iriway 8. Ive moved to 9 after mods.

you are confusing gap with heat range. that advice above is wrong.

the number in the plugs for example 'iriway 8' is NOT the plug gap. that is the heat range. they are two different things.

the stock plug gap is not .6mm. they are a heat range 6 plug, with a gap of 1.1mm. yes as you get more power you need colder plugs. that has nothing to do with gap. you want the gap to be as large as possible without misfiring or plug arcing out. usually with more boost and power and colder plugs you need to close the gap down to about .8mm but if you can run more gap by all means do so as it gives a bigger spark.

there is also a suffix with NGK plug numbers. so a BCPR7ES-11 is a 7 heat range plug with a 1.1mm gap. a BCPR7ES with no suffix comes gapped to 0.8mm. a BCPR8ES-11 is an 8 heat range plug that comes gapped of course to 1.1mm and so on.

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R31Nismoid Grand Master

R31Nismoid

Posted
Posted

First things first... Iridi/Plati - waste of money.

Coppers, simple as that.

Second - plug gap depends on the setup. If the ignition system is WORKING WELL, a gap of 1.0 - 1.1 should be used for mild performance mods and boost.

Third - ALWAYS start @ 1.1 Gap and work your way down. Dont just assume 0.8 is 'best'. If your car runs well @ 0.9, use that - simple.

4th - search, there is a whole thread devoted to spark plugs, and its referenced from the FI Quick Ref Guide and fully detailed

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