Spark plug heat range - 6 or 7 ??

[Gizmo73]

Hey All..

Im looking at getting the iridium plugs (pre-gapped at .8mm), but it seems after searching that people use different heat ratings..

What is the recommended range for a car that would be pushing about 200RWKW in the future ??

I would think the BKR6EIX would be the go - however, if anyone thinks the BKR7EIX i would like to hear...

[The Dan]

yes, definately use the 7 as you will be pushing higher combustion temperatures so this plug is better designed for that....also I have more horsepower than this and the 7's are great....don't go 8 or 9 though, very bad.

[Gizmo73]

Great Daniel - Thanks for that ....

[GunMetalR33]

7 is good if you are running higher boost, but dont put them in until you have done your other mods. I think 7's might foul fairly easily on a stock line.

[Gizmo73]

...so if i went 6's now would they also do for when i up the boost to 12psi ??

[GunMetalR33]

I think 6's are too cold for 12 psi, 7 would do... I run 14 psi with sevens all day long and they work fine. I would only go 6's if you are having knock problems. Sometimes if your plugs are the wrong heat range or too hot like 8's or 9's they can act like glow plugs and cause you mixtures to detonate early in the cylinder causing knock.

my 2 cents, correct me if i am wrong

[BBQ]

I think 6's are too cold for 12 psi, 7 would do... I run 14 psi with sevens all day long and they work fine. I would only go 6's if you are having knock problems. Sometimes if your plugs are the wrong heat range or too hot like 8's or 9's they can act like glow plugs and cause you mixtures to detonate early in the cylinder causing knock.  

 

my 2 cents, correct me if i am wrong

Actually 6's are a hotter plug, 7 are a colder. you had it the wrong way round :-)

[gtst25]

I got sixes then mate/tuner said take them back and get sevens - it won't hurt.

I've had no probs running sevens with stock boost even on cold mornings and there's room for improvement next time we tune and up the boost.

[Gizmo73]

allrighty then - looks like im hearing a bit of support for the 7's..

Well ill actually do a correction - i am runing stock boost levels, but with the full exhaust and intercooler its actually running about 8psi at WOT (acording to boost gauge)..

But - thanks for the replies guys - 7's it is.

[GunMetalR33]

woops, you knew what I meant ....

Actually 6's are a hotter plug, 7 are a colder. you had it the wrong way round :-)

[BBQ]

allrighty then - looks like im hearing a bit of support for the 7's..

Well ill actually do a correction - i am runing stock boost levels, but with the full exhaust and intercooler its actually running about 8psi at WOT (acording to boost gauge)..

But - thanks for the replies guys - 7's it is.

I'm running 6's in my car at the moment, with around 15psi, but the plugs have been re-gapped to around .7 - .8, and haven't had any problems, the only reason I would go 7's is if I’m getting detonation or pre-ignition, where the plugs is re-taining the heat and as soon as fuel is pumped into the cylinder it ignites, at the wrong time... But with stock boost you won't have anything to worry about.

So most people go 7's if thier running more then stock boost, and usualy for a saftey thing.

[Gizmo73]

Yep - i just heard back from Repco..

BKR7EIX - not available, according to ngk - they only make them in BRK7EIX-11, which are gapped to 1.1m...and ngk dont recommend re-gapping iridiums...

BKR6EIX - available, $24 each.....

So - for the iridiums pre-gapped to .8m, i think i have to go 6's....

[BBQ]

I would go standard copper, They are much cheaper then Iridium’s.

The 6ES should be fine... Although NGK recommend PFR5G-11 for 93 - 98 for GTS-T I reckon they are too hot for our climate.

[Gizmo73]

Yea i know about the copper - main reason i wanted to go the iridiums is because i can change them way less frquently..

My intercooler piping crosses the block, so i have to disconnect it everytime i change the plugs...

So to go iridiums, it will save me time and $$ in labour...they last about 100k....

Looks like ill be going the BKR6EIX's...

[Busky2k]

I use NGK BKR7E (V-Power 'grooved' plugs) gapped at 0.9mm. Nope, no misfires, even at 17psi. These plugs are the best ive used (considering the platinums misfied like all hell at 0.9mm) and best of all, they're cheap! Stuff like octane booster fouls plugs easily, so if they are a bit shagged, toss em out and throw in a new set every 10,000ks...