Hi guys,

Im looking to buy some iridium spark plugs

However, I've noticed that some of the plugs are colder in the heat range.

it is said that "modified" engines should run colder spark plugs.

now, my question is… "what is…considered, modified"?

if i was to have;

• Boost actuator (20psi)
• full exhaust including dump
• Cold air intake
• ECU tune
• BOV
• larger throttle piping

is that classified as "modified" or basic mods to just run standard heat range sparkies?

Or "modified" means BIG power; Stroked, Large turbo, fuel pump, large injectors aftermarket ECU etc etc.?

 

Modified usually means a lot more airflow: bigger turbo, cams, etc. With basic bolt on you should be able to run the 7 heat range without a problem. The 8 heat range is quite cold and will probably foul at idle and part throttle for you.

You can get projected tips or non projected. Evo's come with projected tips from the factory. It is the spark plug code: BPR7ES would be a projected tip and BR7ES is non projected (those are copper plug codes, but iridium would be similar). Run a search to determine what you want.

Make sure you get NGK plugs. The benefits of iridium are debatable, but it that's what you want go for it. Make sure you gap the plugs correctly for your application tho. I would start with 0.028 and go down from there.

 

.020" gap or bust. .028 is a HUGE gap and will likely misfire on the top end

Also, for 9's the stock plugs are ILFR7H (different than the 8's, the 9 spark plugs have a longer threaded section)

 

The stock gap is 0.028-0.031. I recommended the smallest and to go down from there. Ideally you want the largest gap your car will run well with. Extremely small gaps tend to misfire at idle and part throttle. Large gaps blow out at high rpm's. It's a give and take. I find it's easier to start larger and go down. If your car works well at 0.020 great. His may not. He's got basic bolt on's so he's not terribly far off from stock. For reference I run a 0.025 gap

 

Stock is .020 - .024

 

I've run a .026 gap always. Never had a spark related issue in 150k+.

OP I agree with sticking with a 7 heat range plug for your mods

 

"Modified" in this context refers to a situation whereby the engine produces significantly more hp than the factory configuration. Because hp is synonymous with heat, this means the operating temperature of the factory plug my rise to a point that invites preignition. For a higher hp engine, a plug that is one step cooler will reduce plug operating temperature under load to within the original design spec.

This is true with gasoline only. An engine running E85 or other alcohol rich fuel generates cooler combustion temps under all operating conditions, and may experience fouling with a cooler plug.

 

yes i realised i didn't put the model. Which is the 2007 EVO IX.

But i am slightly confused…

so which is it;

BPR7ES ? or ILFR7H?

and i have seen both those part numbers floating around between 8's and 9's…

i might go smack-bang in between… 0.020 - 0.030 …. ill try 0.025 to start off.


Im glad I've did some homework prior to buying it… So thanks very much guys :thumb up: best forum i had ever joined.

 

Except the IX plug has a 26.5mm reach, while the VIII plug has a 19mm reach. This means you'll not be using an VIII plug in a IX head.

For a IX, you may want to switch to a Denso plug if you want to change heat ranges without scouring NGK plug technical data. Whereas the Denso IKH22 would be the factory heat range equivalent with an Iridium tip and nickel/copper ground, the IKH24 would be one step colder.

 

For an evo 9 motor (MIVEC), ILFR7H is the correct plug

For an evo 8 motor, BPR7ES is the correct plug

 

I've cut paste your post for reference. {thumb up}

At least because of the help i had received, i know exactly what i need to get, which is a; ILFR7H Heatrange 7 for mild simple mods.

rather than buying and realising something wasn't right

Thanks champion!

 

NGK gave me these part#'s for 4B11T

NGK#4786 LKAR8A-9 Or LKAR8AE-9

Anyone using them? They told me these copper plugs they recommend to people who want to run the NGK Racing plugs - but to avoid the cost and be able to run them in a street driven EvoX, they are much better in low boost or idle.

Any advice??

 

Wrong forum bud, this is the Evo I-IX section. Most here don't know which plugs are appropriate for the 4B11.

 

Well, I've been using the NGK R255 8 racing plugs which are meant for the 2009. Why I was asking as the plug dementions are all about the same. But for a street driven car they are rough at idle/low boost. Worried about fouling them.

I'll check the other section though. Thanks anyway.

 

Would aftermarket spark plug leads make much of a difference, since I'm adding iridiums?

or is it just marketing…?