spark plug heat range advice

[chris-mr2]

Interested to know what heat grade plug is recommended for a meth injection setup, im currently running a 8 grade instead of a standard 6 grade and my plugs elctrodes are very clean and slightly white whilst the rest has a sooty coating.

Im aware allot can affect spark plugs but am keen to find out if others run standard heat grade plugs or colder ones like me

[chris-mr2]

Here's a pic off my plug

Engine is a highly modified 2 litre turbo running 60/40 water meth mix at approx 15% to fuel, 23 psi boost, stand alone ecu mapped for meth etc....

[parmas]

I have a toyota yaris engine converted to turbo with 8.5 compression instead of 10.5. Running 18psi on a gt2560r turbo. Stock aspirated plugs are heat ranged 5. I used stock plugs for a year and worked fine. Now I am on heatrange 6 for safety.

Yours seems iridium and seem rich. I use standard plugs

[chris-mr2]

Id not thought about the tip material, is iridium not suitable for contact with methanol?

[Flr Power]

It would not be exposed for a long time compared to total running time without water/meth injection.

[parmas]

Originally Posted by chris-mr2

Id not thought about the tip material, is iridium not suitable for contact with methanol?

Mainly due to cost. I do not saw difference between stock vs iridium. Some claim that iridiums tend to blow the spark by boost

[chris-mr2]

So to sum up, the fact that water meth is in cylinders cooling the charge doesnt affect the heat grade of a spark plug by cooling the plug directly?

[parmas]

Originally Posted by chris-mr2

So to sum up, the fact that water meth is in cylinders cooling the charge doesnt affect the heat grade of a spark plug by cooling the plug directly?

Chris, if the cylinder / combustion is cooler / the plug is cooler aswell !

So when cooling the charge by means of extra fuel or water the plugs result cooler. Too much cool charge and you foul the plug !

[chris-mr2]

Thats what im trying to get my head round, correct me if im wrong.....

i have gone from a grade 6 plug to grade 8 (2 steps colder i belive) to dissipate heat from the plug more due to increased power and boost etc

What im trying to find out is that seeing as my plug is colder due to the water/meth do i need to be 2 grades colder, or would a grade 7 be more suitable

[parmas]

Originally Posted by chris-mr2

Thats what im trying to get my head round, correct me if im wrong.....

i have gone from a grade 6 plug to grade 8 (2 steps colder i belive) to dissipate heat from the plug more due to increased power and boost etc

What im trying to find out is that seeing as my plug is colder due to the water/meth do i need to be 2 grades colder, or would a grade 7 be more suitable

Specify your engine vs stock engine (if upgraded) in terms of boost / rev-limiter / engine compression / upgraded cams ?

Also what air temperature readings are you getting while water injection and what are your ambient temps ?