Spark plug question

[T40ORA]

What is the benefit or dis-benefit of running a hotter plug? Manuals stat I should go for a BKR6E but I have been advised by a knowledgabe person to opt for BKR5E which apparently slightly hotter. TBH I don't really know what that term means; do they perform better when the temperatures are higher or do they generate a hotter spark?

TIA!

[RobCrezz]

T40ORA said:

What is the benefit or dis-benefit of running a hotter plug? Manuals stat I should go for a BKR6E but I have been advised by a knowledgabe person to opt for BKR5E which apparently slightly hotter. TBH I don't really know what that term means; do they perform better when the temperatures are higher or do they generate a hotter spark?

TIA!

What car is it? Is it tuned?

If not, best use the recommend heat range.

Its not referring to the heat of the spark, its referring to the heat at which the spark plug operates best.

If you tune an engine you generally go for a colder plug as the combustion temperatures will increase with the higher torque generated. If you go too cold then you can get deposits form on the plug because its out of its heat range and eventually you will loose your spark. If you go for a too hot plug then that can cause pre ignition.

[B'stard Child]

T40ORA said:

I have been advised by a knowledgabe person to opt for BKR5E which apparently slightly hotter. TBH I don't really know what that term means; do they perform better when the temperatures are higher or do they generate a hotter spark?

TIA!

Hotter or colder has nothing to do with the spark and everything to do with ability to remove heat (or not from the plug) - think of it in radiator terms - big surface area conducts more heat to the air around it - small surface area doesn't transfer as much heat to air around it (same temp water for both)

Another Ph'r has explained the issues around running a cooler or hotter plug than OE specified

[B'stard Child]

NGK web site is full of usefull info



NGK PLUGS GET COLDER THE HIGHER THE NUMBER, HOTTER THE LOWER THE NUMBER.

Say you are starting with a BKR6E-11
if you want a colder plug, you would use BKR7E-11
if you want a hotter plug, you would use BKR5E-11
(again, on non-racing plugs, the number after the "-" refers to the gap)

Edited by B'stard Child on Thursday 26th April 16:44

[Ozzie Osmond]

PH myth number 4,002

"Manufacturers don't fit the right plugs"

See also thermostat, brake pads, air intake, oil, ECU ....

[T40ORA]

Apparently 5Es have a better operating range, so I will give them a try. May compare them back to back against a set of 6Es.

[FoundOnRoadside]

Ozzie Osmond said:

PH myth number 4,002

"Manufacturers don't fit the right plugs"

Well, actually, Ford fitted the wrong plugs to the MZR engine in the Mondeo for years. Only decided to change the standard gap setting in 2006 or something like that. Changed from 1mm to 1.3mm (or the other way round, can't remember).

And as for the factory map...well OBVIOUSLY that huge hole at 2500rpm was intentional, right?