jeeper31

What is the difference between NGK BPR7ES and the NGK BPR6ES?

Called a shop and they said I need BPR6ES plugs. I think my car has BPR7ES. I know Amazon.com is not an expert but it says the BPR7ES won't fit.

jpk

It's just a difference in the heat range. If I'm not mistaken, the the higer number (BPR7ES) is one increment hotter. All this means is that the center electrode is extended just a bit further out than the cooler plug, so the center electrode stays at a slightly hotter temperature during normal running conditions. Going +/- one heat range from spec won't make that much difference.
I have a buddy that raced a little 125cc 2 stroke race bike years ago; he used to swap plugs and carb jets for the weather conditions. Typically, when he set it up to run a bit richer, he'd go one or two heat ranges hotter on the plug to keep it from fouling. Conversly, when running leaner, you reduce the heat range of the plug to reduce pre-ignition (knocking).

xsboost90

im running the 6es plugs- cooler heat range- supposedly its better for more boost.

67rschev

This is wrong . With NGK spark plugs , the lower the # the HOTTER the plug . It is also this way with ND spark plugs . The japanese plugs are opposite the american plugs as with Champion / Autolight ect , in which the higher the # the hotter the plug . You are right , with high boost / compresion u would want a colder plug ( the 7es )

jstand22

I need to change plugs too... so since my compression is 10:9:1 I should use a colder plug...but the car runs rich....so what plug should I use?

67rschev

Im not an engineer , but i will try to explain . The reason for running a colder plug is to keep the engine from detonating ( Ping or Knock ) . Detonation is caused by hot spots in the combustion chamber that under certain circumstances ( ie Hi Load , High Compresion , High Boost ) will start to pre-ignite the air/fuel mixture before the spark plug fires the charge . The spark plug then fires the charge and the flame fronts collide in the chamber and ' ping ' results . This unchecked will eventually damage the piston . SO if we run a colder plug , this in effect will have a slight cooling on the internals , as well as the plug itself will not become a pre-ignition point .

That being said , i would always run a cool a plug as possable . Why do you think your running rich ? Have you had it on a gas analizer or wide band o2 sensor ? 14.2 to 1 is optimal , but better hoarsepower figures are obtained at a slightly rich 12.5 to 1 fuel toair mixture ratio ..........

jpk

Thanks for clarifying - I thought all plug manufacturers used the same nomenclature.