Spark plugs: education required.

[RobStan]

Where can I learn about spark plugs?

I'd like to make an educated choice about what the 1600 needs without just asking the chap behind to counter for 4 plugs for a crossflow engine. And to be honest it's either reading about spark plugs or revising for an exam...

All opinion welcome. The engine is a 1630cc with 1300 pistons, fast road cam, standard 32/36DGV weber carb and bestek ignition kit. I don't use it for racing just pottering (with enthusiasm)

Cheers
Rob

[timelord]

I'm running NGK BPES7s in my 1600M, 1700cc Kent 234 cam and twin 40s, cured lots of misfire over standard plug. Geoff

[timelord]

Right letters wrong order BP7ES that's more like it !

[jpa]

Some questions answered here :-

http://www.sparkplugs.co.uk/pages/technical/spark-...

I have been using NGK BP6ES plugs and bought a set of 7s as have had the engine uprated a bit. However, I read somewhere that a cooler plug may be better these days as modern fuel burns hotter??!! Anyone got a definitive answer?

Paul.

[Monkeythree]

Not sure about "definite answer" but when I had my car rolling road tuned at Ric Woods in Stockport, one of the first things he did after the first power run was whip out the BP7ES plugs that I had fitted and replaced them with BP6ES. The engine build spec was similar to those mentioned above.
I had fitted the BP7ES plugs based on the research I'd done on Xflow build specs but Ric told me they weren't right for my engine.
Tom

[heightswitch]

If you are racing then you tend to use a "hotter plug". For road use the 6's which will be fine. This allows a better spark for the type of richer running a road driven car which isn't running flat out all the time gives and you will be much less likely to foul plugs.

N.

[Grantura2a]

I think that is backwards. Hot plugs for slow road, colder as you push harder. This is primarily true for older cars. In the old days we would start a car on the hot plugs, warm it up, then switch to the cold plugs for the race.

http://www.e3sparkplugs.com/news/hot-spark-plugs-v...

For many years, auto makers and mechanics recommended hot spark plugs for vehicles that primarily were driven slowly and for short distances, and cold spark plugs for automobiles driven on long distances and sustaining high speed highway use. Today, car and truck fuel/air mixtures and cylinder temperatures are electronically maintained within a much narrower range than before, primarily in an effort to minimize emissions. So, the practice has become a bit obsolete except when it comes to high performance race car engines, boat motors and truck engines. Because these engines generate crazy high heat, they often require colder spark plugs to keep the fuel/air mixture from igniting before the spark fires.

[mgmrw2003]

jpa said:

I read somewhere that a cooler plug may be better these days as modern fuel burns hotter??!! Anyone got a definitive answer?
Paul.

I had this debate when owned the 200SX as it was tuned. The entirety of the JapTune fraternity shall have you believe that cooler plugs are better, especially if running higher octane juice.

Eventually I swapped them, and added a larger fuel pump along with different boost set-up........... So in terms of Rolling Road results I couldn't find any standalone results.

BUT I did gain 90BHP through proper set-up, and the chap who did the RR specialised in rally cars, AND did classics. He basically said that theoretically it was wise, but he had no hard/fast rules regarding it.


In terms of driving on the road, I never found a difference IIRC