spark plugs and fuel econ

[topcat]

www ngksparkplugs.com/techinfo/spark_plugs/installation.asp#indexing

Quote:
Indexing

This is for racers only !!
Indexing refers to a process whereby auxiliary washers of varying thickness are placed under the spark plug's shoulder so that when the spark plug is tightened, the gap will point in the desired direction.

However, without running an engine on a dyno, it is impossible to gauge which type of indexing works best in your engine. While most engines like the spark plug's gap open to the intake valve, there are still other combinations that make more power with the gap pointed toward the exhaust valve.

In any case, engines with indexed spark plugs will typically make only a few more horsepower, typically less than 1% of total engine output. For a 500hp engine, you'd be lucky to get 5hp. While there are exceptions, the bottom line is that without a dyno, gauging success will be difficult.

[Execut1ve]

precisely

[Ford Man]

Originally Posted by Ryland

So your car asks that the plugs be changed every 15,000 miles or so? copper core plugs degrade over time as the tip wears, platinum tipped plugs wear much much slower but platinum is a poor conductor in comparison so they will perform about like a copper plug would at 10,000 miles only they will be there from the point of new all the way up to 100,000 miles while costing 5 to 10 times as much.

Platinum plugs usually are not even twice the cost of copper core plugs, but last several times longer.

[Execut1ve]

doesn't mean anything to me since I follow the maintenance schedule in the owner's manual and change the plugs every 30k mi. The plugs are changed, along with the rest of the 240k mi maintenance, with the exception of the tire rotation... I managed to break a wheel stud never have that happen to me before. so now I'm trying to figure out how that is to be fixed.

[cistercian]

I am going to try the Denso plugs in my 95 civic....in a few weeks.
I will let you know how they compare to the NGK I am running now.

[Execut1ve]

excellent, I will be very interested to see if there is any noticeable improvement in fuel economy