Spark Plugs

[njaremka]

this is probably the wrong place for this, but here goes:

i just wanted to share my experience with the group. i recently changed my spark plugs to bosch platinum +4's, and since then i have noticed a slight improvment in gas milage and smooth running. it has been talked about on this thread that since the design of the +4's is different, it can lead to early fouling and what not, and descreased performance. well, i haven't noticed any of those things. i also want to take this opportunity to say that since i had purcahsed the car, i have been running premium fuel (93 octane) with no bad side effects. i have also heard it said on this forum that 93 octane gas will cas more carbon build-up than 87, thus leading to poor performance. on my stock plugs i would average about 28-29 miles per gallon, and on the +4's i average about 30-31 miles per gallon.

well, here are my plugs. this first picture shows the stock plugs with about 18,000 miles on them, all but the first tank run on 93 octane gas. the second picture shows the +4's with about 6,000 miles on them, showing a similar color pattern to the stock plugs.

i plan on replacing my plug wires with either sparkco or magnacores in the future, and i hope these to give a similar bump in fuel economy/performance.

again, i share this as my experience. your mileage may vary.

 

[Gyre]

I put in high octane gas for the hell of it once. My gas mileage was slightly better but not enough to make up for the price difference in the gas.

 

[big_ben]

My gas mileage was slightly better but not enough to make up for the price difference in the gas.

Actually it will make up the difference in the long run. The extra milage offsets the price. So you can go with higher price and more mileage, or lower price and less mileage. You will be paying the same in fuel costs. But the in the long run, the premium gas will be better for the motor.

 

[Gyre]

Actually it will make up the difference in the long run. The extra milage offsets the price. So you can go with higher price and more mileage, or lower price and less mileage. You will be paying the same in fuel costs. But the in the long run, the premium gas will be better for the motor.

The price difference at almost 20 cents a gallon for 12+ gallons is over $2.40. That is more than a gallon of regular gas in NC (closer to two). The mileage difference I saw was less than that. Unless mileage would continue to improve on premium gas, I wouldn't save money in the long run. That's just my results. Some people may see a larger improvement ... or none ... or loss ... who knows. That was just one tank. A single sample is not good experimentation.

 

[scott42]

just to comment on the sparkco plug wires on mileage...I got almost 25miles more to the tank, and this tank, the second, I'm at 200miles at half tank...which equates to around 31 mpg...up from about 26 mpg (same driving habits). I plan on replacing my plugs very soon (I;m at almost 20k miles)

 

[saided18]

The deal about gas is simple. The only difference between 87 octane and 93 octane is that 93 octane can be compressed more before it ignites with out a spark. When the gas in a cylinder ignites with out a spark that cause your engine to knock. That is why octane is also referred as "anti knock index". So by putting a gas that can be compressed higher then the compression in you car will do no harm. That is why sports cars need 93 octane b/c the compression in the cylinders require it. hope that helps

 

[njaremka]

The deal about gas is simple. The only difference between 87 octane and 93 octane is that 93 octane can be compressed more before it ignites with out a spark. When the gas in a cylinder ignites with out a spark that cause your engine to knock. That is why octane is also referred as "anti knock index". So by putting a gas that can be compressed higher then the compression in you car will do no harm. That is why sports cars need 93 octane b/c the compression in the cylinders require it. hope that helps

finally, some one on this forum that has a clue as to what octane does for gasoline.

 

[saided18]

Thanx. i try.

 

[BigBlue]

The deal about gas is simple. The only difference between 87 octane and 93 octane is that 93 octane can be compressed more before it ignites with out a spark. When the gas in a cylinder ignites with out a spark that cause your engine to knock. That is why octane is also referred as "anti knock index". So by putting a gas that can be compressed higher then the compression in you car will do no harm. That is why sports cars need 93 octane b/c the compression in the cylinders require it. hope that helps

Learn something new every day....I didn't actually have a good understanding of this. Thanks for clarifying!

 

[saided18]

Glad to be of help. That is what this place is all about.

 

[scott42]

ok, question regarding when to change the plugs...due to the rich running that njaremka illustrated, when would be a good time to switch up/upgrade (well, anytime is a good time to upgrade) plugs?

 

[njaremka]

ok, question regarding when to change the plugs...due to the rich running that njaremka illustrated, when would be a good time to switch up/upgrade (well, anytime is a good time to upgrade) plugs?

the engine only runs rich when you get the rpm's up over 4000. that is why only the outside edge of the plugs is black like they are, and the electrodes are clean. (they get hot enough to burn the deposits off) another thing i want to point out, for those that think +4's only fire on one electrode, is the burn pattern around the center electrode. you can clearly see the four fire paths from the spark, confirming that it fires on all four electrodes.