[Southcross]

Has anyone experimented with non-OE (i.e. non-Iridium) plugs in our ICEs?

It has been a long standing argument among the VW community (cars in the 2000s and newer generations) that you get (significantly?) better fuel economy with Copper plugs over Iridium at the cost of the plugs wearing out 2-3x faster.

At present I drive a lot of ICE miles, so I'd be willing to Guinea pig myself if I can determine what plugs are "compatible"

 

[Southcross]

Specs according to NGK (my preferred brand)
https://www.ngk.com/product.aspx?zpid=30795


Shell

Thread Size: 14mm
Thread Pitch: 1.25mm
Seat Type: Gasket
Resistor: Yes
Resistor Value: 5K Ohm
Reach: 19mm (3/4")
Hex Size: 5/8" (16mm)
Terminal Type: Solid
Overall Height: ISO
Gap: .028" (0.7mm)
Heat Range: 6

Which equates to a BPR6ES spark plug gapped to .7mm... (which makes me laugh, as that is the EXACT same plug I use in my old VWs)
**EDIT
correction.. NGK says it is a BKR6ES plug, i'll have to pull a plug to verify the actual Hex size
https://www.ngk.com/Automotive-NGK-c1411.aspx

 

[srmarti]

I'm skeptical. Once you have sufficient spark for consistent ignition what exactly is more going to do? How much better fuel economy improvement is "significant"? Are they simply comparing worn out Iridium plugs to new copper ones? Maybe the Iridium are still performing well while the copper ones are already shot and need replacement? How does that figure into the economics?

 

[alfon]

I find it somewhat hard to believe that current iridium spark plugs, which are good for well over 100,000 miles, are less efficient than standard plugs in the same engine. I would like to see a test for mpg with iridium plugs and regular plugs for comparison.

 

[mpmoore1979]

Simply put, if this was true then all car makers would be using them. I am sure GM would love to get better MPG just by replacing the spark plugs with a cheaper part and get better MPG. Be warned about all claims of better hp, mpg and lower emissions by replacing a simple part!

 

[Dutch]

I had a 72 Dodge Dart Demon. 340ci V-8 that was tuned up pretty well and had the kind of strong engine that pulled 0-60 in about 6.7sec and regularly pulled mid 15's on the 1/4 mile drag strip.

I used to run some slightly "hotter" plugs in it trying for more "juice" and about the only thing it seemed to do was make the car start a little easier. I tracked absolutely NO difference in horsepower (had access to a dyno) or MPG or 1/4 mile speed or anything.

1997 Jeep Cherokee, decided to try some "fancy" NGK plugs one time and it was astoundingly awful. Lowered MPG, one cylinder fouled (which had NEVER happened before). Truly a disaster. I went back to the stock Champion plugs and have been happy for the last 160+k miles.

My own personal experience has been that the factory recommended plugs are generally about the best thing you can put in a regular commuter car.

 

[voganni]

I agree with Dutch. OEM's do a lot of research analyzing all engine operating parameters and choose a plug that is the best fit overall. Staying with OEM has worked best for me over the years. Different plug manufacturers' heat range characteristics are not EXACTLY the same across brands. I would stay with the iridium plugs however.

 

[freshcut]

I always tend to stick with OEM or equivalent myself. I had one co-worker who "upgraded" her plugs to some new pulstar plugs. Initially she was pleased with how much smoother her car ran and the mileage improvement as her old plugs were worn and required changing anyway. Within a month she had numerous issues where the engine would just die or run VERY rough accompanied with multiple check engine codes. Oddly enough none related to misfire or specific cylinders. After a visit to the dealership for work it was determined the pulstar plugs were at fault. Swapped out with new OEM style and all has been good. Only took $600 at the dealership to find that out.

 

[Southcross]

this is actually a widely debated topic in the VW community... the only plus side that can be agreed upon with Iridium plugs is the 60-100k mile service interval (vs 20k on Coppers). And when I say "significant", I'm talking 10%, so... 4-5mpg highway (observed on both the 1.8T and Vr6 2.8L engines)? May not be significant to EV mode drivers, but I drive about (at present) 75-80% ICE, that would equate to 40ish miles to a tank... or 1 gallon @ $3/gallon... the cost of two plugs. Based on my typical annual driving a savings of about $65/year, or almost $200 in gas between plug changes.

naysay or not, I plan to give this a try, just curious if anyone on here has experimented

 

[Jefferios]

20K replacement cycle is 1-2 years for more drivers. There is no way I'd want to change spark plugs that often. Good luck on your tests and please report back.

 

[Dutch]

20K replacement cycle is 1-2 years for more drivers. There is no way I'd want to change spark plugs that often. Good luck on your tests and please report back.

LOL... yup, it was plugs, distrib cap, and rotor every damned year on the Jeep for a while.

 

[canehdian]

20K replacement cycle is 1-2 years for more drivers. There is no way I'd want to change spark plugs that often. Good luck on your tests and please report back.

Though for a volt that could be far longer. Perhaps 100 driven, 20 on the engine.
Could be an interesting way to boost MPG with little effect (if it's even a measurable difference)
For sure the volt usage pattern would make it easier to measure such a difference as opposed to an ICE-only which has many, many more variables per tank of gas.

 

[Norton]

.... you get (significantly?) better fuel economy with Copper plugs over Iridium .......

Oh yes,, A spark in a gap is not just a spark in a gap. It matters what metals the spark is between.

When I was younger I bought a J.C. Whitney GAS SNAKE !
You drop it in the gas tank and it consumed impurities in the gas and resulted in 110% (significantly?) better fuel economy.
It was not fun having my tank over flow...

 

[srmarti]

this is actually a widely debated topic in the VW community... the only plus side that can be agreed upon with Iridium plugs is the 60-100k mile service interval (vs 20k on Coppers). And when I say "significant", I'm talking 10%, so... 4-5mpg highway (observed on both the 1.8T and Vr6 2.8L engines)? May not be significant to EV mode drivers, but I drive about (at present) 75-80% ICE, that would equate to 40ish miles to a tank... or 1 gallon @ $3/gallon... the cost of two plugs. Based on my typical annual driving a savings of about $65/year, or almost $200 in gas between plug changes.

naysay or not, I plan to give this a try, just curious if anyone on here has experimented

I'd like to see test results of new iridium plugs vs. new copper plugs. Ideally it should be double blind so the driver doesn't bias the results. 20k copper plugs vs. 20K iridium plugs might be interesting too. 10% over worn out plugs, yea I guess so, maybe. 10% better than new plugs, I doubt it.

Look forward to seeing your results.