Spark Plugs: NGK or Denso?

[MichaelCT]

My BMW specifies a few revisions of NGK, and I go with the cheapest one (which weirdly is the doubled platinum, single is the most expensive and iridium is in between but uses different ignition coil).

The point is, for oem plugs, just go with whatever is cheaper, they should perform the same. (In my example, the iridium would be too fouled before reaching the electrode's life, they would still be changed at the same interval)

I always liked NGK for both VWs and BMWs, they were the OEM supplier. I would gladly try Denso but they cost more than NGK for my cars so I am definitely not paying extra for them.

 

[ARCOgraphite]

My 91 Honda CRX Si came from the factory (Suzuka, Japan) with Champion spark plugs installed (RC9YCN4). I was shocked when I did the first service on it and pulled a Champion out of the cylinder head. Ran perfectly fine, but I've run NGKs in it ever since.

Ou old Subaru 1.8 had champion RC8YC4. Ran like junk on the hotter plug (9) and like junk on NGK.

NGK had then GND electrode and used to cause preignition and they would erode quickly. Junk.

It wasn't till the modern coil on plug and NGK Ir plugs that I would run a NGK.

Some engines are picky about heatrange especially during pre OBDii and leaner running factory tuning

 

[keyboardguy]

For what it's worth;

I flew ultralights in the early 80's. My plane had a Yamaha 2-stroke go-cart racing engine, one cylinder. The NGK's were about a dollar.
Prior to takeoff, I installed a new plug (new plug every few hours of flying).
It failed.

Went to Champions and never put in a Japanese plug again.
Paranoid ? Yes, but it was my *ss on the line......
My Hyundai has Japanese plugs I'm sure, but then again I'm not cruising at 5,000 feet.

 

[daves87rs]

NGK