I guess some of you will be interested in this. All tests were done by bmwservice.livejournal.com
Full test and some sort of FAQ you can find here
. Use google translate
#1 from FAQ needed for reading results:
"Spark plug sparking stability depends on various parameters, like constructional - related to spark plug itself, and enviromental - temperature, pressure, humidity. Constructional parameters, as seen from test results, have strong affect on result - not only on "quality" of spark, but even on the fact of it's presence in difficult conditions. Spark plug gets the most abuse when you go from low % throttle to full throttle in short time - pressure in combustion chamber changes abruptly and is about 20-30atm. Especially this can be applied for "pressurised" modern turbo engines... However even on NA engines you can see combustion beginning absolute pressure about 18-20atm, which you can check yourself by doing motortest with pressure gauge."
Spark plugs are tested for misfire under pressure.
1atm | 8atm | 16atm | 20atm | 25atm
14.6psi | 117psi | 235psi | 294psi | 367psi
Worlds standard: 8atm+
Best you can find: 25atm+
Spark color reference picture, the colder the better. (the more close to blue, the better the spark is)
DENSO VK20 5604
Pretty expensive "premium" spark plug (about 700 rubles - $21 each), undoubtly nice construction design. Expected excellent result. [These comments are translation from original post, prices are local. - lokiinlove]
One of the most expensive spark plugs in this test - more than 1500 rubles [$45] each. What's remarkable here, is a "flush" electrode. These spark plugs are designed for high RPM - the spark sholdn't be "blown away". Result - perfect.
DENSO W20TT HK
Regular, budget series, really cheap (only 100 rubles [$3]) spark plug, but the idea of the "return part" [nipple on the ground electrode] is original, and what's more important, it works... Excellent.
BERU SILVERSTONE S5
Настоящий спортивный ветеран от BERU, в виду возраста - недорогой (200 рублей). Отличный результат, если, конечно, вы найдете их в продаже...
The sport veteran from BERU, considering age - not expensive (200 rubles [$6]). Excellent result, if you can find these in stock...
BOSCH PLATINUM FR7DPX R3 781
Very cheap (less than 100 rubles [$3]) and original appearance. And advantages end here. Holds "world standard" and a little more, but fails after - definatelly design fail.
BERU PLATIN 14FR-7DQUP7 R6
Multi-electrode spark plug of "average category" with average results... Again, construction design fail.
One of the most cheap participants: 70 rubles [$2], design - cannot be more simple. However it works and pretty good, no misfires.
DENSO IRIDIUM POWER IK16 5303
Averege priced iridium spark plug. 400 rubles [$12] of stable result throughout the whole pressure band.
[local brand, never heard before]
Domestic multielectrode breakthrough engineering [sarcasm]. On of the cheapest products of this manufacturer - 200 rubles [$6]. Works excellent by the way.
Dudyshevs cannon-spark plugs
[again something local, never heard before]
Advertised 13atm, but work good till 25atm. But the price will surprise you... [googled $13 per item]
[lol i googled this stuff, they advertise "10% less fuel, 10% more power, 60-70% less emissions" + some pics:
right.... Back to topic))]
Thin electrode + needle on ground. Something like Denso TT series, but iridium. Stable as expected.
VAG BOSCH BOM 06H905611 R1 DC
OEM spark plug, perfect, expensive.
BOSCH SUPER PLUS FR8DPP33+
Cool and reasonably priced (about 200 rubles [$6]).
NGK VAG 03F905600A R1 NG4
Somewhere above you can find almost the same one from another manufacturer. Result is the same. Excellent.
Spark plug with a little wierd appearance: modified electrode. Budget of course. Haven't expected anything special, but works with no issues.
NGK IRIDIUM BPR6EIX-11
Again, classic iridium design with classic result and average price... Excellent.
BOSCH SUPER4 WR78X R6 208
Relatively cheap multi-electrode option for old engines. Very competitive result compared to multi-electrode spark plugs...
GM ACDELCO BOSCH 9222-447 HR8NPP302
OEM GM. Average result. Considering this is modern spark plug, result could be better.
BOSCH SUPER PLUS WR7LTC+ 208
Cheap, multi-electrode, very good.
NGK R ZFR5V-G
Classic spark plug, with stable excellent result. Not rare for regular budget spark plugs btw.
Pretty famfamous in VAG AG clubs spark plug. Without doubt only two lower electrodes are operating, however, regadless of worthless design and pretty weak spark (judging by color and color temp), spark plug is operational throughout the whole pressure band.
BOSCH SUPER PLUS FGR7DQP+
Averege prices, original, but haven't moved far in physics understanding. As expected, result is average.
NGK R BKUR6ET 10
Cheap, works flawlessly.
NGK R BKR6EQUP 3199
Widespread through old BMW motors owners. With current price is highly acceptable.
BOSCH SUPER PLUS FGR7DQE+
Budget anlogue of the above one, but because of uncarefully crafted center electrode the spark is less powerful and cannot resist high pressures.
BOSCH PLATIN F5DPOR R1
"Sport" one from BOSCH. Pretty expensive, looks like handcrafted
however this is one of the best spark plugs in this test. Physics of this design is close to perfect "needle to needle". Shielding/srceening by ground electrode is minimal.
DENSO K16R-U11 3120
Don't ask for more for this price.
DENSO VK16 5603
Expectedly good, almost excellent (25atm+ misfires could be an issue of this particular sample).
DENSO PT16VR13 5068
According to specifications, suits only one (!) motor. Average result, probably really suits one motor.
Dudyshevs spark-plug based on А17ДВРМ (A17DVRM)
Modified and fully operational. Fixed by Dudyshev.
NGK R BKR5EKUP 2890
Not bad and pretty cheap.
NGK R PFR6Q 6458
If you have something personal against iridium, this is your platinum choice.
BOSCH SUPER F7LDCR
Stock spark plug for majority of old BMW engines. As seen from test - a good quality item.
PULSTAR be1i iridium
Innovative "condesator" spark plug - pay attention to the spark "size".
Additional: misfire vs spark plug gap relation for selected participants
How cold temp affects spark plugs operation (cold start imitation):
High temperature test: