jokerswld34

looking to buy some new plugs and was wondering where i can find these ngk ix iridium for the 4 cyl kompressor application? i am looking to go a step colder which i believe would be a heat range if 7 over the factory 6? if there is another plug that would be better performing in an engine with modifications, please make a suggestion. ive stf and have come up empty and cannot seem to find a shop to buy these plugs, although i know some of you are using them. thanks so much!

skittles

i got mine off ebay. watch out on these plugs man. your MPG will change, big time. in exchange response is so much better. im gonna switch back to OEM bosch pretty soon. gas in goin back up. lol.

FrankW

I'm currently running them on my M112k (bought them when troubleshooting idle issue) . noticed a drop in mpg after everything is fixed, but better throttle response since these has .039 gap vs .040 gap. might put my denso ik20 back.

combined went from 16.7mpg to 15mpg. lost about 20mile on avg per 14 gallon.

nuclearhappines

Response is better, power was smoother ... and my occasional problem of the car falling flat on its face with timing being pulled out in the middle of Saudi summer heat was eliminated.

Can't comment on the mileage, my car has other stuff done to it , and 1 vacuum leak i need to fix so yeah my mileage is lower than stock... but my power is always available.

You can order them here

edit, i'm using the Greddy L7's which are just repackaged / relabeled NGK 7s... you know the greddy sticker adds 10hp .

seriously , the guy i order my parts from had the greddy's in stock and no NGK, so i went with that, but it's the same thing ...

HKS relabels Denso plugs
Greddy relabels NGK

jturkel

Frank. that gap is absurd. the stock gap is like .036 or .035. mine are gapped to .034 per the recommendations from Brandon (code3) and LET. might want to consider gapping them closer together?

FrankW

I'm confused here.

from OEM parts search 2002, 2003, and 2004. all of them shows either .039 or .040 as stock gap and the original NGK OE Laser iridium I first pulled out part # matches with the .040 gap.

my denso IK20 is .040 gap and the iridium IX i'm running now has .039 gap.

I thought they/LET/code3 just re-gaped it to get more intense spark out of it. not because OEM's gaped that way?

jturkel

hmm....maybe i was misinformed on the stock gap......

but, i know that MOST people over in the 32 section who have new plugs are around .033-.035 with most at .034. i was told that was the optimal gap especially if you running more boost and have colder plugs

splinter

What prompted you to seek fitting colder plugs?
Have your OE pieces shown the telltale signs of overheating or pre-ignition? Perhaps your "PowerChip St 2" tune has increased combustion chamber temperatures such that they’re unable to properly cope with extended WOT sans failure.

Trust you’re aware that your M271’s OEM Bosch F6 MP 322 plugs have a reach of 26.5mm. Note that the typically recommended ‘performance upgrade’ plugs for this engine will screw into the head nicely, but they’re far too short sit properly within the chamber to initiate seamless flame propagation. A few here have been caught out by unwittingly installing cross referenced hardware that the various spark plug manufacturers’ catalogs recommend as the correct plugs. Their BKR6EIX or ZFR6FIX-11 will not work correctly in the M271. Neither will Denso’s IK2x line. NGK’s ILFR7A is their next step colder for your engine. Motorcycle tuning shops typically stock them in their consumables inventory.

Not trying to bust your *****.
Don’t want to hear of anyone throwing good money after bad only to read of it possibly losing a portion of the performance for which he has already paid.


Some guys get too worked up over a few thousandths. =)
MB’s spark plug gap specification for their M111 and M112 is 1.0 millimeter/.039 inch.
It’s 0.8mm/.031 inch for the W203’s M271 and M113.

Those running more than ~18 psi of boost could experience reduced misfires at the top of the rev range by slightly closing their plugs’ gaps. Increased combustion chamber pressures have a tendency to ‘blow out’ the spark with an otherwise marginal ignition system. I’ve not experienced it. Downside is often less crisp part-throttle driveability. More often than not, it’s a faulty tune or fuel supply system going lean that manifests itself as ungainly or misfiring WOT operation.

FrankW

I think mine would be okay since I'm only on 178mm. same as John's setup.

I'm just curious if .039 gap made a fuel consumption difference from when I use the Denso IK20 at .040 gap. small difference. all I know is after getting the car back I've ran through two tank of gas and only getting 15mpg avg vs 16.7mpg previously. maybe it's just because I'm heavier on the throttle a lot since I got the car back to health?

FrankW

john,

I understand that smaller gap creates the spark more intense and quicker, correct?

was just reading around and some people online mentioned smaller gap could also cause lower mpg vs proper gap?

splinter

Reducing the spark plugs’ gap makes it less taxing on the ignition system’s coils to generate sufficient juice to bridge the distance between the center and ground electrodes. It’s an inherently “weaker” spark because there is less electrical amperage required to span the decreased distance. It’ll also cause the spark –not necessarily combustion- to occur a few milliseconds sooner owing to the decreased dwell time required to generate sufficient strength in order to generate the arc.

Larger gaps (within reason) typically result in smoother light-load operation and improved fuel consumption figures – if the system can fire them and they’re able to properly initiate combustion. Not normally an issue with the M112’s twin-plug design. Somehow registered 0.0% Carbon Monoxide and 1 PPM Hydrocarbon readings during its most recent tailpipe emissions inspection. Friendly smog check technician mentioned nothing of its underhood goodies.

An accurate fuel consumption average can only be calculated over several thousand miles. Quite pleased your ’32 is again running at full vigor. Another canyon cruise happening soon? Until then, keep your foot off the loud pedal. :D

jturkel’s post on reducing gaps as a legitimate crutch to reduce WOT (plug/ignition system-induced) misfires on highly boosted applications is well founded.
I’ll spare this particular thread the details of verifying a spark plug’s proper heat range for another occasion.


photo credit vrus

jturkel

i know there is a thread dedicated to you, but seriously, you're amazing. thanks as always for your input. i enjoy reading all of your insightful posts!

FrankW

thx john, for the great explanation.