D16 Spark Plug Guide

The Honda D Series engines (D15, D16 and D17) are well proven engines found in a wide range of Hondas throughout the 90s and early 2000s such as the Civic, City and other small eco Hondas.

The D series Vtec engines packs a big punch for such a small package and respond GREAT to a few basic mods. Those looking for big power gains can easily bolt on a turbo kit and make anywhere from 200-350hp on the stock engine. With a set of forged pistons/rods and sleeves the D series engines can support 500hp+.

D Series NGK Iridium Spark Plugs

Our partners at FFrides keep a HUGE inventory of all the popular ngk spark plugs ready to ship at your convenience FFrides is our go to source for ALL NGK spark plugs.

If you don’t remember the last time you changed your plugs or you simply want to ensure your car is running perfectly, swap in a fresh set of NGK plugs and enjoy!

If you have any questions comment below, email or call any time.

ngk iridium spark plugs RB26

To help ensure you get the most out of your D series it is key to run a quality set of spark plugs. Spark plugs are responsible for sparking the combustion cycles that powers your engine.

With NGK spark plugs providing a hot reliable spark to ignite the air/fuel mixture in each cylinder your D series will run strong for many years to come.

Below is a list of the best NGK spark plugs for the D15 and D16 Vtec engines. These iridium core plugs are available in 4 popular heat ranges to suit any D series engine build.

To make things easy we have listed out the correct NGK spark plug based on horsepower output from your Honda D-series. If you have any questions feel free to comment below or give us a call.

Honda D16 spark plugs

Iridium core NGK plugs are an easy bolt-in upgrade, the BKR6eix-11 in the part number means the plugs come pre-gapped to 1.1mm perfect for NA builds.

BKR7eix (no -11) are gapped to 0.9mm perfect for ensuring a reliable spark under high boost conditions.

If you find you need to a gap the plugs down tighter you should consider upgrading your ignition coils to either the R35 coilsHaltech IGN1 coils or AEM IGN1 smart coils.


Iridium core plugs hold up to heat better and last longer than their copper core brothers such as the NGK bkr7e spark plugs. For these 2 reasons you can find the Iridium core NGK plugs in everything from our purpose-built Honda powered track cars to turbo street cars.

Velocity Element RB26 turbo manifold dyno testing

Spark Blow Out

Any high power D series engine makes its power through high cylinder pressures. As boost increases so do the cylinder pressures. These high pressures put the spark plug and ignition coil to the test.

As spark plugs wear out the resistance increases, this increased resistance combined with high cylinder pressures results in “spark blow out” and power loss. Spark blow out is a situation where the spark fails to arc from the spark plug’s electrode to the grounding strap causing a misfire and major loss of power.

Running the correct NGK iridium plugs for your particular D series helps to ensure your engine will not suffer from spark blow out even under high boost/high cylinder pressures situations.

NGK iridium plugs have proven to last longer and perform better than any other spark plug option on the market both on and off the race track.

D15 & D16 NGK Spark Plugs (Copper core)

For the best possible performance we do always recommend running an Iridium core NGK spark plug in the Vtec D-series engines.

However we also offer copper core NGK spark plugs for all Honda D series engines. Copper core plugs are the OEM spec plug for the D15/D16 and do work well just not as good as the Iridium core NGK plugs.

As mentioned above the life span of the a copper core spark plug will be MUCH shorter than that of an Iridium core plug. The copper core plugs will also need to be “gapped down” (tighter/smaller gap) for any D series engine running with a turbo or supercharger setup.

The upside of the copper core NGK spark plugs is they are VERY affordable/budget friendly.

D-series Vtec NGK Copper Core Spark plugs:

Stock – 200hp BKR6E Spark Plug
200-350hp BKR7E Spark Plug
350hp + BKR8eix-11 (For any Turbo D series engine making 500+ whp we highly recommend running Iridium core plugs. At this power level the copper core plugs will not last long and will end up causing spark blow out issues/loss of power. Using the correct Iridium plug and a good set of ignition coils is key to reliably making over 100HP per cylinder.)

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