# How to read a Brisk spark plug reference

> Brisk's Identification System encodes the shell (thread, reach, hex, seat), resistor, heat range, spark-gap design, electrode material and gap. Here is how to decode it.

A Brisk code such as **DOR15YC-1** reads position by position: **shell** letter, optional **O** (special projection), **R/X** (resistor), **heat range**, spark-gap **design**, electrode **material**, then the **gap** suffix.

## 1. First letter — shell (thread, reach, hex & seat)

LetterThreadReachHexSeat
AM10×1.019 mm16gasket
BM12×1.2519 mm16gasket
DM14×1.2519 mm16gasket
FM18×1.511.2 mm21taper
GM14×1.2517.5 mm16taper
LM14×1.2519 mm21gasket
NM14×1.2512.7 mm21gasket
RM14×1.2525 mm16taper

(Other shells: C, E, H, J, K, M, NA, P, Q, S, T, U, X, 3V — same idea, each fixes a thread/reach/hex/seat combination.)

## 2. O — projection

An **O** after the shell letter marks a special metal-shell projection into the combustion chamber (still ISO-compliant).

## 3. R / X — interference suppression

- **R** — built-in interference-suppression resistor
- **X** — resistor reducing electrode burn-off
- none — no suppression

## 4. The number — heat range

The two digits are the **heat range**: **19 = hottest … 08 = coldest** (higher = hotter). It is relative to Brisk.

## 5. Spark-gap design

- **Y** projected insulator nose · **L** extremely projected
- **D** two electrodes · **T** three electrodes · **G** ring-shaped electrode
- **Z** two auxiliary electrodes + ring gap · **M** special design · none = not projected

## 6. Electrode material

- none — nickel alloy · **C** copper core · **E** copper core + yttrium
- **S** silver · **P** platinum · **IR** iridium

## 7. Spark gap (suffix)

**-1** = 1.0–1.1 mm, **-3** = 1.3 mm, **-5** = 1.5 mm, **-9** = 0.9 mm, none = 0.4–0.8 mm, **-T** = special.

## 8. Tightening torque

Torque depends on the seat, thread diameter and cylinder-head material. Flat seat (with gasket): 10 mm 10–15 N·m (iron) / 10–12 (alu), 12 mm 15–25 / 15–20, 14 mm 25–35 / 25–30, 18 mm 35–45 / 35–40. Taper seat: 12–14 mm 10–20 N·m, 18 mm 20–30. Always follow the value printed on the box.

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*Source : [How to read a Brisk spark plug reference](https://www.thesparktwin.com/en/guide/nomenclature-brisk/) — TheSparkTwin*