EMAX ECO II 2004

What it pulls

EMAX’s own bench test, one line per prop. Drag across the chart to move the throttle; the model above follows.

What you get for $13.40

• 16.4 g

  16.4 g without leads for the 2400KV and 3000KV, 16.6 g for the 1600KV and 2000KV.

  Source: EMAX spec sheet

• 864 g on a 5-inch prop at 16 V

  On EMAX’s 16 V bench the 2400KV pulled 864 g at full throttle on an EMAX Avan 5120, drawing 21.8 A.

  Source: EMAX 2400KV thrust tables

• N52SH arc magnets

  Curved N52SH magnets in place of the N48 magnets EMAX used before; EMAX says they allow a tighter air gap.

  Source: EMAX USA product page

• NSK bearings, 7075 base

  NSK precision bearings, a steel shaft and a 7075 aluminium base casing.

  Source: EMAX spec sheet

What to pair it with

Our reading of EMAX’s numbers, so your build matches what the motor was tested with.

ESC

EMAX rates the peak current on 6S at 18 A (1600KV), 23 A (2000KV), 25 A (2400KV) and 32 A (3000KV). Its bench tests peaked at 21.8 A for the 2400KV and 31.6 A for the 3000KV, both on an Avan 5120 at 16 V. A 30 A ESC covers the 1600KV to 2400KV; for the 3000KV, choose one rated for at least 32 A. (EMAX spec tables, EMAX 2400KV thrust tables, EMAX 3000KV thrust tables)

Props

EMAX lists 4 to 5-inch props for the 1600KV to 2400KV and 3 to 5-inch for the 3000KV. At 16 V the 2400KV pulled 864 g on an EMAX Avan 5120 and 850 g on a Gemfan SL5125; at 24 V it pulled 930 g on a Gemfan 4023. (EMAX spec tables, EMAX 2400KV thrust tables)

Battery

EMAX rates the 1600KV, 2000KV and 2400KV for 4S–6S and the 3000KV for 3S–6S. Its bench tests ran at 16 V, 22.2 V and 24 V. (EMAX spec sheet, EMAX 1600KV thrust tables, EMAX 2000KV thrust tables, EMAX 2400KV thrust tables, EMAX 3000KV thrust tables)

Frame

Four M2 holes on a 12 mm circle (12 × 12 mm), which EMAX says fits toothpick-style 5-inch frames and 3–4-inch cinewhoop frames. M2 screws in 6, 7.5 and 8.5 mm lengths come in the box. (EMAX spec sheet, EMAX USA product page)

Where to buy

• EMAX USAthe maker’s store; same price for every KV
  $13.40seen Oct 19, 2026
  Visit
• RaceDayQuads2400KV
  price on the store’s page
  Visit
• Pyrodrone2400KV
  price on the store’s page
  Visit
• WREKDchoose the KV
  price on the store’s page
  Visit
• NewBeeDrone2400KV
  price on the store’s page
  Visit

Plain links, not affiliate links. Prices change; the store’s page has the current one.

Full specs

Bench data

Redrawn from EMAX’s test reports. Thrust is static pull on a bench, more than you get in flight. Power is volts × amps; efficiency is thrust divided by power.

Inside the motor

A brushless outrunner: the coils stand still in the middle and the magnets spin around them. From the top down:

• Shaft. Steel; 1.5 mm prop-adapter shaft protruding 4.5 mm; 3 mm through the bearings. (EMAX spec sheet)
• Bell. Rounded, fully mirror-polished, with stronger attachment points; four M2 holes in the top for the prop. (EMAX USA product page, EMAX spec sheet)
• Magnets. N52SH curved arc magnets (EMAX says they replace the N48 magnets it used before and allow a tighter air gap). (EMAX USA product page)
• Stator. The coils are wound on a stack of thin steel laminations: 20 × 4 mm (2004). (EMAX USA product page)
• Winding. Multi-strand. (EMAX spec sheet)
• Bearings. NSK precision bearings. (EMAX spec sheet)
• Base. 4 × M2 holes on a 12 mm circle (12 × 12 mm); base casing 7075 aluminium. (EMAX spec sheet)

How fast it spins

KV is the motor’s no-load speed per volt. With nothing on the shaft, the 2400KV version reaches about these speeds; a prop loads the motor and brings it down, typically to around 70–75% of these figures at full throttle.

A 14-pole rotor has 7 pole pairs, so every turn of the shaft is 7 electrical cycles, and a six-step ESC switches the phases 42 times per turn.

About the 3D model

A generic outrunner drawn from EMAX’s published sizes: the 20 × 4 mm stator, 24.7 mm bell, 14.7 mm height, 1.5 mm shaft, 12 mm mounting circle and 12 teeth and 14 magnets. Anything EMAX doesn’t publish is typical for a motor this size, and the bell’s spoked top, the base and the inside are a generic design, not this motor’s. The colours are read off the maker’s product photos. There are no logos or markings: it is our drawing, not the maker’s.

Sources

1. EMAX USA: ECO II 2004 Brushless Motor (product page). Retrieved Oct 19, 2026.
2. EMAX: ECO II Series 2004 1600KV 2000KV 2400KV 3000KV (product page on EMAX’s global store). Retrieved Oct 19, 2026.
3. EMAX: ECO II 2004 spec sheet (dimension drawing, specifications, features and box contents; image on EMAX’s product pages). Retrieved Oct 19, 2026.
4. EMAX: ECO II 2004 spec tables for each KV (image on EMAX’s product page). Retrieved Oct 19, 2026.
5. EMAX: ECO II 2004 1600KV thrust tables at 24 V, four props (image on EMAX’s product page). Throttle 40–90% in 10% steps, then EMAX’s “Max”, entered here as 100%. EMAX’s rpm column is left out because most of its tables give no rpm at full throttle.. Retrieved Oct 19, 2026.
6. EMAX: ECO II 2004 2000KV thrust tables at 16 V and 24 V, five tests (image on EMAX’s product page). Throttle 40–90% in 10% steps, then EMAX’s “Max”, entered here as 100%. EMAX’s rpm column is left out because most of its tables give no rpm at full throttle.. Retrieved Oct 19, 2026.
7. EMAX: ECO II 2004 2400KV thrust tables at 16 V and 24 V, five tests (image on EMAX’s product page). Throttle 40–90% in 10% steps, then EMAX’s “Max”, entered here as 100%. EMAX’s rpm column is left out because most of its tables give no rpm at full throttle.. Retrieved Oct 19, 2026.
8. EMAX: ECO II 2004 3000KV thrust tables at 22.2 V and 16 V, four tests (image on EMAX’s product page). Throttle 40–90% in 10% steps, then EMAX’s “Max”, entered here as 100%. EMAX’s rpm column is left out because most of its tables give no rpm at full throttle.. Retrieved Oct 19, 2026.