5-inch FPV racing motor
EMAX RSIII 2306
A 5-inch racing motor: 2306 stator, titanium alloy shaft, N54SH magnets, 27.8 g without leads, and up to 1,980 g of pull per motor on EMAX’s 6S bench (2100KV).
- 5-inch racing
- 6S (1800KV, 2100KV) or 4S (2500KV)
- 5-inch props
The spin is an illustration: the model turns at 1/600 of the no-load speed, and it is a generic 2306 motor drawn from EMAX’s published sizes, not its exact design. No-load speed is KV × 22.2 V, a nominal pack for this version. EMAX’s bench tables for it step by thrust rather than throttle, so they are in the bench data below, not on this readout.
- Max thrust
- 1,980 g
- HQ 5×4.8×3 prop, 25.2 V
- Weight
- 27.8 g
- without leads; 1800KV 27.9 g, 2500KV 27.7 g
- Peak current
- 41.8 A
- full throttle
- Max power
- 1,053 W
- full throttle
from $19.99a motor at EMAX USA
A set of four: $79.96
Price seen Oct 19, 2026. Plain links: we earn nothing from them.
What you get for $19.99
About 2 kg of pull on 6S
On EMAX’s 25.2 V bench the 2100KV pulled 1,980 g at full throttle on an HQ 5 × 4.8 × 3, drawing 41.8 A.
Source: EMAX 2100KV payload test
27.8 g
EMAX lists 27.7–27.9 g without leads, depending on the KV, against 29.3 g for the RSIII 2207.
Source: EMAX spec sheet, EMAX product page
Titanium alloy shaft
A 4 mm titanium alloy shaft with an M5 prop thread; EMAX USA says titanium is stronger and lighter than steel.
Source: EMAX USA product page, EMAX product page, EMAX spec sheet
Rated for 150 °C
EMAX pairs N54SH magnets with single-strand wire rated for 240 °C, and rates the motor for 150 °C, with 180 °C as its maximum.
Source: EMAX USA product page
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 at 34 A (1800KV) and 46 A (2100KV) on 6S, and 43 A (2500KV) on 4S. On its bench the 2100KV drew up to 46.5 A and the 2500KV 47.9 A at full throttle, both on a DALPROP Cyclone 5050. An ESC rated for 50 A covers every prop EMAX tested. (EMAX spec sheet, EMAX 2100KV payload test, EMAX 2500KV payload test)
- Props
- EMAX lists 5 to 5.5-inch props for the 1800KV and 5-inch props for the 2100KV and 2500KV. On its 6S bench the 2100KV pulled 1,820–1,980 g at full throttle on five props, most on the HQ 5 × 4.8 × 3. (EMAX spec sheet, EMAX 2100KV payload test)
- Battery
- 6S for the 1800KV and 2100KV, 4S for the 2500KV. EMAX rates the first two for 3S–6S and the 2500KV for 3S–4S, and tested them at 25.2 V and 16.8 V. (EMAX spec sheet, EMAX 1800KV payload test, EMAX 2100KV payload test, EMAX 2500KV payload test)
- Frame
- Four M3 holes on a 16 mm circle (16 × 16 mm). (EMAX spec sheet)
Where to buy
- EMAX USAthe maker’s US store; one page for the 2207 and 2306, same price for every KV$19.99seen Oct 19, 2026Visit
- EMAXthe maker’s global store$30.78seen Oct 19, 2026Visit
- GetFPVchoose the KVprice on the store’s pageVisit
Plain links, not affiliate links. Prices change; the store’s page has the current one.
Full specs
| Spec | Value | Source |
|---|---|---|
| KV | 2,100 rpm/V (also 1800KV and 2500KV) | EMAX USA product page |
| Stator | 23 × 6 mm (2306) | EMAX spec sheet |
| Configuration | 12N14P (12 stator slots, 14 magnet poles) | EMAX spec sheet |
| Battery | 3S–6S LiPo (1800KV, 2100KV); 3S–4S (2500KV) | EMAX spec sheet |
| Weight | 27.8 g (without leads; 1800KV 27.9 g, 2500KV 27.7 g) | EMAX spec sheet |
| Dimensions | φ27.3 × 32 mm (with shaft); 25.1 mm from the bottom of the bell to the shaft tip | EMAX spec sheet |
| Shaft | Titanium alloy, M5 thread, protrudes 12.9 mm; 4 mm through the bearings | EMAX spec sheet, EMAX USA product page, EMAX product page |
| Mounting | 4 × M3 holes on a 16 mm circle (16 × 16 mm) | EMAX spec sheet |
| Bell | 7075 aluminium | EMAX USA product page |
| Magnets | N54SH neodymium magnets | EMAX USA product page |
| Bearings | G1-grade high-speed bearings (EMAX gives no size) | EMAX USA product page |
| Winding | Single-strand, AIW enamelled copper wire rated for 240 °C | EMAX USA product page |
| Internal resistance | 57 mΩ (1800KV 68 mΩ, 2500KV 43 mΩ) | EMAX spec sheet |
| Idle current | 1.4 A (at 10 V; 1800KV 1.1 A, 2500KV 1.8 A) | EMAX spec sheet |
| Peak current | 46 A (on 6S; 1800KV 34 A on 6S, 2500KV 43 A on 4S) | EMAX spec sheet |
| Max power | 1,160 W (on 6S; 1800KV 860 W on 6S, 2500KV 720 W on 4S) | EMAX spec sheet |
| Leads | 20 AWG, 120 mm | EMAX spec sheet |
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.
1800KV on 6S, 25.2 V6 props
| Prop | Step | Current (A) | Thrust (g) | Power (W) | Efficiency (g/W) |
|---|---|---|---|---|---|
| HQ 5×4.8×3 | 2.8 | 300 | 70.56 | 4.25 | |
| 5.6 | 500 | 141.12 | 3.54 | ||
| 9.2 | 700 | 231.84 | 3.02 | ||
| Max | 34.1 | 1,780 | 859.32 | 2.07 | |
| DALPROP Cyclone 5050 | 2.9 | 300 | 73.08 | 4.11 | |
| 5.8 | 500 | 146.16 | 3.42 | ||
| 9.8 | 700 | 246.96 | 2.83 | ||
| Max | 33.5 | 1,730 | 844.2 | 2.05 | |
| HQ 5×4.3×3 | 2.8 | 300 | 70.56 | 4.25 | |
| 5.5 | 500 | 138.6 | 3.61 | ||
| 8.9 | 700 | 224.28 | 3.12 | ||
| Max | 29.8 | 1,720 | 750.96 | 2.29 | |
| DALPROP Cyclone 5046 | 3 | 300 | 75.6 | 3.97 | |
| 5.8 | 500 | 146.16 | 3.42 | ||
| 9.6 | 700 | 241.92 | 2.89 | ||
| Max | 32.5 | 1,700 | 819 | 2.08 | |
| DALPROP Cyclone 5040 | 2.9 | 300 | 73.08 | 4.11 | |
| 5.6 | 500 | 141.12 | 3.54 | ||
| 9 | 700 | 226.8 | 3.09 | ||
| Max | 27.9 | 1,680 | 703.08 | 2.39 | |
| GF 5045-3 | 2.8 | 300 | 70.56 | 4.25 | |
| 5.6 | 500 | 141.12 | 3.54 | ||
| 9 | 700 | 226.8 | 3.09 | ||
| Max | 30.6 | 1,670 | 771.12 | 2.17 |
Source: EMAX 1800KV payload test
2100KV on 6S, 25.2 V5 props
| Prop | Step | Current (A) | Thrust (g) | Power (W) | Efficiency (g/W) |
|---|---|---|---|---|---|
| HQ 5×4.8×3 | 2.9 | 300 | 73.08 | 4.11 | |
| 5.9 | 500 | 148.68 | 3.36 | ||
| 9.7 | 700 | 244.44 | 2.86 | ||
| Max | 41.8 | 1,980 | 1053.36 | 1.88 | |
| DALPROP Cyclone 5046 | 3 | 300 | 75.6 | 3.97 | |
| 5.9 | 500 | 148.68 | 3.36 | ||
| 9.9 | 700 | 249.48 | 2.81 | ||
| Max | 46.2 | 1,960 | 1164.24 | 1.68 | |
| DALPROP Cyclone 5050 | 3.1 | 300 | 78.12 | 3.84 | |
| 6.2 | 500 | 156.24 | 3.2 | ||
| 10.1 | 700 | 254.52 | 2.75 | ||
| Max | 46.5 | 1,920 | 1171.8 | 1.64 | |
| GF 5045-3 | 3 | 300 | 75.6 | 3.97 | |
| 5.9 | 500 | 148.68 | 3.36 | ||
| 9.6 | 700 | 241.92 | 2.89 | ||
| Max | 37.7 | 1,830 | 950.04 | 1.93 | |
| DALPROP Cyclone 5040 | 3.1 | 300 | 78.12 | 3.84 | |
| 5.9 | 500 | 148.68 | 3.36 | ||
| 9.7 | 700 | 244.44 | 2.86 | ||
| Max | 36.1 | 1,820 | 909.72 | 2 |
Source: EMAX 2100KV payload test
2500KV on 4S, 16.8 V6 props
| Prop | Step | Current (A) | Thrust (g) | Power (W) | Efficiency (g/W) |
|---|---|---|---|---|---|
| DALPROP Cyclone 5050 | 4.5 | 300 | 75.6 | 3.97 | |
| 9.2 | 500 | 154.56 | 3.23 | ||
| 15.2 | 700 | 255.36 | 2.74 | ||
| Max | 47.9 | 1,590 | 804.72 | 1.98 | |
| DALPROP Cyclone 5046 | 4.5 | 300 | 75.6 | 3.97 | |
| 8.9 | 500 | 149.52 | 3.34 | ||
| 14.3 | 700 | 240.24 | 2.91 | ||
| Max | 43.1 | 1,580 | 724.08 | 2.18 | |
| HQ 5×4.8×3 | 4.4 | 300 | 73.92 | 4.06 | |
| 8.7 | 500 | 146.16 | 3.42 | ||
| 13.9 | 700 | 233.52 | 3 | ||
| Max | 41.9 | 1,580 | 703.92 | 2.24 | |
| HQ 5×4.3×3 | 4.3 | 300 | 72.24 | 4.15 | |
| 8.5 | 500 | 142.8 | 3.5 | ||
| 13.4 | 700 | 225.12 | 3.11 | ||
| Max | 36.5 | 1,480 | 613.2 | 2.41 | |
| GF 5045-3 | 4.3 | 300 | 72.24 | 4.15 | |
| 8.7 | 500 | 146.16 | 3.42 | ||
| 13.7 | 700 | 230.16 | 3.04 | ||
| Max | 36.8 | 1,470 | 618.24 | 2.38 | |
| DALPROP Cyclone 5040 | 4.4 | 300 | 73.92 | 4.06 | |
| 8.7 | 500 | 146.16 | 3.42 | ||
| 13.6 | 700 | 228.48 | 3.06 | ||
| Max | 35.1 | 1,410 | 589.68 | 2.39 |
Source: EMAX 2500KV payload test
Inside the motor
A brushless outrunner: the coils stand still in the middle and the magnets spin around them. From the top down:
- Shaft. Titanium alloy, M5 thread, protrudes 12.9 mm; 4 mm through the bearings. (EMAX spec sheet, EMAX USA product page, EMAX product page)
- Bell. 7075 aluminium. (EMAX USA product page)
- Magnets. N54SH neodymium magnets. (EMAX USA product page)
- Stator. The coils are wound on a stack of thin steel laminations: 23 × 6 mm (2306). (EMAX spec sheet)
- Winding. Single-strand, AIW enamelled copper wire rated for 240 °C. (EMAX USA product page)
- Bearings. G1-grade high-speed bearings (EMAX gives no size). (EMAX USA product page)
- Base. 4 × M3 holes on a 16 mm circle (16 × 16 mm). (EMAX spec sheet)
How fast it spins
KV is the motor’s no-load speed per volt. With nothing on the shaft, the 2100KV 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.
| Battery | Volts | No-load rpm (KV × V) | Electrical frequency | ESC steps per second |
|---|---|---|---|---|
| 4S nominal | 14.8 | 31,080 | 3,626 Hz | 21,756 |
| 4S full | 16.8 | 35,280 | 4,116 Hz | 24,696 |
| 6S nominal | 22.2 | 46,620 | 5,439 Hz | 32,634 |
| 6S full | 25.2 | 52,920 | 6,174 Hz | 37,044 |
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 23 × 6 mm stator, 27.3 mm bell, 19.1 mm height, 5 mm shaft, 16 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
- EMAX USA: RSIII Brushless FPV Racing Motor (product page for the 2207 and 2306, with its materials list). Retrieved Oct 19, 2026.
- EMAX: RSIII 2306 FPV Racing motor, 1800KV 2100KV 2500KV (product page on EMAX’s global store, with EMAX’s RSIII infographics). Retrieved Oct 19, 2026.
- EMAX: RSIII-2306 spec sheet (dimension drawing and spec table for each KV; image on EMAX’s product page). Retrieved Oct 19, 2026.
- EMAX: RSIII2306 1800KV payload test at 25.2 V, six props (image on EMAX’s product page). Steps of 300, 500 and 700 g, then “Max” at full throttle; EMAX’s rpm column is left out because it has no figure at full throttle.. Retrieved Oct 19, 2026.
- EMAX: RSIII2306 2100KV payload test at 25.2 V, five props (image on EMAX’s product page). Steps of 300, 500 and 700 g, then “Max” at full throttle; EMAX’s rpm column is left out because it has no figure at full throttle.. Retrieved Oct 19, 2026.
- EMAX: RSIII2306 2500KV payload test at 16.8 V, six props (image on EMAX’s product page). Steps of 300, 500 and 700 g, then “Max” at full throttle; EMAX’s rpm column is left out because it has no figure at full throttle.. Retrieved Oct 19, 2026.