Franklin O-405
# Franklin O-405

The Franklin O-405 (company designation 6AC-403) was an American air-cooled aircraft engine of the 1940s. The engine was of six-cylinder, horizontally-opposed layout and displaced 405 cu in (6.64 L). The power output was between 200 hp (149 kW) and 250 hp (186 kW) depending on variant. The O-405-9 (6ACV-403) was a vertically mounted, fan cooled version for helicopters.

## Variants

### 6AC-403 (XO-405-1)

    200 hp (149 kW) at 2,750 rpm

### 6ACSA-403 (XO-405-3)

    Supercharged, 220 hp (164 kW) at 2,750 rpm

### 6ACGSA-403 (O-405-5)

    Supercharged, geared propeller drive at 0.632:1. 250 hp (186 kW) at 3,200 rpm

### 6ACV-403 (O-405-9)

    Vertically mounted, fan-cooled helicopter version, 245 hp (183 kW) at 3,275 rpm

## Applications

* Culver XPQ-15
* Doman LZ-1A
* Doman Pelican
* Fairchild XUC-86B
* Fleetwings XBQ-1
* Kellett XR-8
* Sikorsky R-6

## Specifications (6AC-403/XO-405-1)

Data from

### General characteristics

* Type: 6-cylinder air-cooled horizontally opposed aircraft piston engine
* Bore: 4.625 in (117.5 mm)
* Stroke: 4.0 in (101.6 mm)
* Displacement: 403.2 in³ (6.6 L)
* Dry weight: 405 lb (184 kg)

### Components

* Cooling system: Air-cooled

### Performance

* Power output: 200 hp (149 kW) at 2,750 rpm
