It has been suggested to open another thread specific for the conversion of the Briggs & Stratton 49-series of vertical shaft engines to an economical and reliable aircraft engine. So here it is
The Briggs & Stratton 49-series family currently (2019) consists of 4 streams of engines:
Suitable engines are the Professional & the Vanguard series, with 1 1/8" crankshaft (28.5mm).
General specifications:
Bore: 83.81mm (3.3")
Stroke: 73.41mm (2.89")
Displacement: 810cm3 (49ci)
Mixture: 1 twin-barrel Nikki carburetor (28mm throat, 22mm ventury), throttle body injector system on EFI model with O2 sensor
Lubrication: full pressure with full-flow filter and oil cooler
Power: from 24 to 28 (older versions to 30hp)
Weight: generally around 40kg complete, 41.5kg with the big external airfilter
Major advantage over other engines: forged crankshaft, forged alu conrods, built-up camshaft (not cast iron), automotive-style pistons and plated EX valve (Vanguard only). This results in stronger components in critical areas
The B&S 49-series is currently the best value, lowest weight and best quality engine for a 33 to 35hp (maybe up to 37hp with some more work) direct-drive engine conversion to be used in a single-seat very light aircraft. The complete engine without fluids is around 32kg, which is comparable to a Rotax 377, Kawasaki 440 and definitely a lot lighter than a 1/2 VW or the Citroen 2CV. This engine is now the most suitable engine option (called the SE-33) for the Spacek SD-1 Minisport, developped by Igor Spacek.
To achieve a successful conversion from vertical shaft to horizontal shaft, an engineering analysis is required to identify and address the areas affected by turning the engine. Spacek has elected to turn the engine with the heads up as that fitted in with the other engine option, a horizontal engine from a B&S competitor (can't name them, their lawyer is watching but the engine model is a CH750).
I have elected to turn my engine up-side-down (after all, I live down-under), meaning heads down. I'm doing this for a number of reasons:
In my case, the oil pump is below the crankshaft but the "sump" would be in the cylinder heads (lowest points). The "easy" solution is to install a dry-sump system with the normal oil level at the pump height.
to be continued
The Briggs & Stratton 49-series family currently (2019) consists of 4 streams of engines:
- Commercial series (49T, 26 & 27hp)
- Professional series (49S, 26 & 27hp)
- Vanguard series (49V and 49R, 24 & 26hp)
- Vanguard EFI series (49E, 24 & 28hp)
Suitable engines are the Professional & the Vanguard series, with 1 1/8" crankshaft (28.5mm).
General specifications:
Bore: 83.81mm (3.3")
Stroke: 73.41mm (2.89")
Displacement: 810cm3 (49ci)
Mixture: 1 twin-barrel Nikki carburetor (28mm throat, 22mm ventury), throttle body injector system on EFI model with O2 sensor
Lubrication: full pressure with full-flow filter and oil cooler
Power: from 24 to 28 (older versions to 30hp)
Weight: generally around 40kg complete, 41.5kg with the big external airfilter
Major advantage over other engines: forged crankshaft, forged alu conrods, built-up camshaft (not cast iron), automotive-style pistons and plated EX valve (Vanguard only). This results in stronger components in critical areas
The B&S 49-series is currently the best value, lowest weight and best quality engine for a 33 to 35hp (maybe up to 37hp with some more work) direct-drive engine conversion to be used in a single-seat very light aircraft. The complete engine without fluids is around 32kg, which is comparable to a Rotax 377, Kawasaki 440 and definitely a lot lighter than a 1/2 VW or the Citroen 2CV. This engine is now the most suitable engine option (called the SE-33) for the Spacek SD-1 Minisport, developped by Igor Spacek.
To achieve a successful conversion from vertical shaft to horizontal shaft, an engineering analysis is required to identify and address the areas affected by turning the engine. Spacek has elected to turn the engine with the heads up as that fitted in with the other engine option, a horizontal engine from a B&S competitor (can't name them, their lawyer is watching but the engine model is a CH750).
I have elected to turn my engine up-side-down (after all, I live down-under), meaning heads down. I'm doing this for a number of reasons:
- I don't like the bumps on top of the cowling for the cylinders or having the cylinders stick out
- the prop axis can be raised to the correct level and the cowling has a clean curve from the spinner to the fuel tank
- the oil pump is lower and easier to feed with oil
- cooling can be improved by having the air inlet further away from the spinner (higher velocity)
- the engine fits within the firewall outline (most streamlined installation)
In my case, the oil pump is below the crankshaft but the "sump" would be in the cylinder heads (lowest points). The "easy" solution is to install a dry-sump system with the normal oil level at the pump height.
to be continued
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