The formula that works best only applies to the small newer normally aspirated (carbureted) 4 cycle engines. The ratios change slightly worse with altitude and slightly better with fuel injection and tuning. Most American mowers and the newer 4 cycle outboard motors fit into one of these two formulas: Typical new carbureted engine well tuned: 1 x HP per each 25 cc Fuel injected: 1 x HP per each 22 cc Notes:-Most engines are tuned down to a lower HP for better engine life. -It is common for the same cc engine to be built in 3 different HP versions with the highest rated being the maximized HP per cc version. That is how you see price and HP changes on the same cc engine made by the same company. -Some of the newest (2008 and newer) engines from Japan perform slightly better. A typical 150cc motor should equate to between 3.5 - 6 HP+ depending on tuning with 5 HP being the adv.
The actual formula plots as a curve and is not linear and also does not apply to Max/High Performance engines like motorcycles.
5.5 hp
very hard to convert, about 2.5-3.5hp per 100 cc in mowers
88.74
9 HP
You can't. 123 cc is a volume, horse power is power. If you know the output of a 123 cc engine, either (i) you already know its horsepower, or (ii) you convert kilowatts to horsepower by hp = kw/0.746.
you can convert cubic inches to cc's but not horse power. an engine with say 65 cc's can have different amounts of horse power depending on carberation, pistons, valves etc. etc. etc. but my 65 cc engine does have 1.89 hp if that helps.
мотокультиватор expert 139cc
You don't. cc is the size of the engine. It cannot specify the h.p. which is variable.
No.
21.5
I bought a 208 cc snowblower , how many horsepower is that ?
Displacement doesn't directly equivocate to horsepower.