I have written in my Stihl 051 AV electronic Owner\'s manual that its horsepower is 5.8 hp at 7,000 rpm. I don\'t know if that is true for a Stihl 051 super. I have never heard of a Stihl 051 super.
The 056 was the original, the Super had a piston that was 2mm larger in diameter and an slight carburetor change. The Magnum had the same piston as the Super, but had a carburetor and ignition change, The one you did not ask about was the Magnum II (of which only 70 some were made) had a major carb change, a muffler change and an ignition change. It could be further modified in the muffler.
The 056 was made from the late 1970's to the mid 1980's.
That has no singular answer since there were the regular model, the Super and the Magnum. The stroke remained the same on all three at 38mm. The list is: 056 AVE 52mm x 38mm 056 AVSE 54mm x 38mm 056 AVSEQ 54mm x 38mm 056 Magnum AVE 56mm x 38mm 056 Magnum AVEQ 56mm x 38mm AV = anti-vibration or shock mounted E = electronic ignition S = Super Q = Quickstop or chainbrake
The Stihl 056 II features a 4.4 cubic inch (72 cc) engine with a power output of around 5.4 hp. It has a bore of 52 mm and a stroke of 38 mm, making it a robust and powerful chainsaw suitable for demanding tasks.
STIHL 029 SUPER 56.5CC 3.8HP
Stihl 029 super 56.5cc 3.8hp
92cc 7hp
The Stihl 036 Pro is 61.5cc with a 34mm stroke, 48mm bore, and makes 4.6 horsepower at 9500 rpm.
51.4cc
usually the super means a slightly larger displacement
68.7cc the super is 72