Large block extra 0.5 or 1HP

[Hinchy1964]

Hi

Does any of the gurus out there know where the extra 0.5 or 1hp came from quoted by British Seagull

Some are 4HP and some are quoted as 4.5HP and some 5HP. I know members have said that in reality the HP is way below that but they must have had some calculations to back it up.

CC's seem to be the same so was it the stroke, different cam shape, ignition, port shape, port timing, carburation, gearing ratio

Just curious

Ian

[Horsley-Anarak]

Hi

different cam shape

Ian

It won't be that, 2 stroke engines do not have camshafts.

I think that the HP values are all pie in the sky.

All the ones I have taken apart have been very similar, some built 30 years apart are almost identical.

I am sure the gurus will know more.

H-A

[Charles uk]

The power figures quoted by British Seagull in their glory days were "perceived hp"
i.e. their propulsive output was comparible to someone elses 3, 4 or 5 hp outboard.

So all the difference was provided by the gearbox & propeller, larger diameter slower turning props give greater propulsive power for the same powerhead output.

There is no difference between the power head output in any specific years Featherweight & 40+, & the same applies to the Centurys & Century +.

[Hinchy1964]

Ah ha this was the conclusion I had come to. Hence my 11" prop giving a little more propulsion.

Thanks that makes sense as I cant see any differences either.

Thanks

Ian