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 Rubbing up the wrong way?

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Trevor Amos

Number of posts : 875
Registration date : 2010-08-13

PostSubject: Rubbing up the wrong way?   Sat Apr 25, 2015 7:07 am

Here is a thought, or two!
Power absorption from the effects of friction?

It is generally acknowledged that 15% of available power measured at the crank of an engine is taken by friction, and of that figure anything up to 20% is piston-ring friction. As most Bantams run with just a single narrow ring perhaps we can perhaps safely reduce that to 15%.

The swept area of a 64 x 58 cylinder calculates out at 116 sq cm, with the 54 x 54 at 91.6 sq cm; so the larger 186 engine cylinder has 27% greater friction area than the 125 engine!
Because of the larger and heavier piston, con-rod and crank discs of the 186, all of the bearings are under greater reciprocation forces producing heavier loading, so consequently more friction.

Within the engineering world of rotating bearings, losses are generally described as being .001 of the applied load. Whatever way you may calculate that factor out, eliminating one crank support bearing contributes an infinitesimal reduction in rotational friction in a Bantam engine. With the crank loads now being taken by only two bearings the resultant of mean friction loading is greater for each of the remaining bearings. Which then could lead to an overall increase in friction?

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Number of posts : 79
Age : 71
Localisation : SUNNY BARWELL
Registration date : 2014-07-31

PostSubject: ..................*TOTALLY LOGICAL*....................   Sat Apr 25, 2015 3:43 pm

Good Morning Trevor and All,

That sounds like commonsense to me!

Thank you for this great input to the ever- growing Bantam cause!

That will certainly work for all Bantams -Road Trials and Race!............ Very Happy

Have a Great Weekend!

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