Engines and capacities and capabilities

[RustyWreck]

Been looking through the net for engines upon engines........

Seen alkinds of stuff but what is good and what isnt .......

examples ...... 8.5bhp single yanmar ( good or not enough Bhp ) ?

twin tractor engine 1400 low top end revs 1400 but 40hp

Or Even a 5.5Bhp single diesel from a compressor with 3600rpm constant .....

is it the gearing you use or must it be the Bhp as a minimum ?


cheers

[Sphere]

Low rpm means a lot of shifting. And lots of gears means lots of space. 1400rpm doesn't sound practical to me.

[Stuart]

Ultimately the revs govern top speed. Unless you wanna go for the biggest single I'd go for something firing on every stroke for pulling power. 20hp plus. Car engines rev higher which is always good 1400 is too low to have any kind of fun and flexibility with it. Min revs you should consider is 3600.

[John]

Been looking through the net for engines upon engines........

Seen alkinds of stuff but what is good and what isnt .......

examples ...... 8.5bhp single yanmar ( good or not enough Bhp ) ?

twin tractor engine 1400 low top end revs 1400 but 40hp

Or Even a 5.5Bhp single diesel from a compressor with 3600rpm constant .....

is it the gearing you use or must it be the Bhp as a minimum ?


cheers

Only the bhp governs the bike's cruising speed & top speed. For the purposes of speed rating, the torque output & the revs are irrelevant. Whether the engine develops 8.5 bhp @ 1000 rpm or 10000 rpm, the speed appropriate for the bhp output will be the same. The difference will only be in the gearing, to allow the engine to reach rated power revs at the expected speed for the hp rating. The lower speed engine developing 10 times the torque of the high speed one to attain the same power with a tenth of the revs. The low bhp output of a small diesel single should not be a deterent, providing that expectations are reasonable & sensible. With 5.5 bhp, you should really be gearing the bike for no more than about 45 mph in top at 3600. For 8.5 bhp, about 55 mph. There is no point raising the gearing beyond that, for an expectation of a top speed that the engine will never pull, unless you drive off the end of Beachy Head! John.