Originally Posted by two stroke mick
Please comment on this observations, are my figures for this calculation close to the the actual experances for this size of a rig?
Some good news they are a bit high actually
. (Rough formula is: 1 US Gallon per 10 hp per hour)
60hp Merc 2 stroke on a 5.2m Opsrey Sparrowhawk. Flak speed (5000 revs) 5 gallons an hour.
70 Hp Evinrude 2 stroke on Ribtec 535 at flak speed (5000 revs) 4 gallons an hour.
The Ex RNLI Evinrude swung a bigger prop than the merc and seemed to grip much better. Great little engine and as already mentioned I doubt you would save much by going 4 stroke. Honda et al will probably claim 30% savings at tickover, but if your only using 2lph at tickover thats hardly worth considering, and there has been some scary figures published for bigger 4 strokes running at speed.