1977 140hp bubble back

[micknjo]

Hi I have a 1977 140hp bubble back with a 13 1/4?17 prop on a picton 170gts that weighs about 500kg without the engine what sort of speed & fuel consumption should I expect from this set up

 

[bishopcherrycoke]

Re: 1977 140hp bubble back

I think you need a bigger prop. Keep an eye on your rps, you should be able to spin a bigger prop, unless you carry alot of weight. A good rule o thumb is take your horse power and divide it by 10. So if you ran your boat at wot for 1 hour, you would burn 14 gallons of fuel. it's not always 100%, but it will get you close without any testing.

 

[emdsapmgr]

Re: 1977 140hp bubble back

Years ago-when engines shipped from the factory with propellers-yours would have shipped with a 13 X 21 prop. (Even though that may not be the exact one you needed for your application.)