Re: Fuel consumption on 115 OMC
Welcome to iboats!!<br /><br />Lets start at the beginning. Whats the model number of the motor you have now? There wasnt a 115 in 87 but there was a 110, which is basically the same thing. Assuming thats what you have, and further assuming your old 110 was an OMC crossflow, theyre identical.<br /><br />However, the weight and drag difference between the 2 boats is a lot. There will be some differences there. IE -- we would suspect that you used a much larger pitch on the smaller, lighter aluminum boat. That alone would account for some distance per gallon of fuel.<br /><br />As for the present set up, 5500 with a 17" prop isnt quite what we have seen on that boat. You didnt say which model 18' Mako but we usually end up with a 19" prop on a crossflow set up at or near 5800 on the flats boat style model. <br /><br />While we dont suspect your Mako will ever get the fuel mileage the aluminum boat did (with the same motor), I agree with OB's observations on general fuel consumption. At wide open you should be looking at about 11 gallons an hour. It seems youre way past that so something is wrong.<br /><br />As OB suggested lets see if this motor is healthy. Look at the things he suggested and also compression, timing and linkage (make sure everything is going to WOT). Also tell us more about the set up. What kind of prop? Do you have a jackplate? Is it indeed the Mako flats boat?
