Seth said:
Does it make much of a difference in fuel economy when you go from say a 90/65 up to a 150/105 or bigger? My buddy said that anything over a 90/65 will kill your fuel economy, even on the newer Etec's and Optimax's.
I don't think Im getting very good fuel economy out of my older 2 stroke 50hp Yamaha anyways so it probably wouldn't be enough to matter to me but I was just curious.
This is a tough question because if you’re interested in the best fuel consumption you must accurately match motor size to the boat and/or load you intend on pushing. I would always choose the most HP you can…what your boat is rated for. Though a slightly larger engine may burn more fuel it will not work nearly as hard as the smaller motor.
I’ll also tell you (within some limits) that a local boat dealer will get your custom built aluminum hull badged with whatever HP rating you want…that is if he thinks he can sell you a bigger motor.
There is no doubt…assuming you are comparing engines with similar ignition & fuel control systems the larger engine will burn more fuel than a smaller engine. Engine HP output is the direct result of the size/energy of the air/fuel combustion occurring…bigger volume, bigger combustion =’s bigger air intake/exhaust and more fuel burned.
Comparing older carbureted 2-stroke vs newer 2-stroke or 4-stroke w/computer controlled fuel injection. No question the fuel injected will burn less than the carbureted. I’d say this may be true even with rather large HP differences…i.e. carbureted 50hp vs. fuel injected 90.
You should consider that multiple HP offerings from the same manufacture may utilize the same power head. For example, 40 - 60 may be the same power head…75 – 115 may be another…135 – 175 another…200 – 250 another…so on so forth. Within each family, though the larger will burn more fuel, the fuel usage (gallons/hr) will be relatively close.
This why in the other thread I recommended the smaller 56” width given your motor choice. A 150hp on a 56” bottom is ideal….good speed and fuel consumption. If you are leaning towards the 90 then I would consider a 52” bottom width. I rarely see 60” boats…unless given special need.
For what ever reason my 96 model 1852 was only rated for a 50hp. I was so close to swapping the badge for a 90hp, or even a 150hp, badge but this got a little “iffy” finding a manufacturer to do it. So I chose to stay within the limits Johnny Law has set for me and went with the 60/40.
