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RPM = Fuel consumption?


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Who knows the relationship between weight, rpm and gas consumption? A little difference or is it huge?

Also, speaking of gas, the book will likely recommend 89 octane for this '04 HammerHead motor. But with fuel injection and anti-knock sensor why not run 87 if boat is not having trouble with it? Any one?

Any inexpensive fuel flow meters that would be recommended to install?



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The more direct relationship is throttle position to RPM. I can hit top speed and the rev limiter at 1/4 throttle unloaded but need more than 3/4 throttle with a full load of people. Same applies for wakeboard speeds, ski speeds etc. And there is the rate of change of throttle position. I.e the faster you jam the throttle the more fuel you will use.

It is obvious for the same speeds more weight will mean more consumption (shown by throttle position). I'm nearly full throttle with all the factory ballast and added bags full while wakeboarding.

As for running lower octane... not worth the difference in cost... a knock sensor is reactive.... you have to have knocking before it retards the timing. Damage is happening then it retards, it all happens in a split second (you won't know it is knocking unless it is extreme) but it will add up. Use at least the recommended octane rating

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Rich it is all about the speed, RPM and the weight. The more weight the faster you run the more gas you are going to use. Pull your kids around on a tube you will not use much fuel. Pull the on skis or boards and the fuel will change.

I'm with G-Mack use the best fuel you can afford. The higher the octane the more advanced your motor will run, hence will run cleaner, better and more efficient.

Welcome to the crew.

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Thanks guys. Like the observation about throttle position and both of your suggestions to stay with high octane fuel. I fly so know the manifold gage but mostly to elevation changing power. But of course in the end it cost whatever it cost to run the boat... not like we are going to stop:))

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That's the best answer - you're not going to stop no matter the cost. My father in law asks me about octane and fuel consumption on my boat. My answer is that if I can't afford the difference to go the higher grade, I probably shouldn't have bought the boat.

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