I'm trying to get an idea of what kind of fuel consumption I will be using on my 86 panther with twin 380hp FI 454 mags.
Any input on similar setups would be great.


With a 150g tank, I am sure even at cruise I would be getting less than a gallon per mile?

I have a friend who had a scarab 300 with 454 365hp but they where carburated motors (quadrajets). Boat had TRS drives with 23P Mirage props and it seemed to cruise best around 3000-3200rpm wich was maybe 35-40 mph and it was realy easy on gas at that speed. I remember throwing 30gal of gas in it in the morning, cruising around stoping to swim a few times all day and still having more gas in the boat than before we added the 30gal. I dont know exactly but I would say he was geting easly 1.5 mpg proubably closer to 2 mpg. I do know from experience quadrajets can return great fuel milage aslong as you take it easy on the throtels. I have a boat with Merc 454 mag mpi 385hp motors and I think they are harder on fuel than the carburated motors. Even when trying I cant get 1mpg but then again the boat weighs proubably more than 13000 with fuel and gear wich is almost twice what a panther weighs. My point is I dont think you will get 2mpg but I would think 1.5 should not be a proublem at around 3000rpm

Thats great information. Thanks. 40gph is actually much better than I was hoping. I'm also running trs drives. THe broschure said the boat was 6400, which I assume is dry.

It's souonding more and more like I will have this boat out on the water a lot more than I thought this summer. Lots of river cruising trips, and the occasion fly by through portland lol.

From looking at a lot of boat reviews, I have observed that almost all gasoline boats get between 1-2 mpg at cruise speed. It does not matter if it is a 4 cylinder or a 1075.

When my Panther had twin Merc 425's I would get roughly 1mpg at ~3600RPM 47mph.
25" Quicksilver 3blades
Not so much now...

funny
I ran my old Sonic out of gas n Lake Erie one time after modifying the motors. Never even thought about it. Same trip I'd done a 100 times and always came home w/a 1/4 tank of fuel.
This time I was 20 mls form the trailer and down to an 1/8 of a tank.