fuel consumption on a 78 150hp

brianis

Petty Officer 3rd Class
Joined
Aug 3, 2011
Messages
89
so I just bought a 78 18 ft glasstron with a 2 stroke 150 hp im told they use a lot of fuel the po or way back po removed the stock tank and put 2 6 gallon tanks in it and we all know what its like to fuel up at the marina so im sure we will drive fast and enjoy it some but will be just cruising more being we have lakes and going to fish and my 5 yr old doesn't want to go fast all day so input should I maybe look into a bigger tank then 12 gallons. Im used to a 50 hp which never used fuel
 

jimbo_jwc

Ship Happens
Joined
Dec 19, 2010
Messages
633
Re: fuel consumption on a 78 150hp

011.jpgOld 1974 Chyrsler 120hp had 18 gal tank under bow and i carried 6 gal reserve . Fuel Mileage was porportionate to fun/speed /watersports and it sucked gas but ran like bat out of H_ll. I then tried a whale tail because they promised fuel savings and was suprised of the effect . I was tired of buying gas and twostroke oil buy the gallon . I lost the long bow lift on take off ,lost 1mph, and the taking too sharp of turns without blowing out prop wash . The fuel savings was the most impressive and never regreted as I think I was on my third gallon of oil when I stopped using . At the time it was one of the fastest boats around on 120Hp limited lakes . But hulls may not react the same . Mine was a cathredal hull / Like a trihull but deep V in middle made in Coral Gables Fla.it kinda looked like the Boat that was on the Flipper Show but open Bow and OB . My 2 Wheat Pennys Worth .
 

ezmobee

Supreme Mariner
Joined
Mar 26, 2007
Messages
23,767
Re: fuel consumption on a 78 150hp

Even if you're going to baby it I'd want an 18-20 gallon tank. If you're going to really use it, I'd probably want a 30. From what I understand those old V6 outboards really love the gas.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: fuel consumption on a 78 150hp

The 150 will use at least 15 gph(gallons per hour) at wot.(wide open throttle)
Of course less at a tame cruising speed.The best cruising speed is between just on plane and about 1000 rpm higher.
The boat will plane easier if you move some weight forward.I'm assuming you have the tanks and battery at the stern.
Before trying a hydrofoil(whale tail) check that the anti vent plate(just above the prop) is about even with the bottom of the transom. Trim down to help maintain speed at reduced throttle.The foil should help maintain low speed plane.
Be sure the motor is in excellent tune and the prop is good.If you get us the wot rpm and speed by gps we may be able to help with
your setup.The foil will slow your top speed and will increase top speed fuel use. Because it will take longer to get from here to there.
Something like smart tabs carefully applied,instead of a foil, will help hole shot, stay on plane, may handle better and may actually increase top speed.
 

Frank Acampora

Supreme Mariner
Joined
Jan 19, 2007
Messages
12,004
Re: fuel consumption on a 78 150hp

101_0006.jpg100_5942.jpg100_6197.JPG100_6202.JPG100_5946.jpg

Here is a 140 on a 21 foot cuddy. It has a 30 gallon tank and I am looking to get a bigger one.

12 gallons on your 150 is simply not going to go very far, especially if you start wakeboarding or skiing.
 

BonairII

Commander
Joined
Jun 7, 2011
Messages
2,727
Re: fuel consumption on a 78 150hp

Plan on using 15 gph at WOT. 10% of rated HP is the general rule when figuring fuel consumption.
 
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