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Twin 318s 1977 Silverton 31b FUEL BURN

bfiesta

Member
1977 Silverton 31' Sedan w

1977 Silverton 31' Sedan with twin Chrysler 318s. Any ideas on what gallons per hour fuel burn I am likely to experience? Original carbs. In good shape. Running a little rich. 220 gallon tank. I'll be fully loaded with fuel and beer... oh and the wife (reminder to self: don't forget the wife). Getting ready for our first big trip in the new/old boat.
 
"Depends on how much you push

"Depends on how much you push those gas eaters (throttles) forward. My 360s burn about 8 GPH each at 2,400 rpms and 10 GPH each at 3,000.

The trick to not getting taken over by Exxon is to find the "sweet spot" where the gas mileage is optimum, yet you're still getting somewhere. Each boat is different, and only by use of a Flo Scan or Navman fuel meter setup can you really find out.

Jeff

PS: Don't forget the wife!"
 
"Jeff, Thanks for the info. I

"Jeff, Thanks for the info. I have an 1988 Luhrs Allura with Chrysler 360's and was wondering how much fuel they were burning. Any idea if there are factory specs out there on how much the engine burns at various rpm's? This way, I could use by GPS to calculate speed/burn/rpm curves."
 
"Guys,

I have a 1980 34 sil


"Guys,

I have a 1980 34 silverton convertible running 360's. Jeff's numbers are just about right on for me too.

Dean"
 
"i've got 32' with twi

"i've got 32' with twin 360's. i would be interested in hearing about the vessel specs. weight, speed, for this type of burn from Jeff and Dean
thanks"
 
"1980 34 Silverton Convertible

"1980 34 Silverton Convertible
Hull 34 feet
Beam 12.6
weight 14000+ full fuel and water
gear ratio 2.05
prop size 18 by 21
HP each 275hp

Bottom condition: several layers of bottom paint.
Full enclosed flybridge

Burn ranges roughly

2000 rpm 8-10 knots 5-6 gph each

2800 rpm 13-15 knots 10-12 gph each

3200 rpm 16-18 knots 15-16 gph each

I run 2800 rpm's for cruise. 3200 rpm's is my get home in a hurry cruise. Anything above that rpm is not realistic. Secondaries seem to open at 3000 rpm's for me. Then the gas burn really take off.

I hope this helps. But keep in mind that every boat is different. I use ranges because my speed is dependent on tide and wind. Fuel ranges because I have two engines and they never read the same. But this is my numbers that I use to gauge my trips on.


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silverton
 
Dean what engines and carb do

Dean what engines and carb do you have trying to gauge mine as well mine are 270hp-360s w/new 1409 carbs going on a run thanks........
 
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