About how many gallons per hour will my V-6 use ?

[Albacore Fever]

I would like to know about how much fuel I can expect to use in my OMC V-6 4.3 L engine, running a 4 barrel carb, the boat is a Wellcraft Coastal 218 Cuddy 21 ft. I think its about 3000 lbs. the main reason I'm asking this is because I like to do allot of offshore fishing and I'm worried about range, right now its got a blown head gasket and I am thinking about dropping a Vovo diesel into it instead of fixing it. I've never really been able to check the amount used because it never ran right since I've owned the boat but so far it looks to be a real gas hog. Thanks Don

 

[Howard Sterndrive]

Re: About how many gallons per hour will my V-6 use ?

I'm stealing this chart from 45Auto. It seems pretty accurate for most hulls of similar size and power to those tested. I prefer to look at mpg and speed, rather than gph. Your engine is likely capable of burning as much as 16gph or as little as 1 or 2gph, but you can take any point on the graph below and work it backwards to gph.

 

[JSMoore]

Re: About how many gallons per hour will my V-6 use ?

I run a 3800 lb, 21 ft Mark Twain, V-Sonic cuddy, with an OMC Cobra 4.3 2bbl. And, Howard Sterndrive's chart seems to be pretty consistent with my experience. Figuring MPG, using fuel consumption and my GPS trip log, I average about 3.8 MPG. I've also figured GPH, too. I topped the tank off, then ran the boat for roughly 2 hours at a comfortable 3500 RPM, and 25 to 28 kts. When I topped the tank off at the end of the run, I used 14.3 gallons - So...... roughly 7 GPH and 3.5 MPG.

Now, you mentioned your 4.3 being a gas hog. If you ain't running right, perhaps it is. But, compared to other gasoline fueled I/O packages, and for sure, outboards, the 4.3 ain't bad. The chart above illustrates that nicely.

Hope this helps some!

 

[BoatDrinksQ5]

Re: About how many gallons per hour will my V-6 use ?

thanks for the graph! nice to see some actual data instead of opinions/experiences.

 

[Albacore Fever]

Re: About how many gallons per hour will my V-6 use ?

Thanks for all the good information, before I blew my head gasket I took these readings from my fuel censor, at idle 1100 rpms = 1.9 GPH at 20 mph 3100 rpms = 11. gph at 27 mph 3700 rpms 12.3 I was thinking that was terrible but maybe that's par for the coarse ? the above results may be related to the blown head gasket, when I say that I"m thinking I may have had a leak in the gasket before it blew, I was never able to get any more than 3700 rpms under load on the water and I'm not over propped. thanks for all your help. Don

 

[fletcher123]

Re: About how many gallons per hour will my V-6 use ?

I just purchased a boat with 5.0. I did not realize how crappy gas mileage these things get. I have a 25 g tank so if I pull the kids around on tubes for awhile looks to me I have to refuel in 3-4 hrs. I thought I could go the day hopefully. At least the kids will have fun though.

 

[Scott Danforth]

Re: About how many gallons per hour will my V-6 use ?

tubing and water sports are gallons per mile, and not miles per gallon that you get while cruising at a steady speed.