how much more gas will a v8 use then a 4 cyl?????

[snowman51789]

i curently have an 18' bow rider that has a 3.0lx (135) that weigh's 2200 lbs, i am looking at buying a 20 foot wellcraft eclipse that have a 350 v8 in it that weighs 3000 lbs. both are carberated. i am just woundering about how much more gas i would be using? i know there are alot of details involved. im just looking for a round about answer or if anybody is out there that mybe made the same upgrade or something. i manly just do cruising and some wakeboarding and tubing.

agian i know there ALOT of details involved, im just looking for some educated guesses.

thanks

David

 

[jigngrub]

Re: how much more gas will a v8 use then a 4 cyl?????

About double.

 

[26aftcab454]

Re: how much more gas will a v8 use then a 4 cyl?????

1981-Glastron SX-190---350 SBC-292hp -408ft/lbs tourqe--Run hard-pulling tube 3-4hrs on 12 gal gas -2 weekends on 20 gal tank.

 

[Fireman431]

Re: how much more gas will a v8 use then a 4 cyl?????

Plan on about 1/3 more. It's the HP to weight ration that will dictate, with all other elements being equal (hull design, water conditions, tuning, etc).

 

[kmarine]

Re: how much more gas will a v8 use then a 4 cyl?????

about 25 to 30% more depending on engine type and what you are using your boat for. pulling waterskiers with a smaller engine will burn more at full throtle than a larger engine at half throtle. I believe it is better to have the v8 engine if you dont beat on it. You might spend less on service because they are known to last 30 years if properly maintained.( personal expierience)

 

[rallyart]

Re: how much more gas will a v8 use then a 4 cyl?????

Not much at all. Unless you drive it like it now has a V8.
You are adding some weight which means you have to push more water but it's not a huge amount relative to the total weight of your loaded boat. If you use the extra power you use extra fuel, so a new higher top speed means you'll use more fuel when you are running at it. When you accelerate out of the hole you will come on plane quicker so you might use less fuel with a more powerful engine in that situation. When you are cruising at any given speed your hull will require a specific amount of power. The V8 or 4 are both producing that much power at that speed and because the amount of power is related directly to the fuel used you use the same fuel. (with a small adjustment for the increased weight)
The only time you really use more fuel is when you are doing things your 135 hp would not do, like top speed or accelleratation while on plane.

This is based on the supposition that the two engines have similar technologies and operating efficiencies.
The big difference is the total weight of the bigger boat and any hull design. The guess of 25% more fuel is probably good because your smaller boat weighs less than the newer one. Then ingine is not the issue.

 

[marcoalza]

Re: how much more gas will a v8 use then a 4 cyl?????

Fireman & kmarine are spot on.

Bet on about 30% more. Double the cylinders does not mean double the guzzle.
Working less hard for the same job.
With more grunt comes better efficiency per litre.

 

[H20Rat]

Re: how much more gas will a v8 use then a 4 cyl?????

my bet is more than 30%. I'd say 50% or better. Why you ask? It isn't an apples to apples comparison. You are comparing not only twice as many cylinders, but also 2 extra feet of boat and probably an extra 1000 or more pounds. If it was identical hulls, I'd say 30% would be fair.

 

[mnypitboat]

Re: how much more gas will a v8 use then a 4 cyl?????

Looks like you got your answer. Like said, if you are flogging on it all the time, you will suck some gas down. If you take your time and drive normal, and assuming both boats are in perfect running order, 30% sounds about right. Now if your 3.0 was not quite running right and your V8 is, then you may not even notice.

I just changed from a carbed 5.7 to a 5.0 fuel injected, and I swear it feels like I am using half the gas.

 

[drrpm]

Re: how much more gas will a v8 use then a 4 cyl?????

I have a 20 ft Mariah with a 5.0L MPI engine. There's usualy 6-8 people on the boat and we do a fair amount of tubing and wakeboarding with some swim breaks in between. It usually burns about 10 gallons of gas in a 4-5 hour afternoon at the lake. The engine spends most of its time running between 2,400 and 3,000 RPM.

 

[Susquehanna Squid]

Re: how much more gas will a v8 use then a 4 cyl?????

It all depends on how hard you run it........ Oh, and what Marcoalza said!

 

[jmarty10]

Re: how much more gas will a v8 use then a 4 cyl?????

I have a 20 ft Mariah with a 5.0L MPI engine. There's usualy 6-8 people on the boat and we do a fair amount of tubing and wakeboarding with some swim breaks in between. It usually burns about 10 gallons of gas in a 4-5 hour afternoon at the lake. The engine spends most of its time running between 2,400 and 3,000 RPM.

Interesting - thats about what I'm getting in my 4.3 6 cylinder that's carbed. I had six out on Sunday doing heavy tubing and I burned probably 8 gallons in 2.5-3 hours running at 3k RPM

 

[marcoalza]

Re: how much more gas will a v8 use then a 4 cyl?????

my bet is more than 30%. I'd say 50% or better. Why you ask? It isn't an apples to apples comparison. You are comparing not only twice as many cylinders, but also 2 extra feet of boat and probably an extra 1000 or more pounds. If it was identical hulls, I'd say 30% would be fair.

You're absolutely right sc, I was just answering the question comparing engines as per the subject but not taking into account the different hulls.