Mercruiser 5.7 Fuel Consumption

[Mattee]

I am looking at getting a 19ft , 1995 Larson Lxi with a 5.7 Liter Mercruiser Sternleg.
I was wondering, how many liters an hour i would go through with wakeboarding.
My current boat has a Suzuki 200hp Exante on it, and it chews through the gas

 

[dubs283]

Re: Mercruiser 5.7 Fuel Consumption

if you are that concerned about fuel consumption, don't go with a V-8

you would be just fine in a 19 ft boat with a 4.3 V-6, plenty of pulling power with better fuel economy

 

[Mattee]

Re: Mercruiser 5.7 Fuel Consumption

Thanks for that, I was thinking that would be the ideal option. The 135hp is not grunty enough. But the 190, should have the torque and economy

 

[dvandsm64]

Re: Mercruiser 5.7 Fuel Consumption

we have a 19 ft. with 5.7 liter with 2 barrell. some 4.3 liters have a 4 barrell and i bet are just as harsh on fuel as the v-8. anyhow we like bragging about having a v-8. but to each their own.

 

[45Auto]

Re: Mercruiser 5.7 Fuel Consumption

Go to Boattest.com, Boatingmag.com, Mercruiser Boat House Bulletins, etc, and look up some actual test data.

You'll find that the 3.0/4.3 will be around 5 MPG, the V8's will be around 4 MPG. In most cases boat size and weight has more influence than engine size (sorry, you'll have to convert to liters!).

A 5.7L I/O will probably give you about twice the fuel economy of your current carbed 2 stroke outboard.

From Boattest.com:

 

[nola mike]

Re: Mercruiser 5.7 Fuel Consumption

i'm curious as to the testing conditions...my 4 banger gets 3.7 mpg in "normal" driving, mostly keeping it around 3k rpms. when i'm pulling skiiers, it drops to 3.2 mpg.

 

[buzzm19]

Re: Mercruiser 5.7 Fuel Consumption

I'll pay for the gas, you pay for the repairs. Remember you are pushing water not coasting down the highway. 26' nova ll twin 260's, 1hr running good, 25gal gas and you only live once. Buz

 

[Bt Doctur]

Re: Mercruiser 5.7 Fuel Consumption

minimun cruise 5-7 gal/per hour
max rpm with a good 4 barrel 30-40Gal/per hour

 

[45Auto]

Re: Mercruiser 5.7 Fuel Consumption

i'm curious as to the testing conditions

Test conditions for the 3.0L Maxum. The others are similar:

 

[nola mike]

Re: Mercruiser 5.7 Fuel Consumption

hmm. i may do a controlled, continuous 10 mile run this weekend and see. i wonder if the difference is driving conditions, fuel injection, or my engine running rich (plugs looked ok at last check). feel like i should at least be matching an 8.1L/22'!

 

[wire2]

Re: Mercruiser 5.7 Fuel Consumption

I am looking at getting a 19ft , 1995 Larson Lxi with a 5.7 Liter Mercruiser Sternleg.
I was wondering, how many liters an hour i would go through with wakeboarding.
My current boat has a Suzuki 200hp Exante on it, and it chews through the gas

It makes a huge difference how often you stop/start. Every start will eat the same fuel as 1 km or more of cruising. I used to ski a lot, I know.

I have a 19' Glastron SX190 with a 5.7 with some free breathing (performance) mods. I get up on plane fast, then pull it back to ~2700 rpm for cruising at 30+ mph.
With 4 people plus gear on, I can go from Buckhorn, ON, to past the Kirkfield lock and back in 9 hours, without refueling. Tank is 35 US gallons (132.5 liters). The tank is low but not empty on return, so figure ~30gal.
The trip includes 5 locks each way, actual distance is 162 Km (100 miles) by boat;
http://en.wikipedia.org/wiki/Trent–Severn_Waterway

so it works out to 3.3 mpg. That's way better than what I used to burn with a Merc 650 O/B, plus it burned expensive oil also.

Keep in mind, a 4.3 has a numericaly higher gear ratio than a 5.7 so it has to run faster for a given speed.

 

[Howard Sterndrive]

Re: Mercruiser 5.7 Fuel Consumption

neat to see the 3.0 briefly dipping below the 4.3 economy around 30mph.

That 4.3 mpg line in that chart seems to reflect exactly what I have been seeing on my LMF200 fuel flow meter in my 18 footer / 3.8/4V V6.

I cruised at 32-33 mph before the meter, now I cruise at 27-28mph and you can see why on that chart

 

[6meter]

Re: Mercruiser 5.7 Fuel Consumption

When my tank is empty, I put more in. Simple.

 

[fossill]

Re: Mercruiser 5.7 Fuel Consumption

In my opinion and personal experience you dont want to run anything less than a v-8 in a 19 foot or larger boat. 4.3 might be ok lighty loaded but you you load up full passengers, gear and fuel and then start doing watersports, that boat isn't performing. My buddies 5.7L, 19 footer gets the same fuel economy than my 4.3L, 18 footer when out for the day doing watersports, his fully loaded, mine with a 80% load. I assume its because he's got a whole bunch extra power and doesn't have to put the throttle into it as much.

 

[nola mike]

Re: Mercruiser 5.7 Fuel Consumption

neat to see the 3.0 briefly dipping below the 4.3 economy around 30mph.

That 4.3 mpg line in that chart seems to reflect exactly what I have been seeing on my LMF200 fuel flow meter in my 18 footer / 3.8/4V V6.

I cruised at 32-33 mph before the meter, now I cruise at 27-28mph and you can see why on that chart

yeah, that's a fun chart. it'd be better if they compared different engines/same boat. hard to make a case for buying a 3.0L though...

 

[Mattee]

Re: Mercruiser 5.7 Fuel Consumption

Thanks Guy's for the awesome feedback. Getting double the mileage than the boat i own now. Sounds very good. Looking at the mileage charts, if the 3ltr and the 5.7ltr are fairly close at a low cruising speed. I was wondering what is the general consensus, for the right speed for wakeboarding. My speedo flickers, so i lock in the rpm. I find a couple of me mates, go too fast when towing me or others behind their boats. Does 18mph sound right.

 

[jtmarten]

Re: Mercruiser 5.7 Fuel Consumption

I doubt you'd stay on plane @ 18mph. I tow my son & his cousin (16yr olds) on a tube around 25mph, roughly 2600rpm, all day long staying on plane.
If you're not towing on plane, your fuel economy will really suck.

 

[jtmarten]

Re: Mercruiser 5.7 Fuel Consumption

I'll pay for the gas, you pay for the repairs. Remember you are pushing water not coasting down the highway. 26' nova ll twin 260's, 1hr running good, 25gal gas and you only live once. Buz

Still 2+mpg running twins, 4+mpg/engine, assuming you're running mid-50s. I think I get better avg mpg with the twins than I did with my 23' 454 jetboat. The jet was way more fun though. Still miss it.