3,0 vs. 4,3 - fuel consumption?

[SeaRayViking]

Have just sold a 20ft SeaRay, which i owned with a friend of mine. The boat featured a merc 4,3lx (205Hp). Now we're about to buy a new boat and we're arguing a bit about engine size.
I love the power (and sound of course) of the V6 and would like a 4,3 again. My friend wants the same size boat (18-20ft), but wants to settle with a 3.0.

My point is that i think that we'll loose some of the smootheness of the sailing - due to loss of power, as the 3.0 must work much harder all the time than the 4,3.

And how about fuel consumption? I'm no expert, but my point is: will the difference be that markable? A 4,3 that's working effortlessly or a 3,0 working its *** off?

note: We've seen a regal with a 4,3 volvo GL - that enginge should be quite economic, right?

Well - can some please help two boating beginngers (we've only sailed for two years...)

 

[billbayliner]

Re: 3,0 vs. 4,3 - fuel consumption?

I have some thoughts on this.....

I have a 19.5 foot bowrider with a 3.0 LX Alpha 1 gen 2 and it has PLENTY of power and I can get it to 42 MPH. Gas mileage is excellent.

Reliability of the engine along with maintainance cost is excellent......

I do EVERYTHING with this boat and would not change from the 3.0...

With this said if you are going to get a 20 footer, with cuddy adding more weight then maybe the upgrade to a 4.3 would be best.

Remember, with the upgrade come increase costs anually with preventative maintainance cost.

Bill

 

[tashasdaddy]

Re: 3,0 vs. 4,3 - fuel consumption?

personally i would not own a boat any size with a 3.0. they have to work too hard to achieve what they do. 4.3 is minimum, in my book. especially in a 20.

 

[scoutabout]

Re: 3,0 vs. 4,3 - fuel consumption?

I'll weigh in with kudos for the 3.0 but it's got to be in a boat that makes sense. Our SeaRay 170 (actually 16.5 feet long) was a lively performer, if not a rocket. Sipped gas, rock solid reliability and pulled 200 pound skiers with ease.

I would have expected the picture to change considerably with that motor in a 19 footer, so it's interesting to get billbayliner's perspective. I would still consider a 20 footer would way too big for that motor but a sea trial with a load representing how you would use the boat would confirm it.

 

[mthieme]

Re: 3,0 vs. 4,3 - fuel consumption?

My SRV190 has a 170 hp 4.3. I burn an average of 3 gph which is very economical. I've resisted the temptation to stick a SBC in her for this very reason. I for one don't expect gas to stay under $2.00 forever either.
While I can't speak for the economy of the 3.0, I can tell you that it will be underpowered if you plan on loading much more than yourself and a six-pack.

 

[Mischief Managed]

Re: 3,0 vs. 4,3 - fuel consumption?

There will be almost no difference in fuel economy for a given speed. The lower weight of the 3.0 will help give a little bit better economy, but not much, a couple tenths of an MPG at best.

 

[tmh]

Re: 3,0 vs. 4,3 - fuel consumption?

I have some thoughts on this.....

I have a 19.5 foot bowrider with a 3.0 LX Alpha 1 gen 2 and it has PLENTY of power and I can get it to 42 MPH. Gas mileage is excellent.

Bill

While I am sure Bill offered this advice honestly, I think for the OP we need some clarification ...... For one person, PLENTY of power can mean getting he and his wife a quite slow cruise around a small lake. others definition of Plenty of power is haulling arse with 8 people and lots of suppies aboard!

A top end of 42 mph (and i assume that's NOT with a max load on a 19.5' boat) puts you at nearly the slowest newer runabout on the lake. low end will be at the low end also - has to be because thisis the lowest sterndrive power option. Do YOU have to be able to go over 42 mph????? Well, I have to, but you may be totally different. I also want the boat to pull for watersports with 7-8 people and gear aboard - who wants to be left at the dock so the boat can get out of the hole?

Anyways, i always wonder if we are talking the same language on performance. there is a very good reason most experienced boat owners would never buy a 19'+ boat with a 3.0L engine in it. there's also a good reason that when you see those underpowered boats on the used market they are being given away - relatively speaking.

A very light, shallow boat like some Stingrays, maybe (but not for me) .... but anything heavier and/or deaper ...... no way in a 20' boat.

 

[mylesm260]

Re: 3,0 vs. 4,3 - fuel consumption?

Someone posted a graph once, showing a compairson between fuel burned and speed, and it had the 4.3 vs the 3.0

the 3.0 was about 5-10% less fuel at any given speed.

But, some things to consider:
To my knowledge, very few 3.0L's are Fuel injected, most are carbed.
Most 4.3's are fuel injected now adays.

EFI will give you much much better milage in the long run. After a year or two, the carb on the 3.0 will drift slowly out of adjustment, and the EFI'ed 4.3 will give you better fuel economy.

3.0's have much less torque than the 4.3.. this means that in order to get the same hole-shot, your running less prop/gears.
That means that in order to do the same speed, the 4.3 will be turning much lower rpms than the 3.0. RPMS = wear... so if both boats were doing 35 MPH, the 3.0 would be wearing much much faster than the 4.3.


I personally woudn't put a 3.0 in anything bigger than a 16' boat. Your just working the motor too hard to get anything done.

 

[sickwilly]

Re: 3,0 vs. 4,3 - fuel consumption?

That new 3.0 fuel injected engine may just make some of us 4.3's believers.

 

[bhammer]

Re: 3,0 vs. 4,3 - fuel consumption?

I have a buddy who looks at the boat and finds out what the manufacture "base" package was at delivery and then will go one up on the engine for a given boat. Now, we all know this will not work in all cases but goes to the fact that most manfg. underpower their boats to reduce the initial "sticker" shock.

I ahve a 1900 Starcraft open bow and it is about 19'6" and 8'6". Ii is a heavy boat due to it's size and my family of 6 and gear can way it down. It has the merc 4.3L injected and that engine is barley enough to make it. Now, with just me and a little fuel, it will really move.

I guess the point is, if you are going to buy a boat, try to test to see how it works for you and your condition. Gas is not going to be a player between the two, unless it's a couple bucks a weekend. In that case, you probably shouldn't own a boat to begin with.

There are plenty of 19 footers on the lake with 3.0 in them that will out run my 4.3 injected. I am much heavier and more boat in the water on plane....

 

[SeaRayViking]

Re: 3,0 vs. 4,3 - fuel consumption?

This is interesting reading - Thanks a lot for sharing your views!

If anyone knows where the before mentioned chart (3.0 vs 4,3) is located, a link would be great.

Cheears, thanks

SRV

 

[642mx]

Re: 3,0 vs. 4,3 - fuel consumption?

A 3.0 may be good for some, but I think if you owned a V6 powered boat and dropped to a 4 banger.... your going to be pretty disappointed. The power is a night and day difference and if your worried about fuel economy then you might need to find a different hobby. Not trying to be mean, but no boat gets decent fuel economy.... so you might as well have plenty of power.

 

[jevery]

Re: 3,0 vs. 4,3 - fuel consumption?

Stingray 195 LS W/3.0 (21 Gal Tank) / Stingray 195 LX W/4.3 (35 Gal Tank)
(Length, Beam, Dry Weight are same)

http://www.boattest.com/boats/1758/test_results.aspx
http://www.boattest.com/boats/1766/test_results.aspx

 

[ksubigbuck]

Re: 3,0 vs. 4,3 - fuel consumption?

It looks like the 4.3 gets better mpg at 42 mph. Get the V6, you will regret it if you don't.

 

[Boatist]

Re: 3,0 vs. 4,3 - fuel consumption?

I have a 21 foot Aluminum Runabout, the one in the picture. I have the 3.0 I/O and love it. I think the 4.3 EFI is also a great package.

For me it more a question how fast you want to run. My 3.0 tops out at 38 but usually cruse at 25 to 30 inland and 18 to 20 offshore and the 3.0 if fine for that.

I did have 10 people on my boat one time and the 3.0 would barley plane but then I had the wrong prop on for that kind of a load. I should have had my 17 pitch instead of my 19 pitch. Problem was I never expected to take that many people and will not go more than six form now on as that what my boat is rated at. Problem was many people wanted to go to lost isle to party but no one wanted to take a second boat. My bad choice.

Not sure if your a saltwater boater or not but one big difference in the two motors is maintenance cost in salt water. When it time to replace the manifold and elbows the 4.3 will cost double.

 

[tashasdaddy]

Re: 3,0 vs. 4,3 - fuel consumption?

the graph sort of proves my thought.
at 4500 they both are getting the same fuel consumption.
you are getting higher speed, better MPG. and you still have another 1000 rpms to WOT.

 

[180shabah]

Re: 3,0 vs. 4,3 - fuel consumption?

The difference in overall fuel usage between a 3.0 and a 4.3 (on the same boat) will be less then the difference created by adding (or subtracting) one 200lb friend.

It takes X hp to push a certain hull(at a certain weight) to Y mph. It could be from a 3.0 at 4000rpm or a 4.3 at 3400rpm or a 5.7 at 2900rpm - the biggest factor will be how efficiently those engine produce that Xhp at those rpm's. With different engines your ideal cruise speed will change, but your overall fuel consumption will be virtually unchanged.