Yet another 3.0 vs. 4.3 question or two

[Quid]

Re: Yet another 3.0 vs. 4.3 question or two

Ahhh, not so fast on the fuel comparisons there. I have found that just as many seem to try and justify there larger engine purchase by claiming it gets about the same gph as the 4 banger.
I wish I could post the manual I have, but I can say its on the Four Winns website under past specs for my boat (98 Horizon QX) It lists speed, gph and rpms for each motor in the same boat..
At 3500 rpms for both, the 3.0 is 32 mph and 7 gph. The 4.3 is 35 mph and 10 gph. Huge difference for a measly 3 mph .
Lets take it a bit further; 4000 rpms for both. 3.0 is 37 mph and 10 gph, 4.3 is 42 mph and 14 gph. Another huge difference for a minimal gain
One of the big differences in the two motors is the 4.3 can run close to 5k while the 3.0 is limited to 42-46k rpms. So WOT on the 3.0 (4500) is 40 mph at 12 gph, while the 4.3 is 50 mph at 18 gph..
To sum it up....50 % more fuel to go 20% faster....what a sucky trade off...

http://assets3.fourwinnsmarketing.com/past_product/specs//1998/02 Horizon QX (p2-5).pdf

 

[ralphy670]

Re: Yet another 3.0 vs. 4.3 question or two

I am no expert by any means on this topic. The post above has some very good info. The difference in fuel consumption is better in a 3.0L for cruising speeds. I am not saying that a 3.0 cant pull skiers but it will have a tougher time with a heavier skier. I can say if I had a 4 cyl that I would need to change props if I wanted to ski or wakeboard. That to me is a huge inconvenience. I would hate to have a good cruising prop on while out with friends to acheive better fuel economy only to decide that the water is great and the crew wants to ski. (Where's my other prop again.....oh ya, at the dock 10 miles away. This is just my opinion though. No offence to anyone at all.
I would just decide what the boat will mainly be used for now and in the future.

 

[Quid]

Re: Yet another 3.0 vs. 4.3 question or two

ralphy.... actually its not nearly as bad as you would think wakeboarding behind a 4 banger. If my brother in law (260 lbs) can get up on a wakeboard with my mother in law (300lbs+?) along with 4 other people in the boat (5 total) then I can assure you most anyone else can as well..with the factory pitch prop. Would the 4.3 have strained a bit less? I'm sure..but...
With $4 gal gas and rising I think the minimal gains to be had in the 4.3 are not worth recommending nearly as much as they used to be..

 

[ondarvr]

Re: Yet another 3.0 vs. 4.3 question or two

Quid

I was looking at the numbers you posted on fuel usage. RPM's don't mean much, look at the MPH and GPH, not a big difference, 4.3=10 GPH at 35 MPH, 3.0=10 GPH at 37 MPH. It kind of jumps up the same for each speed, only the 4.3 allows you to go much faster if needed. I don't point this out to agrue, just to make it a more accurate comparison.

I don't do the family watersports thing anymore, but when I did, more HP (to a point) was always better. I know people that have taken a big loss on a boat by not getting the right motor up front, thinking the smaller engine would be "adequate" and it sort of was just adequate. The second time around they normally went for more HP.

 

[Quid]

Re: Yet another 3.0 vs. 4.3 question or two

ondarvr..yeah you're right, there is that sweet spot right dead in the middle where a 4.3 can be almost as efficient as a 3.0.....
Maybe thats where all the hoopla about a 4.3 being fuel efficient comes from (Just funnin...)

 

[jaxnjil]

Re: Yet another 3.0 vs. 4.3 question or two

my neighbor bought a boat with a 4 cyl volo 3 or 4 years ago and his son was around 8. the first summer he had it his son knee boarded and it was just him his son and his wife. this boat was the best thing since sliced bread.
now his son is water skiing, his brother moved out from back east and his dad him his brother and son all want to go fishing.all i heard last summer was man i wish i had bought more boat.
unless you have a crystal ball and know for sure what your furure is going to bring, go big. the larger will do any thing the small one will but not the other way+any 6 is going to run a lot smoother than a 4

 

[642mx]

Re: Yet another 3.0 vs. 4.3 question or two

I can't believe there is so much bickering about fuel mileage.......lol. Its a BOAT! No boat gets good fuel mileage, who cares if a 4.3 burns more than a 3.0?...... If your worried about if a boat gets 5 mpg or 6, then you don't need a boat....simple as that.

 

[45Auto]

Re: Yet another 3.0 vs. 4.3 question or two

Excellent data Quid!

Hard to find real comparisons of the same boat with different motors. The FourWinns site you referenced had data on the same boat with 90, 115, and 150 HP outboards as well as the 3.0 135 HP I/O and 4.3 190 HP I/O.

My point was that the 4.3 does not use 2X the fuel.

I put them into a graph so it’s easier to talk about.

If you want to talk about Gallons/Hour (GPH) it makes more sense to compare equal flow rates.

At 3500 rpms for both, the 3.0 is 32 mph and 7 gph. The 4.3 is 35 mph and 10 gph. Huge difference for a measly 3 mph

Ok, let’s start with 32 MPH. The 3.0 is burning about 7 GPH, the 4.3 is burning about 8 GPH. Obviously going to use more gas with the 4.3 - but not twice as much, which seems to be a popular claim.

On the other hand, if you slow the 4.3 to 28 MPH you burn 7 GPH just like the 3.0 at 32 MPH. But the 4.3 has lots more potential (50% more power available – 190HP vs 135HP) if you need it. Huge difference in available power for a measly 4 MPH gain in cruise speed at that flow rate (just as a reference point, an 8.1L, 425HP in a 22’ boat burns 7.8 GPH at 28 MPH. Huge difference in potential power and a much larger boat if you're willing to cough up that extra gallon per hour. Figuring 100 hours/year, the bigger boat with the 8.1 would cost you $400/year extra at $4 gallon gas).

3.0 is 37 mph and 10 gph, 4.3 is 42 mph and 14 gph. Another huge difference for a minimal gain

Pretty obvious there, that 5 MPH cost you 4 GPH with the 4.3.

So let’s slow the 4.3 down till it’s burning 10 GPH just like the 3.0. Now it’s only doing about 34 MPH. So the 50% in power potential that the 3.0 gives away to the 4.3 is worth 3 MPH at a 10 GPH burn rate. Another minimal gain in cruise speed for a 50% sacrifice in power.

My experience has been that if you’re just cruising around nobody notices or cares whether you’re going 28 or 32 MPH. Obviously if you were going somewhere 32 miles away it would take you about 8 minutes longer to get there at 28 MPH. But if the point is to cruise anyway the time really doesn’t matter. If you’re willing to give up a couple of MPH cruise speed the 4.3 will burn the same amount of fuel as the 3.0.

If you’re determined to run the same speeds, then at 32 MPH the 3.0 is 7 GPH and the 4.3 is about 8.1 GPH. At 37 MPH the 3.0 is 10 GPH and the 4.3 is about 11 GPH.

So to run side by side the 4.3 will cost you about 10% more in fuel. If you run a full tank of gas through your 3.0 boat (24 gallon tank according to the website) it will take the 4.3 an extra 2.5 gallons per tank to run beside you. If you’re willing to cruise 3 or 4 MPH slower in the 4.3 they will use the same amount of fuel. Be interesting to see how much difference a full load of people or skiing or tubing would make. And the 4.3 will always have that 50% power advantage and 10 MPH higher top speed if you need or want it.

I also found it interesting how much more fuel the 115 and 150 HP outboards used.

And as 642MX says, if $10 a tank (2.5 gallons) makes that much difference to you, you're probably better off without either boat in the first place .............

 

[Quid]

Re: Yet another 3.0 vs. 4.3 question or two

45Auto...you rock, dude...love the graphs. It all comes down to you're constantly paying to have that extra poterntial, even if you never use it. To some paying a minimum of 10% more constantly would never be worth it to be able to go faster than 40ish.
Boy that 150Hp OB line is scary, aint it? Hate to have to feed a 2 stroke with todays prices!

 

[erlindbl]

Re: Yet another 3.0 vs. 4.3 question or two

Go for the 4.3. First count how many times your going to have that boat out on the lake. Then figure in what that minor difference in gas milage is going to mean to the total cost of your day on the lake. You still have to pull the boat out there and back and that's gonna cost you the same plus lake fee, beer (big expense here) and food. The difference you spend in gas for those two boats isn't going to mean much.

I gaurentee however, you will be sorry if you go for the smaller engine. Your kids are going to grow. Your going to have adults in that boat, the kids are gonna wanna ski together. You will never get two reasonably sized people out on slalom skis behind a 3.0 boat without some serious dragging.

Do yourself a big favor. Don the wet suit, fill up the two boats and have them pull you out with each. You won't need any other advice on this page.

I hade a 17 foot runabout with a 5.0 for 24 years from when my kids were babies to adults. That boat served my purposes and had plenty of power. I could pull three adults on slaloms with it. Just bought a Glastron GT 180 that comes in tomorrow. I got the 150 E-tec with it. Had I gone with the I/O I would have undoubtedly gotten the 4.3. For the times your going to use it, you will want the power.

 

[ovrrdrive]

Re: Yet another 3.0 vs. 4.3 question or two

Getting away from the technical discussion and going back to more practical, I just sold my Searay BR176 with the Mercruiser 3.0l engine in it about a month ago. We loved the boat, but I would definitely say it was underpowered at least to me and how I wanted to use the boat.

I go about 250lbs, and the boat would pull me great on tubes, kneeboards, and on 2 water skis but on a slalom ski, no way. I quit swallowing water at about 3 gallons and finally let go. Even though i rarely ever slalom ski, that always bothered me that when I did I had to get up on 2 and kick one. As a matter of fact, we came back to one of our skis once to find someone loading it into their boat...

While I always wanted more power, I have to admit that there were only a few times other than skiing that I actually needed it. I used to cruise around 28-30mph, and always wanted that to be higher to 40 for riding down the river.

The main reason I sold it though is that I wanted to fish and was always afraid to fish out of it because it was too nice of a boat. I wanted a little bigger, with a little more power, and live wells.

 

[kywildcat]

Re: Yet another 3.0 vs. 4.3 question or two

I wonder what his final decision will be.

 

[durdy]

Re: Yet another 3.0 vs. 4.3 question or two

I wonder what his final decision will be.

4.3.

Excellent information in these replies. Thank you all very much especially 45Auto and your Excel plots. You're speaking my language. Much of my time is spent in answering performance questions about a certain line of telecommunications equipment under development. It's difficult to quote a single representative metric covering all operating conditions. Curves are the only way to go and even then you need to produce a lot of them to get the full story out.

It's pretty clear there's no one clear answer to this question. I am going for the 4.3 for a few reasons:
- the boat can handle it - it's the GT's max horsepower rating
- I should be able to load up the boat with people and still tow
- I like the sound of the 4.3 better and it looks more impressive (I am a guy)
- When I want to go really really fast I can goose'er and get there in a hurry
- It will remove any would'a should'a doubt in the coming years, months...
- The initial price difference won't break me. I'm already getting deepish with a new boat
- The fuel economy difference won't break me
- If/when a 3.0 fuel injected motor comes out in the next year or so I won't feel that bad for buying now; the carbed 4.3 will still have more power, the carbed 3.0 would have a bit less
- ultimately and honestly it's what I really want

I'm also quite convinced the 3.0 would also be fine. But I have the option of not compromising so that's what I'm going to do.

 

[45Auto]

Re: Yet another 3.0 vs. 4.3 question or two

Congratulations on your new boat Durdy!

Glad the graphs helped you out. I also spend much of my time on my job trying to compare the performance of difference types of equipment. As you say, data curves are the only practical way to compare parameters over a wide range of inputs.

I think you made the right decision with the 4.3, hope your family enjoys your boat as much as my family enjoys ours! My kids were 11, 13 and 15 when we got our first boat 7 years ago and we've been out almost every nice weekend since then.

 

[QC]

Re: Yet another 3.0 vs. 4.3 question or two

Awesome decision!! The best fuel economy advice I ever got (25 years ago) was: "you're only talking about $5 a day . . . " Even with today's gas prices, for many boaters, it is still the same discussion.

 

[Tubingluvr]

Re: Yet another 3.0 vs. 4.3 question or two

I have had many bowriders with many different combo's.
Never been able to afford a new one though.....all my boats have been mid to late 1980's.
What I have found is if you can find a 4.3 with a 2 barrel carb it is actually better on gas than a 4 cyl.

 

[Quid]

Re: Yet another 3.0 vs. 4.3 question or two

Tubingluvr....what sort of carbed 4.3 have you had to do that? Maybe the pre-vortec 4.3s since they barely made enough power to justify having 6 cylinders, but definitely I wouldnt think the later models carbed would even come as close as the graph, which represents a throttle bodied 4.3.
Fuel injection has always provided a significant economy advantage over a comparable carbed engine.
If only they would put FI on the 3.0....

 

[Dakota47]

Re: Yet another 3.0 vs. 4.3 question or two

Dont be fooled, the 4.3 V-6 is MUCH better than the 3.0 i have had both.. & i still have the 18ft Rinker with a 4.3 V-6. going out on it today..

 

[PhatboyC]

Re: Yet another 3.0 vs. 4.3 question or two

I also found it interesting how much more fuel the 115 and 150 HP outboards used.

Same here. They are both 2 cycle? Would be nice if they test the new 4 cycles to compare.