2009 175 sport 3.0 to 4.3

[Gentlemaleficent]

Hi all,

I’m about to inherit the project boat mentioned above. The engine does not work and it is believed to have a cracked block.

if I were to replace the engine with a 4.3, would it be a direct replacement instead of the 3.0? It doesn’t seem as if it was ever an option on the 175.

Thanks so much.

 

[Bill Curtis]

1st check what max engine HP is allowed for the boat. A 4.3 would be a lot for a 17 footer.
Yes it is possible, but going from an inline 4 to a v6 is a big jump. So is it a GOOD jump?
It will also add a lot of weight to the back and may be too much.

You didn't state make of drive system. Mercruiser w/ Alpha 1 gen 2 outdrive?

A lot needs to change, since it is 3.0 four banger, vs: a 4.3 V6. Motor mounts and mounting locations entirely different and your stringers may not accommodate. Need to check that 1st. Will certainly need new exhaust pipe on inside of the transom plate, as you would go from a single to a dual inlet.

Gearing on the outdrive will be different. Sometime ratio change can be negated by prop size / pitch change, but I bet the leap from 3.0 to 4.3 will need new gears ratio in drive unit and prop size / pitch change to handle the new HP and torque.

 

[ZZ13]

I owned that exact boat, same year. If it were me I’d put the 3.0 with Alpha 1, Gen II in just like factory. Had plenty of power to get 6 adults on plane no issue.

 

[Maggieiscrazy]

Many years ago I special ordered a 17’ Larson with a 220 hp 4.3. It only weighed 2200lbs. That thing was a rocket. With a 21” prop and just the Gf and me it would do real close to 70mph on the speedo. I had a lot of fun with that boat.

 

[Arminius]

You could try nitrous for enhanced power for short duration. This would be an interesting experiment. "Oh Boy Oberto" ran its V-12 Merlin at War Emergency Power the full hydro race with multiple tanks of the stuff.

 

[GypsmJim]

A 3 liter with an optimized Mercury SS prop will blow the doors off a 4.3 with a standard prop. I say that because my son and I had almost identical boats and he couldn't keep up with my little 4-banger.

The 3.0 is often the most aligned engine, when in fact there were more of them made and happily run than all the others combined.

 

[Maggieiscrazy]

A 3 liter with an optimized Mercury SS prop will blow the doors off a 4.3 with a standard prop. I say that because my son and I had almost identical boats and he couldn't keep up with my little 4-banger.

The 3.0 is often the most aligned engine, when in fact there were more of them made and happily run than all the others combined.

C’mon,man! 135hp vs 220hp? I don’t think so. When I had my 4.3 I raced a lot of people and no one could touch me. A lot of other boats were quicker out of the hole but when I got up on plane it was “good bye” I’m sure a lot more 3.0 have been sold then 4.3’s because they’re cheaper. People like cheap.

 

[Lazy Daze]

C’mon,man! 135hp vs 220hp? I don’t think so. When I had my 4.3 I raced a lot of people and no one could touch me. A lot of other boats were quicker out of the hole but when I got up on plane it was “good bye” I’m sure a lot more 3.0 have been sold then 4.3’s because they’re cheaper. People like cheap.

The 3.0L's are a fantastic engine. They've been around for decades and have proven themselves to be extremely robust and reliable. "Cheap" is not a word I would associate with them, though.

However, in an apples to apples comparison (same boat model), a 4.3 with an Al prop will still easily outperform a 3.0L with a SS prop. If the comparison is between different boats then that's not a fair comparison as there can be vast differences in hull design/efficiency - even if they look similar to the eye.

Truth is, a SS prop on a 3.0L doesn't offer much benefit because it just doesn't have the torque to spin up the much heavier prop quick enough to take advantage of the SS benefits. I've tested numerous props (gathering GPS and time data) with a 3.0L in a Sea Ray 180 (and other boats over the years) and found that an Al prop is still the better choice, especially when money is factored in.

 

[BillK2632]

My 185 with the 4.3 was a little rocket. The 4.3 was a solid motor, no issues in over 800hrs. No first hand experience, but have always heard the 3.0 was rock solid also.

 

[Lazy Daze]

I forgot to answer the actual question

Like others mentioned, swapping from a 3.0 to a 4.3 is doable... but it's a lot of work and expense. I would first verify the engine is actually bad. If so, put another 3.0 in. The expense of popping a 4.3 in is probably going to be more than buying a decent used boat that already has a 4.3. Plus, the "new" value of your modded boat with a V6 isn't going to be nearly enough to recoup your costs and time.

 

[GypsmJim]

C’mon,man! 135hp vs 220hp? I don’t think so. When I had my 4.3 I raced a lot of people and no one could touch me. A lot of other boats were quicker out of the hole but when I got up on plane it was “good bye” I’m sure a lot more 3.0 have been sold then 4.3’s because they’re cheaper. People like cheap.

The comparison I referred to was a 140 vs. a 190. The V6 had the prop on it that came from the factory, and based on specs it was about 150 pounds heavier. The I4 had a custom pitched double cupped SS Michigan that provided WOT rpm right at the max spec.

The boat with the 3.0 was a factory order. Actually, I could have one almost like it off the showroom floor with the 4.3, and it would have had a lower price. I bought the 3.0 because of it's rock solid history.

After switching to 4-stroke outboards a few years ago, you couldn't give me an I/O any more. Nevertheless, if I HAD to have one I wouldn't hesitate to go with another 3.0, depending on the size of the boat of course.

We had the 3.0 for 35 years, so that must provide some testimony to what we thought about it.

 

[mrsrobinson]

I had the 3.0 in my 17 foot Maxum and it did very well.

Let him put the 4.3 with nitrous in it, we will see him here soon:

 

[Pirate Lady]

Go big or stay on the porch…