We are looking for a second boat. Something that is smaller and will pull like a bear. Something good for towing water skiers. I keep finding boats in great shape with Mercruiser 4.3 stern drives. I want one with a 5.7 liter V8. Does anyone have experience with a 4.3 V6? I know I am spoiled rotten. Our 22 footer has a 454 big block Chevy. It pulls fast and hard. Thanks in advance.

Like all boats, several factors determine performance. You have already mentioned displacement/HP. Some others that affect pulling power--perception of expected performance like pulling during deep water starts done by skiers and wake boarders, top speed, cruising speed, most efficient, etc.

For example
1. A smaller boat with the right engine, prop will do a great service for pulling up skiers.. A lower pitched prop will get skiers up, even with a"medium sized engine. For example, I ski Flat Head Lake in Montana now and then behind a 16 foot aluminum fishing boat with a 90 hp engine outboard. Too tall a prop may give you higher speed, but if 35 mph is good enough, then a "low gear" prop will do an excelent job.
2. Number of people aboard, and their placement in the boat. Too much weight will slow down a boat considerable. On our 17" Eliminator with OMC 3.8 litre engine worked great with a 17" prop with three people on board it was a great performer as long as they were properly spaced around the boat--except at 5000 foot elevation., when it took forever to get on plane. A reasonable planing speed like 3.5 to 5 seconds will usually do what you want it to do.. Skier skills also determine what you need. I learned as a high schooler behind a 35 hp Johnson on a small boat. Wasn't easy, but I was able to ski.
3. On and on. I think you know all this, but for other readers, it might be helpful..
4. Fuel injection will generally give you better performance, but carbs have done the job for many years.

If you are interested in a specific boat, a water test is good to experience. Some I/O engines will have a max RPM around 4800-5000. With wide-open throttle and two people in the boat, trimmed properly, look for this range..

My personal experience is that the 4.3 in a 17' to 18' boat will do the trick for you. It's a give-and-take proposition.between speed and pulling power.

Lots of great points Jack T!

Our 22 footer with a 7.4 Liter Bravo 1 does a poor job pulling up a skier when we have the 23 pitch prop on it, however with the 17 pitch prop it will pop a skier right up.

We had a 1980 Astroglass 17.6 bass boat from the time it was new until about two years ago. With it's original 115 HP Mercury outboard and two people on board it would pull up a large skier without difficulties. I don't remember what prop it had.

I guess the main point is that I don't want an underpowered boat.

My sister had a 17 foot bow rider with the 4 cylinder Mercruiser set up. It was a terrible ski boat. Her kids could ride behind it, but they could come up behind a canoe. Boat was a real piece of junk!

My cousin had a 19' Searay with a 4.3 in it, and it pulled great! We got 4 skiers up at one time. It was hard, but we did it! 2 of us were 200+ lbs at the time, too.

Our Regal has 2 of 'em... 28' long, 10' beam, and they get the beast on plane nearly immediately.

Caveats:

It has Regal's Fastrac hull, which some folks had me believing only works ON plane- may be, but this boat planes as fast as our Chap did! Was quite a surprise--

Not sure which Volvo DP props are on it, but cruise speed, if memory serves, isl like 28mph at 3400 rpm, so they're definitely not steep props and probably a good reason for the fast plane. I believe I topped it out at 36 one day too. Only had it out twice, and didn't even use it last year, and not yet so far this year so it's all from faded memory

I have a video of us getting on plane in the thing, think I can find it??

We had a 1995 Rinker 209 with a 4.3lx. Was a nice combination. Had lots of fun & good power.

Lots of 4.3's around . . . no real issues with the engine. A 5.0 in a 20 footer would be ideal, but as mentioned 18-20 feet w/ a 4.3 is still very do-able.

I couldn't begin to guess the actual %, but a portion of the extra power gained with a V8 is spent simply pushing its extra weight around...

The actual % is probably not much. Some folks think they will save gas with a smaller engine, but the best fuel economy is achieved by having an engine that is properly sized for the boat. If you run a smaller engine, you can actually use more fuel, because you will have to run it closer to the WOT throttle range than if you had a bigger engine.

"--but the best fuel economy is achieved by having an engine that is properly sized for the boat..."

Definitely truth to that!
I came across this video below just yesterday, cruising Flaming Gorge in the Chap, taken in August 2015, which was 2 months after pulling the sinking SkipperLiner out. This was probably the last ride we ever took in the Chap, since the rest of that summer was spent fixing the Skip and the Party Cruiser. We sold the Chap the following February after buying the Regal, which we've taken out all of twice for a whole hour each time. I'm Jonesin' for boatin' BAD!

What I make note of in the vid is our RPM to speed ratio which was very good for gas mileage- and it was doing it with DP props I'd bent all to hell on some golf ball-sized rocks, and bent back myself! Boat weighed in the 7's and the big 8.1 had no problem pushing it around. I still miss the $#!| out of that boat, lotta good memories

https://youtu.be/rADTOtkMmwE