496 MAG vs. 350 MAG engines in choice of boats - help me decide

[LippCJ7]

Re: 496 MAG vs. 350 MAG engines in choice of boats - help me decide

Short answer . . . No. All low speed handling characteristics go to the B3. I don't belive there is one exception.

And you would be wrong, the one exception is if I am at the controls, my wife makes me look like an idiot at low speed, launching/retrieving etc. shes a pro. At speed I am THE MAN though!!

 

[Hank496]

Re: 496 MAG vs. 350 MAG engines in choice of boats - help me decide

We have a different brand, but similar boat - 28' hull, single 496 with BIII 2.0:1 gear ratio. So a couple of comments;

1. The 496 is closed cooling
2. The 496 is Smartcraft ready
3. @ 3400 we can maintain about 23-25 knots at 16 gph approaching 4000 rpm speed increases to about 30-31 knots fuel burn rate is 32 gph
4. Upgrading this engine to a BIII will be a huge improvement.
5. Since the 496 is a re-power, make sure it was done right. The 496/8.1 engine package has a problem at low / idle rpm in that it develops very little pressure in the exhaust system. Early installs suffered problems with the engines ingesting water through the exhaust system. The solution was to increase the riser stack height well above the waterline. You might want to double check to make sure this engine was correctly installed in the boat.
6. The raw water pump on there 496 when coupled with the BIII frequently can not generate enough head to self prime. The only solution that works all the time is to add a through hull water pick up. Amazingly enough, Merc sells a modification kit to block off the water line through the transom.

 

[tswiczko]

Re: 496 MAG vs. 350 MAG engines in choice of boats - help me decide

The 350 MAG is a great motor but I think 8K would be a bit much for that motor let alone the loaded weight of 10K

I have an older 24' with a 350 Magnum in a 4K empty weight and guessing around 5k loaded and we can hit 50mph wot so I would think in that tug you would be lucky to get a 25mph cruising speed I would definitely go with the large displacement

 

[JoLin]

Re: 496 MAG vs. 350 MAG engines in choice of boats - help me decide

Definitely the big block.

I went boat shopping last fall. Trialed a '95 Carver 280 Express with 7.4L Merc. That's a light boat for its size. Carver claims 7000 lbs with fuel and water. The single engine was okay. I wouldn't have had an issue with it, but it wasn't a powerhouse.

The Four Winns I bought specs out at 7400 lbs. dry, so figure about 8500-9000 loaded up. Twin injected V-6's. Seat of the pants impression was that it has better response and is quicker to plane than the Carver was. According to Four Winns' archives (they're excellent, btw, if you can use them for comparative purposes), performance and fuel consumption numbers for my boat vs. the same model with a single 7.4, are virtually identical.

FW didn't even sell my boat with a single 5.7, nor did Carver. I think you'll be okay with the single 8.1, but I wouldn't consider a single small block in that size boat. I think you'd be very disappointed.

My .02

 

[QC]

Re: 496 MAG vs. 350 MAG engines in choice of boats - help me decide

I too like the 496 combination in this discussion, but I want to clarify something that I think is important. The 7.4Ls of old that JoLin references were rated as 300 or 310 hp at the propshaft (shp). It could be argued that the newer MPI 350 Mags rated 300 shp should be as strong. If you consider they weigh slightly less, then maybe even makes up for the measly 10 shp difference. Oh, and I know you guys get sick of my rant on this as well, but I don't think any peak torque difference is significant, especially with a B3 drive. The fact is, unless you are at 100% throttle you are not utilizing peak torque at any RPM. Just a couple of things to ponder.

Unless we are talking 454 Mags (385 shp), or 496s (375 and 425 shp) or 502s, then I don't think the old rules regarding big blocks vs. small blocks are as cut and dried anymore. This is especially true when you get into 6.2s and going to be even more true when we finally see the awesome 6.0s. I think I'd like to add to the old adage of there is no replacement for displacement and tack on, but horsepower is still horsepower. And if anyone here hasn't seen my ramblings about the misunderstanding of peak torque, and it's relative value, you have been warned

 

[Bondo]

Re: 496 MAG vs. 350 MAG engines in choice of boats - help me decide

I think I'd like to add to the old adage of there is no replacement for displacement and tack on, but horsepower is still horsepower. And if anyone here hasn't seen my ramblings about the misunderstanding of peak torque, and it's relative value, you have been warned

Ayuh,... You guys seem to be covering the Motor/ Drives issues quite well,...

I'm just gonna jump in here to make 1 point,...

With a boat that's gettin' on to 2 Decades old,....

1st thing I'd be doin' is crawlin' around the bilges with a flashlight, 'n inspection tools,...
Lookin' for Rotten stringers, 'n transoms,...
Maybe even Soaked foam,... Donno on a 28'er...

Even a Bayliner...

 

[tswiczko]

Re: 496 MAG vs. 350 MAG engines in choice of boats - help me decide

Ayuh,... You guys seem to be covering the Motor/ Drives issues quite well,...

I'm just gonna jump in here to make 1 point,...

With a boat that's gettin' on to 2 Decades old,....

1st thing I'd be doin' is crawlin' around the bilges with a flashlight, 'n inspection tools,...
Lookin' for Rotten stringers, 'n transoms,...
Maybe even Soaked foam,... Donno on a 28'er...

Even a Bayliner...

Bond-o is right on that (as usual)

Thanks for reminding us a boat is more than a prop motor and drive . I hadn't thought about the rest of the boat since I felt the question was primarily about which engine is better suited for the craft.