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57 and 350 mag difference

K

Kev1n

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What is the difference between

What is the difference between a merc 5.7 and a 350 mag? If my 19 foot Vindicator runs 64 mph with a 250 hp 5.7 how much more performance would I get out of a 350 mag? Can it be converted?
 
"Assume you mean the 350 MAG M

"Assume you mean the 350 MAG MPI engine.
The 350 and 5.7 are of course the same basic engine.
You could likely convert yours, but it would be expensive, and not worth the hassle.
YOu would get the convenience of no carb and choke to mess around with, easier starting, etc.

If you want a significant imporvement in performance you need a bigger engine to start with. A 6.2 MAG MPI would be a marginal improvement at 320 hp.

Otherwise you need a 496 or 502 big block. Since your Alpha drive is only rated for 300 hp, you would have to swap it out for a Bravo, which would be several thousand more bucks. Plus the big block weighs about 150 lbs more than the small block.

You could put a blower on your 5.7, but you still have the drive power limitation.

Sounds like you would be better off to sell the boat and buy faster one. What's wrong with 64 mph; that's moving pretty fast on water. Have you ever hit a piece of driftwood at that speed?

Rod"
 
"So your saying that I really

"So your saying that I really only have 50 hp left to gain anyway before having to step up to a bravo? 50 extra hp is probably only a few more mph anyway. I see your point about buying a faster boat; however, if I did swap the drive how much horsepower would a blower add, would it create maintenance issues and who makes one.
I never see any 5.7 modifications or performance enhancing parts in any of the power boat magazines."
 
"Kevin;
There are about a qua

"Kevin;
There are about a quarter zillion 5.7's out there, and there are all kinds of aftermarket performance parts available through the custom engine and speed shop houses.
You can swap heads, intakes, carbs, cams, rocker arms, multiple carbs, stack exhausts, and so on and so on.
You can also buy a "built" marine 350 that will make 400+ hp if you like.
Its all a function of how wild you want to get and how deep your pockets are, and what kind of gas you want to use.

If you start bolting performance goodies on your stock block (consider how many hours are on it), you will of course erode its reliability accordingly. With a blower you can get a 50% power increase, so 400+ hp is achievable. But there is the drive issue, and you could easily blow up the bottom end.

Consider that a boat's top speed will increase as the square root of the power increase. That means that if you power up to 375 hp (50% increase), your speed increase would be about 22.5 %. You would see about 78 mph. That's quite fast for a 19 ft boat; you would be the King of the lake. Meanwhile your fuel consumption would be 50% higher.

Most standard deep V hulls start to get squirrely above about 70 mph, so stability may become an issue. I am not familiar with the traits of the Vindicator.

Rod"
 
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