Engine Rebuild Questions -- Need Advice
 

My Merc 454 IV went a few weeks back. Cause was a bad oil pump. I have pulled the engine and delivered it to the machine shop to get rebuilt. This morning I was giving my quote. I have trouble deciding between the two as the second is outside of my budget by about $1200. Essentially, I would have to wait another month or so before I could raise the funds to get the engine from the shop.

Choice 1.
460, .30 over
Stock gm assembly
Stock cam, top end.
new gaskets
$3600

Choice 2
496/ .60 over - Scat 9000
SRP forged dome pistons
Comp Pro roller cam & lifters.
new gaskets
port matching
stock heads
$4800.


Im not sure its worth spending the extra ~ 1200 and losing a month of the season. My brother, who is a marine mechanic states that its best to go bigger as I would gain a few extra mph. Is a few mph worth an extra 1200?. How much HP/torque am i looking at if i choose choice 2? For reference, the boat is a 241 liberator. This may seem like a no brainer, but I'm very new to this hobby.

#2 the speed bug will get you. Do the 496 if you decide to buy another boat you will have the engine already done

am i realistically looking at a big increase in speed though? From what I read, every 100hp equates to 5mph

Take that quote a triple it when all said and done. Thats not including doing anything to the outdrive.

In November of 2015, I too, went down this road with a EFI 454 . First thought was to go with a 496 Stroker.out of my 454. "Read a thread called Building a Sleeper", if you would like to know how it turns out......Good Luck!...................

I have a bravo 3 drive, hydraulic steering already. Im not sure on the engine though. It has the 7/16 rods, rect heads, and forged crank of the efi motor. It was carborated though. Its a gen iv block.

Im not looking to build a sleeper, but I'm looking to have a rebuild of the current block. It just so happens that with the block has to be bored anyway.

Do what you want to do. If you do what you don't want to do because of others and it doesn't work out fore you or to your standards, we are all azzholes.


Like they say in Shark tank when they don't want to deal "And with that. I'm out."

no, more like 1-2

rule #1; speed costs, how fast can you afford to go?
rule #2; there is always someone who can afford to go faster.

if you are just using the boat to enjoy being on the water I would go with the first option unless the boat really struggled before. boats are a black hole for money so as papasmurf said you can likely triple the estimate once all the "extras" are added in.

You've already basically answered the question for yourself: 1) you want to be on the water using the boat more than the appeal of engine repairs/upgrades. 2) you've got a fairly tight budget (not a bad thing or something to be ashamed of, just a reality of the project to keep in clear focus).

With that in mind, being practical and pragmatic is the better approach for your needs. If you do a stock-ish rebuild, you're not likely to pull it back out this winter to do upgrades on a fresh engine and tossing new parts into the scrap pile. Just keep in mind that you're already into June and getting a rebuild back this time of year won't be a quick turnaround. Then factor in extra time for any parts that aren't on hand, plus anything that comes up during the R&R process might cause additional delays. Then factor in some Murphy's Law time and you're well into July most likely. Then heaven forbid you get a bad part or an improper assembly situation or you get a little excited and don't break the rings in fully and she starts puking oil and back out it all comes. Point being, time is whatever it ends up taking and you might as well just plan on not having the boat for a while and if it all works out sooner, bonus. At this point, some extra time to fund a different approach won't likely derail your summer use much more anyway- if you chose to go that route.

Not to overstate the obvious, the engine's just a big air pump, and getting more air in/out is what going to increase the power produced. To what degree and at what price, there's some debate to be had, but in general terms, more air = more $$$. What can't always be quantified or summed up easily is the usable power gains, running efficiency, and value of money invested that you'll realize in the project. Sure spending $4k for a stock-ish rebuild might net you arbitrarily say 300 HP and spending another $2k might get you an additional 70 HP. Stock she runs 65 and the extra $2k gets you to 67mph. Big deal. But maybe out of the hole it jumps on plane much quicker and then it cruises better at 750 RPM less and burns a bit less fuel to get there and mid-range punch with that cam upgrade really snaps you from 25mph-50mph night and day quicker. Suddenly that extra $2k seems like the best investment you've made and was well worth a couple extra weeks out of the water.

No idea how many hours were on your engine or how tired she really was, but a quality stock-ish refresh is going to feel great to begin with and depending on how the sum of any additional parts upgrades work together in your configuration, she might feel like an entirely new animal altogether too. Not because you're suddenly running down Skaters with twins, but because the usable experience in terms of your specific boat are that much better. Don't think there is a right or wrong approach, but I'd personally lean towards investing a few extra $$$ now for longer term enjoyment with less to worry about or wonder "what if".....

(Lastly, maybe put a general location in your profile, helps people know the area you boat in, weather you deal with for how long/short your season is, and often if someone is available they'd be happy to lend a hand if they're in your neck of the pond)

He never stated what kind of boat.

Why people do that, I don't know.