Does Anyone Know This Merc 5.7 Horsepower???

[Alex_AGB]

Re: Does Anyone Know This Merc 5.7 Horsepower???

The vortec heads will not take more than .470 lift in stock form.

Given it is an efi, I don't think the merc is reprogramable, before you start to get crazy with mods.

That?s not a big deal. If I was going to do a cam swap I'd have to change springs so I?ll pull the heads and machine the guides, change the valve seals, and get some +.050" keepers. Then she'd be good for .500" plus lift.
EFI doesn't need to be reprogrammable, Just need to upgrade to bigger injectors and maybe a fuel pump.

 

[Don S]

Re: Does Anyone Know This Merc 5.7 Horsepower???

Here we go again. Time to get out the popcorn and watch the automotive guy go wrong in the marine world. Didn't we just go through this a few weeks ago..........

 

[Alex_AGB]

Re: Does Anyone Know This Merc 5.7 Horsepower???

I found these cam specs for an older 2 piece rear main seal 260hp merc...

202 intake duration

214 exhaust duration

395 intake lift

404 exhaust lift

112 lobe separation

110 intake centers

 

[Alex_AGB]

Re: Does Anyone Know This Merc 5.7 Horsepower???

Here we go again. Time to get out the popcorn and watch the automotive guy go wrong in the marine world. Didn't we just go through this a few weeks ago..........

haha, I'm here to learn.
I'm not looking to build a race engine here. I'd just like to have a full roller valve train. There are lots of marine cams both roller and flat tapped.

 

[Don S]

Re: Does Anyone Know This Merc 5.7 Horsepower???

The engine has a roller cam, is reliable, and is TBI, controlled by a MARINE ECM that is not user programable.

 

[TilliamWe]

Re: Does Anyone Know This Merc 5.7 Horsepower???

The engine has a roller cam, is reliable, and is TBI, controlled by a MARINE ECM that is not user programable.

And they run REALLY strong! Leave it alone, please. You won't make much "improvements" and you'll have something more tempermental and less reliable, possibly, when you get done.

 

[Philster]

Re: Does Anyone Know This Merc 5.7 Horsepower???

Spend a few hundred bucks and get a labbed, real quality SS prop from a big prop maker manufactured in the past 1-3 years. That's it. That's like getting the tranny/tires/rear to really hook up and bite, giving you that last .5 you were looking for. And, the boat drives better w/ better mileage.

Nothing you are going to do to that engine will ever really matter on the water for happy boating.

Car guys forget the boat needs to have a cam that is happy with it's ONE gear from start to top speed. Also, cruising in a boat means churning along at 4000 RPMs sometimes. What cam specs does a car guy have that will help? None. If the cam isn't helping the engine pull in this gear, you downshift, right? Wrong.

Boat engine builders who build performance engines drop them into boats that are going to run offshore at a certain high-RPM range, and they give up all the other things boaters want and need: drive-ability. They use carbs, too.

ECM and injection are good for boating. You want to do something like run at 4400 RPMs for an hour straight, then cam away, lose the fuel injection AND ECM and start hanging around guys who can't sleep at night going 63MPH, so they spend 20k to hit 70MPH and then forget what boating is.

 

[Alex_AGB]

Re: Does Anyone Know This Merc 5.7 Horsepower???

start hanging around guys who can't sleep at night going 63MPH, so they spend 20k to hit 70MPH and then forget what boating is.

Good point. I think I'll hold off on the engine mods for now. That?s just how I get when I buy something new, I always want to mod it in some way and get my hands dirty...
That being said what is a good prop to get and what pitch would I need for my horsepower range?

 

[Philster]

Re: Does Anyone Know This Merc 5.7 Horsepower???

Nobody wants 70 MPH more than me -- well, except for the guy spending 20 grand to get there! So, I really really feel your pain to want more performance, no matter what it is. I learned that I can get about 20 HP for about 5 grand, make a bunch of noise and get nothing in terms of performance, because 20 HP isn't enough to get me to a bigger prop, and a bigger prop is what is needed for more speed. 50 HP would cost me upwards of 7500. Then I get 2-3 MPH.

Okay, head over to the prop forum, and post the engine and HP, weight of your boat, type of boat, the am't of gear and people you tend to have on it.

You'll need to tell us about the current prop numbers: number of blades, year, pitch, size/diamter, material (alum or Stainless) the RPM at wide-open throttle and anything else that can help us, like time to get on plane. I think the prop forum gives more info on what is needed.

Do you want power out of the hole (4-blade or 5-blade) or top end (3-blade)?

Essentially, if you know exactly what the boat does on the water, you can probably get a perfectly matched prop that gets you right to redline under most conditions.

If the prop is newer, has aggressive cupping and raking, and if you spend a little more and get it labbed (the final, final tweaks to match your boat/experience), you are as close to getting 100% from the engine as ever. Modern props benefit from years of design/tweaking and the latest in computer aided design.

 

[Don S]

Re: Does Anyone Know This Merc 5.7 Horsepower???

That being said what is a good prop to get and what pitch would I need for my horsepower range?

Might want to post that question over itn the prop forum. Until you get the boat, get all your stuff on board, then find out what prop it now has, the speed and max WOT rpms are, there is no way to say what prop.

 

[John_S]

Re: Does Anyone Know This Merc 5.7 Horsepower???

Good point. I think I'll hold off on the engine mods for now. That?s just how I get when I buy something new, I always want to mod it in some way and get my hands dirty...
That being said what is a good prop to get and what pitch would I need for my horsepower range?

Along with props, other non-engine mods to look at, include tabs, either manual or smart tabs. They help with planning, reduce V-bow wander, and can even provide a little wot speed.

 

[Alex_AGB]

Re: Does Anyone Know This Merc 5.7 Horsepower???

Thanks for the help guys! Bare with me, I know I?m a newbie but I catch on pretty fast.:redface: