anyway to add power to a 3.0 merc?

[Nashport_native]

I have done all the basic tune up stuff (plugs,wires,points) currently my 18ft boat does 34mph at 4500rpm with a full load of fuel and my wife and son with me in the boat. I would like to get it to around 40mph if possible. does anyone make aftermarket manifolds for it? (intake, exhaust)

I am just looking for a little more out of this boat for this season, untill I can fbuy the v8 boat i want.

any help would be great, thanks

 

[fat fanny]

Re: anyway to add power to a 3.0 merc?

40 to 45 is all your gonna get out of her if your lucky with the right prop clean hull and smooth water. I suggest you loaf around the prop forum for awhile with all your powertrain info handy (motor&outdrive size and make)the guys there might be able to help wiyh a little top end but don't exspect much more mph than above listed.

 

[Matt89GT]

Re: anyway to add power to a 3.0 merc?

I have heard it takes 10 horsepower to gain 1MPH and if your running 34 MPH at 4500 good luck squeezing another 60 horse out of it to achieve 40 MPH, I dont think you will be able to, but ole boy, (charger boy is his name I believe) on here is gonna supercharge his 3 liter you need to hook up with him.

 

[bomar76]

Re: anyway to add power to a 3.0 merc?

I am just looking for a little more out of this boat for this season, untill I can fbuy the v8 boat i want.

Be very happy with the engine you own untill you make the move to more HP.
The 3 liter 4 banger is the most rugged and dependable engine ever put in a boat.
They normally outlive whatever hulls they are installed in, some here do have great luck in murdering them but it takes a lot of neglect and effort to do so.

You will never get the HP gains you need to achieve the speed goals you have form that engine.
Take care of it and look forward to your move up some day.

 

[dazk14]

Re: anyway to add power to a 3.0 merc?

What prop are you running. That generally gives the most bang for the buck.

As suggested post on the prop forum.

Fill out Hwsiii form and I'm sure he'll find a few mph(unless you've already found a performance prop).

 

[JaseBosto]

Re: anyway to add power to a 3.0 merc?

uh, my 2000 Stingray 3.0 hits 47 on the water(GPS). 19 pitch 3 bladed SS prop.
You need to trim up to get that tho.
At that speed I am around 5000 rpms

 

[Bondo]

Re: anyway to add power to a 3.0 merc?

At that speed I am around 5000 rpms

currently my 18ft boat does 34mph at 4500rpm

Ayuh,... 4800rpms is the # to look for,....
Sounds like 1 of ya needs a Bigger prop,+ 1 of ya needs a Smaller prop...

 

['94Glastron]

Re: anyway to add power to a 3.0 merc?

My Glastron 175 with the 3.0LX and a 14.25 X 21 trimmed high and at w.o.t will do 48-50mph at 5,00rpm. Gonna try a 14.25 X 23 to get the rpm's down where they need to be and MAYBE get a few more mph at the same time.

 

[Tommywalton]

Re: anyway to add power to a 3.0 merc?

I had issue with mine. 95% of the time my boat is towing wakeboarders. My 21x15 kept my Rpm too low at that speed(22mph) I went down to a 19x15. Raised my rpms by 500. Pulls like a tug boat. But I have a 300hp 5.7 in a 19.5' bayliner Capri. Top speed 35mph. Prop diameter and pitch mean way more in your case than hp. Believe me though 100 hp per liter can be had for about 7k. Forced induction and radical head and intake porting. Bigger blow through carb, 10 psi boost blah blah. Just buy a v8