need more power

[RidgeRunner]

Actually I stand corrected, none of the 300 Mercs have a chrome bore. The 300X doesn't have paint on the block. Just the alodine type finish like the 2.5L 260 and 280 Mercury racing motors which are nicasil (coated bores like chrome). Coated bores are tough as nails and require rebuilding more often. They also spin the he// out of them (7200 to 10,000 rpm). The 3.0L ProMAx like the one advertised did not have 300 hp at the prop. It was something like 280hp. The 300x has the 300 ponies at the prop and is made to turn 6800 RPM with the rev limiter at 7100. My 250 rev limiter is at 5800 rpm and prob has around 230-235hp at the prop but because of the extra displacement over the 2.4L 200 hp Merc(like 175 hp at the prop) I saw a gain of 14 mph when stepping up. The 3.0L 225 and 250 will take some abuse as the bottom end is pretty hearty and they can be hopped up with some electronic mods, tighter heads and the like. But you give up durability IMO. Hot rods cost $$$. Then if it breaks you have to throw more $$$ at it. Fun? Oh yeah. Practical? Well that is in the eye of the beholder.

[RidgeRunner]

Shrek, RE:pitfalls of raising the motor up on a jack plate. If the jack plate is electrically adjustable from the console I don't see any issue. Install a water pressure gauge so you know what you have and try it out. Raise the jack plate too high and the water pressure will drop off. Raise it too high and it may ventilate the prop getting on plane or in turns. What motor is your 225? If you are turning it to redline or close you can't gain much by putting a bigger prop on it.
Props are somewhat of a trial and error. Ferm sent me to Ken @ prop Gods who is a wealth of knowledge on props.(Ferm Spare School and others on here too for that matter)

[THEFERMANATOR]

As for a low water pick-up, they can actually cost you speed. I know I lost speed on my flats boat with one, but I needed it for teh shallow running I did. The low water pick-up puts more material in the water in front of teh prop which increases drag. High speed boats need them though to force teh water in as teh side pick-ups lose efficiency at a certain point. Somewhere around 60-65 is when you need to consider one is what I was told.

[Shrek]

Its a 1998 3 liter carburated salt water series. I'm not sure what the red line is, but I would assume that at 5600 RPM, I've got to be pretty close. It is an electro-hydraulic unit so I can adjust it on the fly and I do have a water pressure gauge on the boat, but I wonder about it's efficacy.

As to the prop, it does not appear that I could turn a much larger diameter wheel, but was wondering about upping the pitch a bit. Do the chingered edges of the blades contribute significantly to slip?

I guess all will be answered when I install the jack plate and put the old girl in the lake.

[Shrek]

Originally Posted by THEFERMANATOR

As for a low water pick-up, they can actually cost you speed. I know I lost speed on my flats boat with one, but I needed it for teh shallow running I did. The low water pick-up puts more material in the water in front of teh prop which increases drag. High speed boats need them though to force teh water in as teh side pick-ups lose efficiency at a certain point. Somewhere around 60-65 is when you need to consider one is what I was told.

Good to know, and thanks. We do a lot of marsh fishing here in New Orleans. What kind of loss of speed did you experience with your flats boat? I was really wanting the low water pick up for the marsh. My concerns of starving the motor for water were secondary.