tecumseh1

I have a low hour 1996 23.5 ' Rinker Captiva Open Bow with a 5.7 4-bbl 250 hp mercruiser.

The boat tachs about 4900 top end at about 51 MPH fully trimmed.

I am looking for an inexpensive way to increas performance and top end without sacrificing the hole shot. The boat has a 17 pitch SS prop on it.

Thanks

mopower

We all are . A friend has a 209 Captiva with your same set up and wound up putting in a worked over 408" SBC with Vortech heads and Gil Offshore exhaust. Now turns a 23" Mirage 5000 rpm and 70ish mph. Cost about $5000

ursus

This depends what you call a performance increase and what you call inexpensive.

A 17 pitch prop turning 5000 rpm with 9% slip will run 49 mph. So to go any faster you will have to get a new prop thats $500 to start, a 19" will run 55mph, 21" will run 60,mph 23" will run 66mph at 5000 rpm with the same slip. So 1st decide how fast you want to go next select the prop that will do that and next build up the motor to be able to turn the chosen prop at 5000 rpm.

You will need about 300hp to turn the 19", 365 hp to turn the 21" and 440 hp to turn the 23"( give or take 20 hp this is just a ruff guess).

Getting to 55mph, 300 hp, 19" prop, might be doable with an intake manifold/carb/cam/exhaust change, so 2500-$3000 beyond that will need new heads , new bottom end ( more cubes) etc

None of these combo's will have as good a hole shot as you have now as the low end torque will be similar on the higher Hp engines to what you have now and the 17" prop will take off better than the higher pitched ones.

Probably the most inexpensive way to gain a couple mph would be to have the prop labbed

tecumseh1

Not certain what it means to have the prop labbed