Looking for HELP for more speed ,power & RPM

[SouthernWolf]

<br />I have a 1987-195XLC Chapparal fiberglass hull with a OMC-4.3 & OMC-Cobra outdrive..With a 2 barrel Carb .The prop I'm running is a aluminium 15-1/2-15. At full throttle I'm tacking 4800 to 5000 rpm,,but only running about 35 to 38 MPH. or at least thats what the speedometer is showing, Could it be something wrong with the speedometer? I'm thinking my engine size and Carb size i should be running about 160 hp or little more,But should'nt my speed be better?? What should I do or what needs to be done,or am i in the wrong and my boat is running right <br /> THANKS

 

[blifsey]

Re: Looking for HELP for more speed ,power & RPM

Do you have access to handheld GPS (friend, etc.)? I would check speed with GPS first and go from there. Maybe someone here can tell you if that is proper RPM range for that motor.<br /><br />BL...

 

[Bondo]

Re: Looking for HELP for more speed ,power & RPM

it looks like you need at least a 17" prop to lower you rpms.. the 4.3 is happiest at 44/ 4500rpm WOT.... your over reving it now...you maybe able to spin a 19" for a little better top speed,But your lowend power will drop off...