Prop for 1988 baja 235 Force

mats · 09-24-2005, 12:42 PM

Hi
I am trying to find a good prop for my 1988 Baja 235 Force.
It has a stock 1998 502 MPI with Gil Exhaust. Should give some 440 hp on the propshaft. The current prop is a 23 inch Mirage Plus. The engine revs 4700 rpm fully trimmed out. The top speed is about 60 mph on GPS. Seems low to me for this size boat.The boat weighs 3600 lbs +400 lbs gas and driver. Are there any better props for speed and/or handling?

Whiteknuckle · 09-24-2005, 10:08 PM

You seem to be experiencing a lot of slip, about 19% by the calculator. Your horsepower estimate also seem a little on the optimistic side for the figures you are stating. I am no expert, but I would want to spin that engine up a couple hundred RPM more, and I think if you explain all the details to one of the good prop shops here on OSO they could lead you in the right direction. For top end, I think you will most likely stay with the Mirage. I don't know how your boat will respond to a 4-blade, that is why you should get the prop people involved.

AIR TIME · 09-25-2005, 11:47 AM

try a rev 4 23p merc or a reg 23 p mirage not the plus I had a 502 390hp at the prop turned a reg 25p mirage at 4800rpm that was in a 24sport 88 4000lbs dry 67mph

RBeyer · 09-25-2005, 04:22 PM

21 Mirage Plus

throttleup · 09-26-2005, 01:46 PM

The 502 needs to run at 5000 RPM at WOT. What drives and gear ratio do you have?

Julie

mats · 09-27-2005, 04:51 AM

It´s a Bravo One Drive with 1.5:1 gear ratio

mats

throttleup · 09-27-2005, 09:59 AM

I have calculated your slip at 12% which is great for a 3B propeller. I would make one suggestion though the 502 needs to run at 5000 RPM at WOT as this is were the peak HP is produced on your motor and this is were peak top end is found. So you may want to owrk your propeller for the additional RPm or possibly try a 21P Mirage Plus.

Julie

mats · 09-27-2005, 04:39 PM

Thanks
I´ll try a 21 inch prop.

Mats