After the longest winter in my life, splashdown date was tuesday for some prop testing. As some of you know, I bought a 223 last December and got to go out twice before winterization. The boat saw a top speed of 68.7@5200 with a Hydromotive 4-blade and about 50 gallons of gas. The motor is a Merc 454/425 with a little bigger Ultradyne cam and Gil exhaust. I'm thinking about 460 to 470 HP. The Mercury website suggested a Mirage Plus 25P so I got one to try. Here is the results. Any help would be welcomed

All speeds are GPS- about 3.5 less than the speedo reads

25 Mirage Plus

3000 RPM = 40.7
3500 =49.8
4000 =58.6
4400 WOT =64.2

23 P Hydromotive 4 blade

3000 RPM =35.1
3500 =43.7
4000 =52.4
4500 =61.3
5000 WOT =64.7




Tests were done with a full tank of gas for both props (79 Gallons) and just myself onboard (200 lbs.)

Did the heat (97) and 30 gallons of fuel rob me of 4 MPH and 200 RPM's?

Yes.

We had a 223 with the old 454/Alpha, so we did not do anything to the engine. It ran about 58-60. I ran best with a clever style prop.

mike

I have a cleaver prop that I am going to try out this weekend. I've been running a 24" Turboprop. I have heard the cleaver will help with the tendency of my boat to heel sharply to port. It is a 20SC with a 330hp/5.7. The cleaver is a 23", but it has a larger diameter.

The 25P Mirage was surely too much prop.If I turned that @4400, what should I turn a 23P?

I was turning 4500 with the 24 turbo, that was without trimming. I couldn't trim it at all, or it would start porposing like crazy.

The Merc site also recommended the 25 Mirage Plus for my boat, which I am quite sure would be too much.

97 degrees will rob you of about 8% HP

The 25P Mirage was surely too much prop.If I turned that @4400, what should I turn a 23P?

Does anyone know what the rule of thumb is on that. I seem to remember that it was 300 RPM's for 1" of pitch. Is that correct?
If thats it than I'm thinking a 23 Mirage would take me to 5000.
How many additional RPM's could I get from labbing? I want to get 5200


Thanks, Craig

on a good lab job, you should pick up 300 rpm!! notice i said good!!!!

Who do you recommend for labbing?