Any 253 Convincer with 454mag experts wanta led a helping hand

[over board]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by SED:
here it goes...97...253 Convincer...454 mag...bravo 1..with a nose cone...c-mate says to run a 23 mirage plus and spin the motor at 4900...rev limiter is set at 5080 from the factory...ok...i put on a 23 mirage plus and am in the rev limiter and have barely even started to trim..so i go to a 25 mirage plus and great ...out of the rev limiter but am only turning 4100 rpms..not good....so i put on my bravo 1 24/4blade and am now turning 4500 rpms..and am only getting 56.4 mph on GPS...Something is not right here...According to c-mate this boat should run 65-68 mph...what are everones suggestions on what to do now to get RPM's and MPH up to where they should be....Again..454 mag(110 hrs)...bravo 1 with imco nose cone and all stock...Please help <HR></BLOCKQUOTE>

I have a 96 253 convincer w/a 454 mag efi. When it was stock it would run 64-65 mph with a 24 hydomotive Q-4 @ 4800 rpms. I ran 67.4 one time on gps. I tried several props, mirage (3 blades) a turbo etc. I never found a prop that was any faster than the Q-4, plus it made the boat handle better. I should have run a 23 Q-4 for better alaround performance

 

[mkhammer]

I agree 24 pitch - blade should be the way to go

 

[mkhammer]

I wanted to add a 454 mag efi puts out 385 hp. a 454 mag carb has less rated hp with less torque. this is a good reason why he can't turn a 24p prop like the mag efi.

 

[over board]

correct.
A 454 mag efi= 385hp
A 454 mag carb= 350hp

So I would estimate 2 mph less in a 253. even at that it seems he down on spd and/or power.