Prop Help 454 MAG?
 

I have an 89 Century Ultra I with a 454 MAG carb. and Bravo outdrive. Its stock except stainless marine headers and risers. I'm currently running a 23P 3 blade mirage prop, peak rpm is 5200 and I can get about 64 mph by the speedo in perfect water. Could I get a little more top speed with a different prop or is this ideal. The valve cover says 4800-5000 peak rpm I believe. Thanks for the help!

Check your speed with a GPS first...I doubt your doing an actual 64 mph...then go from there.

I would try a 25p Mirage plus prop, if thats an accurate top end RPM thats to high.

Sounds like you have the correct prop. Maybe get it lab finished or a little more cup. You can't go by the "Dream O Meter", GPS is much more accurate.

I think you have the right prop. It certainly doesn't hurt anything to be running a couple extra hundred RPM on flat water trimmed out. As you know when you have to tuck the drive in due to rougher water those extra R's come in handy. You can always try another prop however I doubt very much you'll gain anything and lose a lot of bottom end and mid range.

I am not real familiar with all the particulars of your boat however your speedo seems to be pretty accurate assuming your bravo is a 1.5. Regardless of what it says your set up seems just fine.

John

5200rpms is fine to spin a 454 mag. You could pick up some speed with labbing your current prop and adding pitch or getting a labbed 25. You're very close, so only try subtle changes.

Thanks to all. I'll keep my eyes open for a deal on a 25P to try.

I'm not sure i agree with that being the right prop for the boat. If you are going 64 MPH, that equals 16% slip, which can certainly be improved.

Quote:
You can't go by the "Dream O Meter",

Now that made me laugh,cuz it's so true, even though as I sit here with a broke motor with two bad heads.:drink:

Going from a Mirage to a Mirage plus will lower the rpm's by about 150 - 200. If you try to go from a std mirage 23 to a mirage plus 25 you will drop to about 4600 and the boat will be very sluggish in the acceleration dept and probably loose some top end. Look for a Plus 23 or a non plus 25 to try or possibly a Bravo 1 24"
Good Luck