Prop diameter diffrence??? with pics
 

Hey guys, I have a question for you.
I have a 1984 Wellcraft Excalibur with a "stock" 330hp 454, and TRS drive. Only mods is Lighting headers, thru hull exhaust, and eldbroke performer intake manifold. Last year before the performance bolt-on's it would run at 5,000rpm's but after the bolt-ons for this year it runs at 5,500rpm's. It has a Quicksilver Mirage 21P SS prop (part number 48 13702 A41 21P)
So for the heck of it I picked up a Mercury Marine Vengeance 23P SS prop (part number 48 16320 23P).
The diameter of the 2 prop's is a big diffrence. The quicksilver is much larger and now iam wondering even if the pitch is 2 sizes up will the Vengeance really help me since the dia is smaller on the vengeance?
Thanks for your input! Sorry for the way I measured the prop's but it gives you an idea of the size diffrence!..
Erik

Vengeance on the left..........Mirage on the right
http://i126.photobucket.com/albums/p...6467328838.jpg

http://i126.photobucket.com/albums/p...6467343314.jpg

http://i126.photobucket.com/albums/p...6467360477.jpg

Well today I said screw it and water tested both my orginal mirage prop and the vengance prop with a hand held GPS.
The Mirage 21P prop was turning 5,500rpm's and max speed was 53mph.
The Vengance 23P prop (smaller dia) was turing 5,600rpm's and max speed was 48mph.
So not only did the Vengance prop give me more rpm's I lost MPH also..Iam going to get a 23P mirage prop this time.. :drink:

Erik

What's your goal on RPM, 5000? You said you run a "stock" 454/330. You have the bolt-ons, but still have the cast internals! WOT for that motor is 42-4600. I run the same motor, 454/330 completely stock but spin it to 4800 at WOT. I wouldn't run anymore than that with the cast internals, but it's your motor not mine. I would try a 25p Mirage, should get you to about 4700 or so or try a 24p Bravo 1 4 blade.

Yeah still stock cast internals, but i was going to run it up to 5K..I guess thats a bad idea? I have a 23P mirage prop coming next week so I'll just test that out and if still no good I guess I will have to reprop it.