Question about Prop pitch and size.
#13
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From what I have read, Mirage props are mostly made for big block boats. This one is 15 1/2" big. Most 19 or 21p props are around 14". So maybe I just need to go with a smaller diameter prop like a 19p 14" Laser. Does this sound right?
#14
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CALL BBLADES they have a prop swap you give them your info they send you a prop for testing its a little extra say 25 bucks I would start with a laser 21 and if you pick up speed but are a little low on rpms you can have it labbed to get them back if the 21 is right at 4800 I would go to a 23 and lab it that should get you back to 4800 and you might pick up 5mph. a friend of mine is putting in a 350 325hp he had a 220hp merc before its a 17ft runabout we are hoping to turn a 24 3 blade turbo prop I have which will have it running in the 60plus range . if not he will buy a 21. art
#17
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Hey Iggy, he is not even close to what that small block should be running RPM wise, you really think he can pull a 21?
A 21" isn't all that big. My 1988 F-206 LS Formula has the original 260hp 350 MAG and it came from the factory with a 21" Mirage (which I still have) on a Alpha drive. Top end is 58 mph @ 4800.
How much should I trim her up. I stop trim just before i get a little roster tail.
Last edited by Iggy; 07-23-2007 at 11:29 AM.
#18
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My trim indicator is broke too. Its just kinda frustrating because I see all these people with stock 5.7 260hp hitting 55-60 and here I am with a Vortec 350, comp cam and a 750 carb and I can't get anything decent. My boat is only 20.6' so its not like I am pushing a 24' with a 350.
#20
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Ok, I tried a 19pitch cleaver prop. yesterday and got the rpms at 5200 but still only got 53mph. Do you think I should go to a 21 or 23? I was thinking a 21p laser would get the rpm down and maybe a few more mPH.