Best prop for a 1993 Formula 271
04-14-2010, 01:03 PM
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Best prop for a 1993 Formula 271
I have a single 502 efi motor in the boat and took it out for its first ride last sunday. Noticed it would only get up to about 55mph and it seemed like it was underpitched. What kind of prop would you use for this boat? The tach read 5000 rpms with the hammer down and the drive trimmed up. Im thinking about a 24 pitch 4 plade or possibly a 25 pitch?? let me know the best prop to use. Im not majorly concerned with getting out of the hole id rather have the top end speed. Would like to see it do a little better than 60mph.
Thanks for your help.
Thanks for your help.
04-14-2010, 03:50 PM
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I don't think there is any way your going to spin a 25-26 pitch 4 blade prop at the proper rpms. Your boat is very similar to the formula 242. with 415 hp the 242 will do about 61-63. Your boat is 1 foot longer, 3" wider and close to 1000 lbs heavier. 58 would be my guess as to a realistic top speed as it is. Your going to need to modify your engine if you want more speed. To me your prop seems correct. That engine is supposed to be propped around 48-5100 rpms which is right where you are.
04-14-2010, 07:02 PM
#5
I don't think there is any way your going to spin a 25-26 pitch 4 blade prop at the proper rpms. Your boat is very similar to the formula 242. with 415 hp the 242 will do about 61-63. Your boat is 1 foot longer, 3" wider and close to 1000 lbs heavier. 58 would be my guess as to a realistic top speed as it is. Your going to need to modify your engine if you want more speed. To me your prop seems correct. That engine is supposed to be propped around 48-5100 rpms which is right where you are.
it is what it is ......mo power ...
04-15-2010, 03:23 PM
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I'm not. I'm building a 550 hp bbc and I'm hoping to see 70 mph. From the research I've done on this it seems the 330 is good for about 53, the 365 does about 57 and the 502 boats from what I've read are in the 61-63 range. The HP 500 motor = 69. My 242 SS did 47 with a 350 mag (270 hp). The twin engine boats did about 66 but an extra engine and drive is a lot of extra weight and drag. I'm selling my SS and redoing an LS I picked up over the winter.
04-16-2010, 12:00 AM
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Im thinking of borrowing my friends 24 pitch 4 blade. Theres no reason why my boat couldnt spin that prop. He has a 2004 30ft checkmate convincor with a single 496 mag and consitently hits speeds of 65mph with that prop. So im thinking thats gotta be the right setup for me... any advice?
