1988 242LS Speed Help
#15
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Joined: Dec 2006
Posts: 23
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From: spokane wa
Im spinning a 26p bravo 1 4 blade at 5200 rpm . i need to gps the boat the speedo hits 60 then heads backwards . then again im running a 502 with a comp blower cam and a procharger pushing 7-7.5 lbs of boost
#16
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Joined: Dec 2006
Posts: 23
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From: spokane wa
was out this weekend got 70.9 mph at 5000 rpm half a tank of fuel four people and a cooler . might has ben able to trim out a couple more mph but the wife was getting spooked so when i saw the 70 mark i called it good .
#18
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Joined: Nov 2003
Posts: 2,296
Likes: 3
From: Lake Travis ,Texas
Was that 428hp reading from your 454 on a boat style dyno or a car one ?
Meaning did you run your boat manifolds and all accesories
to get the reading? If not then your engine real hp might be more
like 380-390hp in the actual boat which would make your mph of
62mph pretty close to what it should be and not bad at all.
Just something else to consider
Meaning did you run your boat manifolds and all accesories
to get the reading? If not then your engine real hp might be more
like 380-390hp in the actual boat which would make your mph of
62mph pretty close to what it should be and not bad at all.
Just something else to consider
Well I just tested my boat out on the CT river this weekend and I showed 62mph at 5,000 RPM with a 21 pitch 3 blade mirage and a 454 with 428 dyno hp.
Any thoughts on the next prop to try? Any experiance with different props and this hull is greatly appreciated.
Thanks for the help.
Jed
PS I did search and my head is spinning!
Any thoughts on the next prop to try? Any experiance with different props and this hull is greatly appreciated.
Thanks for the help.
Jed
PS I did search and my head is spinning!
#20
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Joined: May 2007
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These are the results after the new prop....
I changed from a 21p Mirage Plus three blade to a 22p Brave 1 four blade.
I found with the new prop I would need less RPMs to get the same speed as the original, however, coming on plane I found at around 3,000 RPM the prop would slip and rpms would shoot to 4,000 rpm and then slowly drop as the speed picked up and leveled. At around 3,000 RPM the speed was 35 mph but sometimes at the same RPM the boat would be at 25 mph where the prop seemed to be slipping alot. Not sure why but it seemed off. The other problem the stern seemed to be picking out of the water and the boat seemed less stable.
Any thoughts? Help me out everyone.
I changed from a 21p Mirage Plus three blade to a 22p Brave 1 four blade.
I found with the new prop I would need less RPMs to get the same speed as the original, however, coming on plane I found at around 3,000 RPM the prop would slip and rpms would shoot to 4,000 rpm and then slowly drop as the speed picked up and leveled. At around 3,000 RPM the speed was 35 mph but sometimes at the same RPM the boat would be at 25 mph where the prop seemed to be slipping alot. Not sure why but it seemed off. The other problem the stern seemed to be picking out of the water and the boat seemed less stable.
Any thoughts? Help me out everyone.


