600hp Dissapointed top speed and take off!
What's up guys! I have a 1989 Carrera 24ft. With a 502 punched out to 509 est. 600 HP. I did not build the engine so i don't have exact specs of build. The problems I am having are frustrating me. Of course first thing that comes to mind is a prop problem... I have tried 4 different props. The one that works best for me is a Rev4 21p on a bravo 1. Rpms are at 5100 but top speed is only 60mph gps trimmed out. I do live in Utah at an elevation of 4500ft. I would really like to get 65 to 70 out of it. Motor runs like a top so It's not a problem with tuning.
The second problem I am having is prop blowout. When i go to plane out if i gas it at all above 2500 rpm until I plane the prop blows out rpm goes up and boat slows down. I tried a 21p mirage plus but it got worse so i am thinkin maybe a 5 blade would help me out. What's ur guys opinions on it? Thanks in advance! |
Maybe your X dimension is too high?
And without really knowing the engine, there is no guarentee of HP. |
Sorry to say...your prolly 100 hp off in your guess. Most people think they have more than they actually do. :drink:
|
what were you doing before?? prop/rpms/speed before engine rebuild.
my 454 mag 385hp can push a 21p M+ or 21 rev 4 to the rev limit.. Have you tried a 23 rev 4? |
Originally Posted by Stormrider
(Post 3458435)
Maybe your X dimension is too high?
And without really knowing the engine, there is no guarentee of HP. But u are right there is no way I can verify HP output. No engine dynos in Utah either. |
Originally Posted by nailit
(Post 3458439)
what were you doing before?? prop/rpms/speed before engine rebuild.
my 454 mag 385hp can push a 21p M+ or 21 rev 4 to the rev limit.. Have you tried a 23 rev 4? |
Originally Posted by tinman565
(Post 3458437)
Sorry to say...your prolly 100 hp off in your guess. Most people think they have more than they actually do. :drink:
|
Prop issue.
I had my 26' boat with 454 Merc. mag. Bravo 1, mirage 23" prop. clocked at 69.3 You should do low/mid 70's with a 502 and try 24-26 props. 502's have enough torque and a 24' boat is light enough. |
Originally Posted by PARADOX
(Post 3458473)
Prop issue.
I had my 26' boat with 454 Merc. mag. Bravo 1, mirage 23" prop. clocked at 69.3 You should do low/mid 70's with a 502 and try 24-26 props. 502's have enough torque and a 24' boat is light enough. http://s1186.photobucket.com/albums/...1.jpg&newest=1 http://s1186.photobucket.com/albums/...1.jpg&newest=1 |
I hate to say it but the fact that you're only turning a 21P prop to 5100 tells me you're down on power.
Personally I would try a 23P Rev4 and see what happens. But I'm guessing similar speeds at lower rpms. Are you getting full timing advance? Jetted correctly for your altitude? |
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