Powerboat Forums at SpeedWake banner
1 - 9 of 9 Posts

·
Registered
Joined
·
13 Posts
Discussion Starter · #1 ·
24', 454 mag, trim tabs, 22p enertia. Boat planes well and the hole shot is decent however as I hit a top speed run I start porpoising. I still have a click or two left in the throttle but can never go all the way because of the porpoising problem. Best so far is 60 on gps, I think iave a couple more mph's if i can control the porpoising. Someone said I should put spacers in my outdrive but it seems to me that it would make my problem worse. Any help is greatly appreciated.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #3 ·
Agreed, I can trim down to reduce porpoising but lose top end. As i trim up I still climb on speedo but then i porpoise. Want to be able to go full bore without porpoising
 

·
Registered
Joined
·
76 Posts
Well, if you are going for top speed, a 3 blade Mirage Plus should work. I've got a '90 Villian III with a 500+ HP stroker (crankshaft HP) and I'm bumping 70 mph with a 23P Mirage Plus turning 5300 RPMs.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #7 ·
Wow, I would love to hit that type of speed. But as I have a stock setup I cant turn the 23p. Best I can get is 4300rpm. I threw a bravo 1 prop on for giggles and get 55 on gps but the boat handles great and I think I could see better fuel economy as far as cruising is concerned. But with the 22p enertia I can get 60. It just wants to porpoise which is my major frustration. Its a 454 mag motor so Im only getting 335 at the prop. Mods are in store over the winter but for now im a stocker boat. do you have any problems with porpoising? How do you combat it?
 

·
Registered
Joined
·
76 Posts
She porpoises a bit accelerating, but unless I'm going for top speed I use the trim tabs (Bennett ST-12) to flatten it out. I've had her up to 69.7 MPH by GPS, I'm waiting for the motor to finish breaking in (only about 5 hours off the dyno), and an ideal day to see if I can break 70 MPH before I list it in the Microboats thread. I also have my eyes open for a Bravo I prop so I can switch between a 3 blade and a 4 blade.

With the original 7.4L Bravo (300 HP at the shaft) I ran a 21P Mirage (not plus) and would get 56 MPH by GPS.
 

·
Registered
Joined
·
13 Posts
Discussion Starter · #9 ·
Originally this boat came with a 21p when I bought it and i got 57 on the gps. I went to the enertia and got 58. After a tune up and realizing that the plug wires were original (1989) I hit 60 on gps with enertia. I just got this boat this spring and the owner swears that there is less than 150 hrs. on it which I am inclined to believe because of the condition. I put the bravo 1 on it yesterday and the boat is totally different. At 3600 rpms i gps'd at 42 mph. It handles very well and hit 55 top. I will probably run this prop the rest of the season for fuel economy, if there is such a thing. Also, when you hit the throttle the entire boat just seems to "lift" right out of the water. Alot of fun.
 
1 - 9 of 9 Posts
Top