screamin seamen

I have a 87 baja 240 sport alpha drive stock motor.cant get more then 4400 rmp at top speed 56 mph gps. I run 19 pitch prop. up in pitch less rpm same speed.the motor will rev in the drive way. Need advise seems like i could go faster with more rpm.

Randy Nielsen

iTrader: (4)

If the motor is all stock there should be a tag on the valve cover or flame arrestor cover that tells info on the motor,spark plugs,gap,timing,idle speed and wot rpm. that should be 42-4600 rpm.

picklenjim

Assuming it's a 330. Sounds like it's right where it should be.

Kenthegreenkeeper

My brother has an '88. You're in the ballpark with speed/ rpms if it's 330 hp.

rpm vs pitch: you're getting more rpm, but you are "pushing" less water.

astar77350

I have an 88 and had a similar problem with mine when I first got it. I would think with that size prop you would get more rpm. I have a 24 p 4 blade. I found that I wasn't trimming my motor up enough to reach a higher rpm. When you take the boat out next time, set the throttle to 50% and then begin adjusting your trim on your drive. Watch and listen, your rpms should change. It takes some finesse but eventually you will find the "sweet spot" for best speed and rpm. My 88 will hit 62 with my 4 blade.

A.O. Razor

First things first. What is your drive ratio? Your numbers don't add up at all. If a 1.5 your slip is -6%, and that is as impossible as levitation. Even with a 1.36 gear, your slip is 4% and that is still more or less impossible for that style of hull. Find out where it goes wrong. Either your prop, your tach or gps is off.

What make and model prop are you running? What is the state of the bottom?

Randy Nielsen

iTrader: (4)

I must have missed something when I commented las time. Is this a big block or small block cause I thought the bravo came out in 88 or 89 but if this is an alpha that would make me think small block & alphas had I think3 gear ratios according to engine. 260hp 350 should be 1.47 gear ratio I believe . 19p sounds about right maybe a 21p depending on weight & hull design, is the motor tired?

A.O. Razor

The 454/330 was an Alpha package before the B1. Plenty of those around. Actually the gears at that time was called 1.5. Whether or not they were 1.47 or 1.5 I do not know, but they were changed to 1.47 later on.

As I posted. How can a prop be right, when the rpms and speed gives a slip number of neative 6%? Something's way off here.

Boater8987

I owned a an 87 Baja Sport 240 with the alpha 330 big block set up. It came with a 19 pitch prop. I may be wrong, but from what I remember the gear ratio was not 1.5 It was a lower numerical number like 1.26 -1.32 -1.36 or something like that making it a taller gear ratio. Merc stating it was a stronger gear set for the BBC/ alpha package. It turned around 4400 rpm at 56-58 mph. Like I said I may be wrong it was a long time ago. LOL

MASOMAN

iTrader: (1)

Boater8987 You are correct all the 454 alpha packages from merc came with the 1.32 gear ratio.