Champs3

Hi guys hoping someone can help me out here a little bit.

I picked up a 91 Baja in the spring the guy before me told me he had it up to 62 mph maybe he was just saying that since he was trying to sell it but ive only got it to 45 on the gps.

I have a bravo 1 outdrive with a 454 different intake nothing special done to it with a mirage 23 prop and i run 4500 rpms.

If anyone needs to know anything else just ask ill try and help out as best as i can

Thanks

Trevor.

phragle

iTrader: (3)

something is definitely up if your spinning 4500 with a 23 and doing 45. Either your tach is off, your gps is off or you have insane slip numbers. what kind of shape is the prop in?? how far are you trimming up??
Do you have 12 fat chicks in the boat??

Champs3

I got 50 mph all by myself with light light fuel but thats all

the prop looks in good condition i thought maybe i had a problem in the drive but one of my friends is a mercruiser mechanic and he said he didnt think anything was wrong with it. I still think thats where my problem is

Ebay Ed

my 272 before i rebuilt it with the stock 454 mpi 310 hp only ran 53 at 4500 rpm with a mirage + 23 pitch

phragle

iTrader: (3)

given an excessive weight guess at 4000 pounds and stock 330 hp theoretical speed would be 65

4500 rpm and 45 mph then gives you a 31% slip,

If your drive was somehow robbing power you would not get the revs.

You either have
A. excessive drag, (trimmed down, major hook, 6" of bottom paint etc

B. Bad prop

C. slipping coupler

1st thing (an esiest) I would try is to borrow a different prop

phragle

iTrader: (3)

Last time I was out, my bottom was coming unglued, my 21 had a ding and I was getting no bow lift so the boat was stuck in glass smooth water and was still doing 50+ with a 330 and 21p I know Im a little lighter but still.....

Point is if your getting the rev's you should be getting the speed. If you were down on power or the drive was somehow binding you wouldn't be getting the revs. However you are getting the revs so something is slipping somewhere.

phragle

iTrader: (3)

The only way it would be your drive (you should have a 1.5) is if somebody threw a drive on with a different ratio. If that's the case borrow a 26 and see what happens.

phragle

iTrader: (3)

These two pages can help


http://www.go-fast.com/boat_speed_predictions.htm

http://www.go-fast.com/Prop_Slip_Calculator.htm

Ebay Ed

phragle clean out your inbox i am about 40 miles south of you

Champs3

okay thanks a lot phragle i will try and get it figured out over the next two night and let you know how it goes, how high do you recommend the trim to be up?