jcimprover

I have a 2002 with 425hp motor. mirage 22 4 blade. I am getting 61 mph on gps. the dash reads 65. I thought it should go 65-70. Am I dreaming or do I need a different set up. thanks for any input.
jc

bajaboy2004

22 pitch? u could be running at least 25 your definatly not gonna get speed off a 22 pitch on that big of engine, its a 496 ho correct?

jcimprover

Yes its a 496 HO. Next question Which brand? 3 blade or 4 blade? Also It runs right at 5000 rpm now. will I lose rpm with a bigger pitch?
thanks
jc

bajaboy2004

go with a mirage plus and yes the bigger prob u go the less rpm. talk to houston prop he will direct u in the right direction for what u need

502procharger

a larger pitch prop is not the ans. end of story that boat is not going to do 70 with that setup. you are spinning 5k now and you will cut 200rpm per pitch size. going to a larger prop is not the ans.

Chase910

You need a bigger prop and a blower.

Post this in the Baja section and see if other 275 owners run the same speed, 61 sounds correct to me.

articfriends

iTrader: (1)

my boats a 2000 272 (almost identical to yours),when it was stock w/415 hp 502 at our elevation of 600-900 feet,i tried various props(24 pitch 4 blade-rpm'd too low,23 pitch 3blade,23 pitch hydromotive. 60-62 mph fully loaded was all it was good for,64-65 with no passengers ,fuel or coolers (what fun is that anyways). Their are alot of bse'rs and liars when it comes to speed of their boats,especially these baja's,ive never seen a 272 or 25 outlaw that could hit a HONEST 70 mph w/STOCK 502 or 496 let alone a 454 mag,gps is a heart breaker! 61 is probably correct ,your rpm's sound right,maybe with some various props you may find one that will give you 2-3 mph more but pure and simple it is going to take 15-20 horsepower per mph to go beyond that. much more prop and you will be further away from your horsepower peak and only go slower,a 23 pitch will probably give you a little more at the sacrifice of takeoff(most 272's and 25 outlaws come with them stock). What elevation are you at(the higher above sea level the slower your boat will go,do you always fill your tank and do you have any unnecesary weight onboard? My boat was sensitive to weight w/stock engine,if you want a couple mph then you could think about leaving crazy cousin eddie at home and running 1/2 tk of gas,400-600 pounds of gas and extra passengers will translate to 1-3 mph! If you did want your boat to go signifigantly faster loaded the same as you have been running,say 70,your going to need 120-150 hp more,your only going to get that from exstensive modifications to your motor,a supercharger or turbo or a bigger engine. azsm has been developing a intake system and upgrade kit that is supposed to take a 425 hp 8.1 to the 600 hp range,i am skeptical but i guess its possible,but it was as exspensive as a blower kit so it must do something,good luck,Smitty

502procharger

articalfriens, tru dat. it is hard and prob very frusterating to people with simmilar boats not getting the speed "there buddy" is getting with the same power, boat ect. people just tend to lie, fib, or whatever. gps does not lie, 61 with that setup is a good true number. there may be a few more mph there but prob more frustration than it is worth to try 15 diff props, less fuel, ect. it cost big $ to make "real hp" no not what a manufacturer tells you you are at but what a dyno tells you with wet headers and set up the same way it will be in the boat. one of my boats is a 25' switzer v bottom. in the 91 powerboat with a 502 they said 71 in there test. not sure i ever ran that fast with the stock motor. now i run 945 hp and i am fluttering on 100, still have not broken it but i am very very close. so figure it took me 19hp per mph i have increased over stock 415hp. keep in mind it is very easy to drok 5k into a motor and only get a 5-10mph increase. you need to figure out if that is worth it to you or not. you may also be limited by hull design. some hulls will only run so fast. be happy with your speeds or be ready to drop big money. I will not put out there what i have into it but the motor, procharger,drive, and steering system are worth almost twice what i paid for the boat. just something to think about.

502procharger

sorry about the miss spellings i had a few tonight.

Macklin

I believe you have a problem....or they have substatially increased the weight of the 275. I had a 2000 272 with 502 mag. Salt water boat, but she would run 68+ with a 23 Mirage plus. I tried a 22 Bravo and was all over the rev limiter. Ended up running a 24 Bravo because the mid range handling was markedly better than the Mirage. I would see 67+ on a regular basis with that prop. Those are no bullsh*t GPS numbers. I ran right with Reckless' Sunsation 288 and BillR's PQ 280.

Have you checked for hook?