prop testing new motor 259 convincer

[theresa]

motor dynoed at 519hp 5600 rpm tried a hydromotion 21p qiv balanced prop awsome responce out of hole all the way though wot 5500rpm reached 65mph any suggestions for better top end speed

 

[hotdaddy27]

Maybe jump up a pitch or two and try a Bravo 1? I assume 5600 is your limiter?

I am not sure what that hull should do with 500HP+, but if you can squeez upper 60's or even 70 out of it that sounds respectable to me!

Good luck.

HD

 

[keith4216]

23 mirage or 24 bravo 1

 

[theresa]

tried a 24 p 4 blade unknown brand wot4600rpm at 63mph slow to plane off motor can go 5600

 

[Gimme Fuel]

Those rpm and pitch #'s don't sound right for 519 hp. My tired 415 hp 502 spun a 24p Bravo I to 4900 (on a 253...not a whole lot of difference). Did you dyno the motor or was it bought with the boat? something isnt adding up here. My friend's 259 with a Crockett 454 (about 440 hp) ran best with a labbed 25 mirage at 70 mph. These hulls respond well to props with lots of bow lift like a mirage or a worked Bravo 1 with the diffuser ring cut (settles the stern) and added cup (provides more bow lift).

If you are only getting 4600 rpm with a 24p, that prop is too tall. How far are you trimming the drive up when you are running at WOT?

 

[Big Red]

Everybody is missing a key question, whats the torque numbers from the dyno. 519hp is good but without a higher torque number its useless.

To spin a 24 the torque needs to be 550-600 with 519HP

 

[ross]

big red is right, i am spinning a 26p bravo1 to 5300 with a 500hp gm zz502= 565 ft lbs of torque
sorry thats on a 251 if it helps....

 

[hotdaddy27]

Everybody is missing a key question, whats the torque numbers from the dyno. 519hp is good but without a higher torque number its useless.

To spin a 24 the torque needs to be 550-600 with 519HP

Yep, torque is important....so what does the dyno sheet say???

 

[theresa]

sorry took so long to get back out changing props torque sheet says 478.3 torque @5700 519 hp tried a maraige 23 pitch 5300rpm wot 68.9 mph gps not bad out of hole lost some response though out half tank of gas two people think maybe a 21 pitch ?? or is that it top speed . sheet says 490 torque @5400rpm

 

[jazzy]

those numbers put your slip at 10.5% which is pretty respectable assuming you have a 1.5 ratio drive sounds like thats all there is for that motor two questions for you are you running stock cast manifolds? if so they are killing your power at upper rpms, also what ignition are you running if it is the stock 502 mag mercruiser ignition i may be thinking that the 5300 you claiming is really 5200 and you are hitting your rev limiter

 

[Comfort Travel]

Sorry to change the talk, but I have a 25.1 convenser with a 502 and headers with a mirage plus 25P at 4900 about 69 to72 GPS. But I was thinking changing my X - diamention from 6" to a littel less any input.

 

[Big Red]

Sorry to change the talk, but I have a 25.1 convenser with a 502 and headers with a mirage plus 25P at 4900 about 69 to72 GPS. But I was thinking changing my X - diamention from 6" to a littel less any input.

Leave the x alone it will only backfire in your face with the little power your running.

 

[Comfort Travel]

I have a restored 1989 25.1 convensor W/RB 502 at about 475HP. I run a 25P Mirage Plus. runs about 4900 RPM at 69 to72 MPH GPS. I was thinking about changing my X - diamention from 6" to 4" or 5" has anyone tryed this, I hear that it adds about 4 to5 MPH.

 

[Comfort Travel]

Any outher hints because this winter I would like to pick-up about 5 MPH for the run I am plaing for a trip down the Mississippi from about Minnesota to St.Louis or so and would love to have more Checkmates along.

 

[stclairriverblaster]

weigh your boat and make sure the foam isnt soaked adding a ton of weight.
or your motor isnt cammed right and your way outta your power band. a actual dyno print out would help.