sound right?

[boatn70]

i was looking at a 26 hydro q4 prop, the guy said his 25 checkmate (not sure which one) would only turn it to 4800 at 69 mph. his motor was a 502 dynoed at 548hp.

doesnt sound right to me......

im hoping my setup will be the same hp and that seems low, he runs a 23 hydro at 5200 and 72mph.

is there a base rpm gain per hp, based on the same prop,
for example:
i ran a 22 hydro at 4600 at 56 mph then...
a 22 hydro at ??????

any guesses? does this question even make sense??

kevin

[boatn70]

i was looking at a 26 hydro q4 prop, the guy said his 25 checkmate (not sure which one) would only turn it to 4800 at 69 mph. his motor was a 502 dynoed at 548hp.

doesnt sound right to me......

im hoping my setup will be the same hp and that seems low, he runs a 23 hydro at 5200 and 72mph.

is there a base rpm gain per hp, based on the same prop,
for example:
i ran a 22 hydro at 4600 at 56 mph then...
a 22 hydro at ??????

any guesses? does this question even make sense??

kevin

[illMATTic]

all motors have different power bands. sure his motor was dynoed at 548, but at what rpm? maybe the 26 was too much for it and was not letting it get to its full hp range. or he could be way off on what he is telling you.

[jrumon]

boatn70...
I always had the best MPH with Merc Mirage SS 3-blade props on my 21' & 23' Bravo drive boats. I wouldn't run a 4 blade unless your really running high x-dimension or a heavy hull... The 4 blades ARE better for mid-range crusing, but for top end numbers the 3 blades prevail.

What is the combo your building...

[boatn70]

i did try the 23 mirage and mirage+, the mirage ran best top end but for everyday usage the four blade corrected my porpoising....it seemed to give good stern lift and not as much bow lift, bow lift doesnt seem to be the problem, at least with old motor.

[boatn70]

heres the setup"
502 block
gm iron ported heads (flowed well!!)
custom grind cam from chris straub
emi exhaust
BG 850 carb
Dart intake
Morel lifters
crane gold rollers
8.9:1 compression (calculated so far, need to cc the cumbustion chambers yet!)

by all calculations and programs i should be at 540-550 hp. will dyno and tune first so will know the numbers. with the cam thats going in it should be puttin out between 500 and 600 ftlbs all the way from 4400-5600 rpm (obviously thats just a projection but chris the cam guy knows his stuff on this so im gonna try it!!)

i guess ill wait on the prop till i can run one first!!

[jrumon]

What hull is this in and is it factory x-dimension (prop shaft to bottom of hull)???

[bdusted440]

Kev is running a anaversiry edition convincer 242 I think with a stock bravo.Ran good with the old motor I cant wait to run him with his new one. http://checkmate-boats.com/6/ws/,s,8626072361/Graemlins/devil.gif

[boatn70]

as far as i know it is stock dimensions, i havent changed anything.
is there an easy way to measure dimension. drive is off boat, just trans assy on it now, what points could i use?

yes, 242 convincor

[boatn70]

anyone help with checking X dimension?

how can i measure it, the motor and drive is out of the boat right now. HELP!!

thanks
kevin