OUTLAW EAGLE MANUFACTURING

[Scottie]

I am running a 406 SBC in my 17' step tech eagle and it's turning a AA impeller @ 4300 RPM. Is it worth dropping a couple impeller sizes to increase my top speed at the expence of 5 or 6 hundred rpm (current top speed is 70 mph on gps on a lake with race nozzle) I am trying to hit the 80mph mark!Which peak, HP or torque on the dyno sheet do I want to operate at?I have heard that guys run there zz4's @ around 5000 rpm, is that where that engine makes its power, or is that where the pump/impeller is most efficient? Any suggestion on what impeller I should use? I am new to this game and unclear on a few things, a little help would be apprecited! The dyno numbers are as follows in that rpm range:

Thanks, Scott

RPM Torque CHP
4000 473 361
4100 472 368
4200 468 374
4300 465 380
4400 460 385
4500 454 389
4600 447 391
4700 442 395
4800 431 395
4900 423 395
5000 415 396
5100 404 393

[Arthur]

You got some decent #'s there already Scottie. My boat came with a 'B' and I switched it to a 'A' for more out of the hole Performance and fuel economy. My original motor was 450hp and with the 'B' I could see 76mph(5400rpm) down river with a 21' HW Sport. Put a ZZ383/425hp in and changed it to a 'A' and the most I'll see is 68mph on a good light day.....+ the ZZ383 only pulls 4700rpm....hope that makes sense.

[RPM]

Scottie , based on your dyno #'s I would have your AA cut down half way to an A cut and try that . I don't see you getting any more speed after getting your engine to turn 4700 . hope that helps

[finally conviced her]

Was that chart that was on the old OEM website very accurate? I see it's not there any more, but it was probably a reasonable reference point for RPM vrs HP for impeller selection.

[RPM]

should of said max thrust from jet with impeller cut to let your engine turn 4700. 4500 max would be a good balance of performance and cruise efficiency . might only be a couple mph gained by trimming impeller . could be speed increases in improving hull , intake etc.

[Scottie]

Thanks for everyone's input on the subject. I think I will try an A cut impeller first to be able to come close to the 5000 rpm mark. RPM do you machine these impellers at your shop? Any tips from anyone for intake modifications? Ex.Airfoil shape grate bars? etc.etc.. Thanks again for your input.


Scott

[big block]

yup good info i need to get up to speed on this stuff as well, zz4 and i get only about 4600 rpm top speed would like more.

[RPM]

Scottie , yes I cut impellers . keep in mind that depending on your alt. and weather cond. your actual hp that your engine can produce may be lower than what you think it's got . probably be derated around 10% or more . guessing you won't be getting to try anything for a while , it's getting down to -30 at night here .