250 not in a hurry?

[Fishysam]

So if I can drive my boat at 4100rpm at a generally normal trim level at 43mph and without moving my foot trim it all the way up for 4500rpm at 42ish mph- question is what is better for the motor, I suspected the higher rpm with the same throttle % BUT then I started thinking will it just be running even more lean/hot?

No porpoising issues, but have read you don't want to bog the motor down at wide open with to much prop

[gehol]

Makes no difference in your example. Should be trimming for best speed at either RPM. Not sure what "normal trim level" means.

[Jtreed99]

^+1. As long as you are propped for the correct WOT rpm range you won’t technically be lugging at any run point that being said I wouldn’t plow water trimmed all the way down on purpose. I’ve always heard stretching it out is good for the motor but some of the guys that get the most out of these motors are the offshore guys. I’m sure those guys are propped to achieve correct WOT range but they do the majority of their running at cruise rpms of 3500-4500 with no issues from running them this way. You would have to believe that the best efficiency point would be just as gehol said, trim for lowest prop slip while cruising.

[EuropeanAM]

Also, 4100 or 4200 are no-where near WOT RPM's on a 250 ProXS. That's CRUISING RPM... simply adjust trim for best speed and ride at the current RPM's.

[Fishysam]

Right on, nitro had it propped right my best speed was a touch over 76 on gps for over a mile with prop slip numbers to good to claim off analog tachometer, not plowing water but optional trim being most of the keel just touching the water so the wake boat wakes are relaxing, say 40-55% trim. But 100% trim lets the rpm climb 300 without more hotfoot, slip is up but the exhaust note clearly changes and just loosens the motor up, so does the ECM adjusts its self for the extra 300 rpm or is this out of my pay grade?

[Savage]

If RPM increases while trimming, and the speed does NOT increase anymore, then the prop IS slipping. RPM reading @ WOT should be observed when the TOP GPS speed is obtained without OVER trimming.

[Fishysam]

Thanks everyone for the input

[EuropeanAM]

If RPM increases while trimming, and the speed does NOT increase anymore, then the prop IS slipping. RPM reading @ WOT should be observed when the TOP GPS speed is obtained without OVER trimming.

+1