250 Pro XS Operating RPM

This topic has 8 replies, 8 voices, and was last updated 15 years, 3 months ago by stickwurm.

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March 14, 2011 at 1:02 am #366520

em beez
Participant

I have a question to those that run Pumas with a 250 Pro XS and Fury Prop. At what revolution per minute should I try to manage the engine at running at top end. Also, where could I expect it to revlimeter at? I just finished breaking the engine in today at Lake of the Ozarks and ran it over 5000 rpms for short durations. I achieved 77.5 mph at top end but did not want to push the engine any harder than 5800 rpms. The water pressure was 25 psi at this point. Please give me your recommendations on what is considered top end without hitting the revlimeter. I am sure that the engine will revlimeter if it is pushed too hard.

March 14, 2011 at 1:26 am #366524

Bass Cat Boats
Keymaster

mbeckler, Let it rip! The rev limiter has a warning before it shuts down and the tag on your serial number of the engine should have the exact RPM that the limiter kicks in.You really can run it till the little subtle beeps pop in there. Plus you will have warning indicators if you have NexSysLink gauges.

March 14, 2011 at 5:25 am #366527

JSLAW
Participant

At 77 mph and 25 PSI i doubt your going to find the rev limiter unless you become airborne to allow the prop out of the water, i would think you could still probably raise the JP a little. I usually will try to maintain around 5800-5900 on the RPMs while running right around 80. I havent messed with the JP on my Pumma yet, as i really have not seen a need to, its running 77 loaded with pasenger and with only me and half tanks right around 80, and Ive yet to have the pedal mashed to the floor for a two mile run or longerto really see what she has, and am consistently in that MPH range with about 18 psi. I beleive Max RPM is 6000 though Merc has removed the max RPM on the 250 sticker, i know on my 200 opti it was there and stated 5850 as max RPM on the little white sticker.Last edited by JSLAW on March 14th, 2011, 3:58 pm, edited 2 times in total.

March 14, 2011 at 12:08 pm #366529

SeaPointBakers
Participant

I recently finished breaking in my new 250xs and even though I wasnt the one driving at the time. We hit 80.8 on the GPS, im not sure where the RPMs were since I wasnt driving but that is when we heard the beep for the rev limiter.

March 14, 2011 at 4:23 pm #366532

steeler34
Participant

Just a little note. I bought a Mercury engine analyzer/engine data reader (really a Mercury tool) and when I read my 225 ProXS adn a couple of other buddies engines, on the scanner there is a “prop Speed” and a rev limiter. The prop limit is a few hundred RPM lower than the limiter. I ASS-U-ME that they want you to run at WOT abit lower than the engine limit. Of course that prop limit might be the horn you get. My 2 centsMilton

March 14, 2011 at 5:50 pm #366534

gchagler
Participant

The prop speed rpms should have nothing to do with the engine rev limiter as the rpms will differ between the two b/c of the gear ratio. I think the ratio is 1.72 engine revolutions to 1 revolution of the propshaft.

March 14, 2011 at 6:09 pm #366538

steeler34
Participant

Again, not sure but 1.72 at 5800 Engine RPM is only about 3400. That sounds right as I doubt you would turn the wheel at that high an (5800) RPM.Maybe BCB or a mercy mechanic can tell us waht the prop speed means.Milton

March 14, 2011 at 8:13 pm #366542

Gary Hollander
Participant

http://www.csgnetwork.com/marinepropcalc.html

March 14, 2011 at 11:54 pm #366545

stickwurm
Participant

Gary, that formula got me scratchn the head, it dont even hve hp or weight ? Was close anyway. I have always been told to run about 5900. I turn 6050/ 81.9, go ahead an drp the hammer!
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