Mercury ProXS specs

[FireKracker50]

I have been looking everwhere or someone who has dyno tested a Merc 225 ProXS. Everyone seems to dis agree on the fuel curves as well as max HP and torque. :(

I have heard that they are rev limited at 6150, also 6350, but the ax RPM range is stated at 6000. Where exactly is the limiter at? :confused:

The next question i have also heard is that after you exceed 5800 the computer severely overfuels t keep exhaust temps down.

Where does the max peak HP fall on the RPM scale on these motors?

What of this is true? i would like to know exactly what RPMs i should shoot for in propping my rig.

Do i prop for 5600 for increased fuel econ, or is that to much strain on the engine? Also would i loose speed potential at that RPM due to the motor not producing enough HP/torque?

Do i prop it to just under the limiter or does the HP curve fall off before that?

:eek:I am just very confused. Any input would be very helpful.

Thanks
cody

[FireKracker50]

bump for info

[FireKracker50]

can't anyone offer some insight to me?

[Wizard]

Cody,

I can tell you I have had a discussion with a friend who works at Merc about the XS motors. The 225 and 250 Pro XS's are similar except for porting and some ECU differences. The full rich at 5800 is not true with the XS's. That is true with the older standard EFI's. The XS's are calibrated exactly through the entire RPM range by the PCM 555 computer based on temp, air density, load etc. They are very smart motors. The hard limiter on these motors should be 6350 but they stop making torque at around 6000. Peak HP and Torque are at 5900 and that is where you want to prop for best performance and fuel economy. Spinning it higher is possible but you won't get more speed unless you have a very light hull. If you prop for 6000 light then turn 5800 with a full load of people your good.

For example my last boat was a Bullet bassboat with a 300XS. It had the same hard limiter and peak power. I had a sport with 1.62 gears. I could run a 26p prop to the limiter at 6300ish with a light load. I could run the exact same speed with a 28p prop to 6000 with the same load. Loaded down with passenger and gas I ran 4mph slower at 5800 with the same 28p prop. Obviously gas and oil comsumption was much better at 5800-6000 than 6300. Why spin the extra 300 rpms if you gain nothing. Again your hull will have alot to do with what you ultimate get but I always try to prop to peak HP and Torque which on the 3L XS's is around 5900. Hope this helps.

:cheers:

[FireKracker50]

THank you so much for the info... that is exactly what i have been wanting to know. I wish i had found that out while i still had my Bullet. I had a Bullet 20DC with 225PRoXS and 1.62 sporty. I turned a 26" B&B TXP-OT4 with added cupping to around 79@5600 (79@5600) Fully loaded with 4 batteries 2 people gear and livewells full. I really wish the prop didn't have that extra cupping. It bit really good and would not blow out. I ran it 2.5" Above pad with 15" Setback and could trim to 8.5/10 i never could get it to run good at level trim. Light it would run up to 82MPH@5800. Stripped i did see 87 some. Aparentlly i should have been running a 25 without added cupping. And that would have put me right where i need in RPMS. Everyone kept telling me to run a 28" Bravo or 28" RE3 or Performer4. But there is no way i could have gotten the RPMs i would have needed out of them.

Now i am running a Cobra Coosa 216 (21' 6", 1610#) with 8" jackplate with the same motor and a 1.75 Torquemaster. I have a 25" B&B TEmpest with added tip cup for bow lift. I can't seem to get it setup right. Its a rocket out of the hole but I am only running 68@5400 and i keep lowering my motor because if i trim above 8/10 i loose speed. I am a full 4" below pad now. Aparently i need to drop in pitch allot. I have a stock 24" Trophy i am going to try running on it.

Sry for the long reply... but what i get from what you say is i need to get my RPMs up allot for peak performance.

Thanks for the help man.

[Wizard]

Yep your Bullet was over propped. Especially with the 1.62's. They are difficult to prop with a heavy fishing load. A 24p Bravo with dual vent plugs would have been the ticket...or a 25 Trophy like you said.

As for you Coosa your close and need a few tweaks. You really need 4 more inches of setback to carry the hull with less trim. Your having to bury your motor to leverage the heavy bow and that's killing your rpms. Move the engine back and you'll use less trim. I think the Tempest is a very good prop for a heavy bassboat. Once you move the motor back you can have a good prop guy adjust the RPMS through pitch, not cup. Good luck! :cheers:

[FireKracker50]

yeah i am wanting a 12" atlas hydraulic as soon as i get the money i think that will help tremendously.