2021 Mercury 175 pro xs power issues

[RoughriverRick]

<3B042350>

2021 Mercury 175 pro xs power issues
I bought a new 175 pro xs to replace my old yamaha proV 150. I dont seem to have the power I should have. Ive tried several different props and I am waiting for another prop to ship to the dealer to try. I currently have a 21 pitch 14.5 dia prop on the boat. I cant only get about 5400 rpm and 52 mph. My yamaha was turning 5700 rpm with a 23 prop and getting 54. I had a prop dealer tell me that he has had several people come to him with the same issue and he said I was doing better than most. My question is am I screwed. Any help would be greatly appreciated

[BassinB]

I don't have any recommendations for you besides to have the dealer check to make sure engine is reaching 100% throttle. I am interested in any additional information on the topic of performance from the 175 engine as well. Have heard many of the similar things your dealer has. One guy I know repowered a boat that had a 150 xr6 with a new 175 pro xs and lost 2 mph after trying 7 props, different engine heights and confirming it was reaching 100% throttle. He isn't impressed.

[EuropeanAM]

Please take a moment to review the Announcements at the top of the Forum, and be sure to provide the Required Info (serial number) when posting. Thanks!

First and foremost- do you have a HOTFOOT or a Hand-Throttle?

EXACTLY what propeller are you running currently, on what boat, and do you have a jackplate installed?

[RoughriverRick]

Ok here goes,
serial number is 11750001A 2021 model 175 pro XS
Yes I do have a hotfoot that was dealer installed when the motor was purchased
The motor is on a 6" setback jack plate and the center of the prop shaft is 2.5" below the pad when both are level. the rooster tail is about even with the top of the cowl at full throttle, full up trim
Current prop is tempest plus 21p x 14.5"
The boat is a 1997 charger TF295 foxfire 19.5"
The dealer has worked well with me and taken the boat out a couple different times and put it on the analyzer and assures me I am getting wide open throttle.
Any suggestions would be greatly appreciated...

[EuropeanAM]

Serial number is formatted: Digit, Letter, Six Digits (examples: 2B123456, 3B123456).

[RoughriverRick]

3B042350
The number in the post above is the model number, sorry

[EuropeanAM]

Did you have that 6" setback on the Charger with the previous engine? I'm questioning both the mounting height AND the setback on your setup.

What are your actual SMARTCRAFT RPM's, and GPS speed at WOT?

Have you tried LOWERING the engine?

[RoughriverRick]

Yes I had the same jack late on the previous motor. My mobile view says I'm running 5380 rpms and 52 mph at wide open throttle. I actually started out with the motor 2 bolt holes lower than it is now. But i have lowered it about 3/8 of an inch to get it where I am now. 2.5" below pad..

[EuropeanAM]

If the engine is running correctly, and there is ZERO question as to whether or not the engine is reaching 100% Demand Linear, I would try a 19 Pitch prop ONLY to see if the RPM's spin up better. Of course, note speed as well, but we're essentially checking to see if the engine "can" spool up to RPM's.

I have my own suspicions in regards to the jackplate, but we really need to know the results of the above before going there.

[RoughriverRick]

Ok, I am have difficulty finding a prop. The dealer has ordered a 19x14.65 but its 8 weeks out. I found an aluminum one 19x14.5 today, pick it up this afternoon. I'll let you know what happens.

[EuropeanAM]

Diameter comes first... so that's a 14.5 x 19.

[ford4wd08]

Have had no power issues with my 175 Pro XS 4 Stroke.

I will say my engine came alive when I added the 6 inch jack plate to my Triton. I can really get the rpms now. I'm getting ~5900 to 6000 rpms with my 22 tempest at 2.5" below pad on my Triton.

[RoughriverRick]

If the engine is running correctly, and there is ZERO question as to whether or not the engine is reaching 100% Demand Linear, I would try a 19 Pitch prop ONLY to see if the RPM's spin up better. Of course, note speed as well, but we're essentially checking to see if the engine "can" spool up to RPM's.

I have my own suspicions in regards to the jackplate, but we really need to know the results of the above before going there.

Ok, I tried a 14.5x19 black max prop today. Its aluminum but its all i could get my hands on.
Rpms where between 5980 and 6010
Mph was 45.5
Water line was even with me at the console, not really on plane.

[EuropeanAM]

Ok... so it is capable of spooling up to RPM's, despite a lack-luster performance from the aluminum prop.

I personally think YOUR boat would have been better suited with the engine direct on the transom (rather than on a jackplate). Given the weight difference between your old ProV and the V6, that 6" setback moves the "moment of inertia" quite a ways aft.

Once you get your new prop in, play with the height a bit (note: may only 1/4" changes at a time and record results each time). Start LOWER (around 3.25" below if possible) and work your way up, 1/4" at a time.

Continue raising in 1/4" increments until one of the following occurs:

-RPM's increase, but speed DECREASES

-Water pressure drops below 15 psi @ WOT

-Unsafe, or Undesireable Handling Characteristics develop.

[lpugh]

Some how I can not imagine that charger running right at 2.5 in p to P

[fly by night]

Unbelievable to me that you are only getting 45.5 mph. Hang in there and I am sure with Don and others assistance the problem will soon be resolved. Just a matter of finding the correct combination for your nice boat!