2005 Nitro 901 CDX poor performance

[Lilwhirlwind1987]

I have a 2005 Nitro 901 CDX dual console
It has a 150 Efi Mercury serial # 0G803380

21 pitch Tempest
Rpm- 5000 or so.
Speed- 50 mph with just me and my gear.
48 mph with 2 people and gear.

My question is what could be killing my performance ?
This isnt the first engine I've had on this boat and they have all run slower than what I figure they should.
The engine seems to be fine.
Compression on all 6 cylinders are between 110-115 psi

I know this is a heavy boat and the performance will be poor with that little 150 merc. I just figured it should do better than this.

Thanks guys

[WisconsinF]

I think that's all you're possibly going to get.
I can squeeze about 49-51mph out of my 2003 NX882-DC with a 125hp and a 22 pitch and 5200rpm. Just me and 1/4 tank of gas.
Speed isn't important to me at all since all I really do is fish northern Wisconsin lakes with it. Some of my longest runs are only a couple of miles!

[WisconsinF]

I have this chart for Nitro. It says my 822 should run in the high 50s. Shows a 901 at low 60s. I think it's way to optimistic...7-10 mph.

[mpino]

with a 150hp motor your underpowered

a 200hp motor on a 901 is just barely enough power to put it in the mid 60's

if the boat is in good condition and is worth spending money on, (and you intend on keeping it, get rid of the 150 and get a 200hp motor) and add a jackplate or your just waisting your money.

[Sun Fish]

150 is to small for the 901, a 200 will push it mid 60s as said above and it needs every bit of it.

[Lilwhirlwind1987]

I forgot to add I have a 10 inch setback jack plate as well.

With a 21 pitch prop I just figured my rpm should atleast be close to 5400.

To be honest.. with the history of poor performance on this boat with various engines.. I wonder if it isnt water logged from an old busted spot in the hull or something.

Idk just a thought.

I've checked for a hook in the hull.
But it has none.

However it does have somewhat of a hook at the very back of the bottom of the boat.
Like the last 7-9 inches it looks to be hooked ever so slightly. It's very consistent all the way across though, and I THINK..
I remember looking up something or either talking to someone on here that said it was suppose to have that slight hook. Like from the factory or whatever.. maybe not.
It's been a little while.

Does this sound accurate ?
I should upload a picture of this.

Thanks guys

[moetorola]

At this time you got gotta work with what you got.

I can say your RPM's are way to low. Need to get the R's up to at least 5500 at WOT.


What is your P2P?
How is your holeshot?
Do you have a jackplate? What size?

[DMart1]

What is your PTP? If youre only at 5000 RPM at WOT, you're likely overpropped or the motor is too low.

[Lilwhirlwind1987]

At this time you got gotta work with what you got.

I can say your RPM's are way to low. Need to get the R's up to at least 5500 at WOT.


What is your P2P?
How is your holeshot?
Do you have a jackplate? What size?

The hole shot is pretty bad in my opinion. Feels like I'm running a 23 or 24 pitch prop or something, and if I'm loaded with a co angler the hole shot is terrible!
Absolutely aweful.
Takes forever to plane off.

At the moment its 3.5 inches below pad.
I can go another inch though.

I have a 10 inch set back jack plate.
Its non adjustable.

[moetorola]

The hole shot is pretty bad in my opinion. Feels like I'm running a 23 or 24 pitch prop or something, and if I'm loaded with a co angler the hole shot is terrible!
Absolutely aweful.
Takes forever to plane off.

At the moment its 3.5 inches below pad.
I can go another inch though.

I have a 10 inch set back jack plate.
Its non adjustable.

It almost sounds like either your tack is way off, or you have a cylinder down.

Even though you are underpowered I would think you should be able to turn that 21 higher than 5000 RPM.

The engine is being lugged hard, it is like leaving a stop light in 3rd gear.

Need to get that engine close to it's recommended RPM. The RPM should be on the air box under the cowl probably 5600 RPM.

I don't think raising the engine will get you even close to 5500 RPM gain.

[Lilwhirlwind1987]

It almost sounds like either your tack is way off, or you have a cylinder down.

Even though you are underpowered I would think you should be able to turn that 21 higher than 5000 RPM.

The engine is being lugged hard, it is like leaving a stop light in 3rd gear.

Need to get that engine close to it's recommended RPM. The RPM should be on the air box under the cowl probably 5600 RPM.

I don't think raising the engine will get you even close to 5500 RPM gain.

Yesir,

Thank you for the insight .
I checked the compression on the engine and they were all between I think 112-115 psi

Maybe something electrical tho I guess.

Maybe I could run her wide open as fast as she will go.

Then pull the kill switch..? Then look at plugs.

I know if I have a down power issue on a given cylinder, that should give me an idea which one to look at shouldn't it ?

See if ones wet ? Or dry. Or just not like the other 5

I'm thinking it's down a cylinder myself.
After everything I've checked...
It's just the only thing that makes sense.

Or a timing light while I hang off the back of the boat at wide open lol..

Thank you very much for your advice sir