Engine RPM 1700 max

[knersus4711]

I had my 2019 R31CB trailer-ed from Florida to Lake Tahoe. The engine performed fine in Florida but now I get a maximum of 1700 RPM. Could it have to do with the 6,200 feet altitude? I have read somewhere that prop pitch and size might have to be changed to allow the Turbo to spool up? What is the standard size prop that this Vessel is shipped with (I did not measure mine before launching it).

 

[lproulx]

If it's a turbocharged engine, it should still produce rated power at high altitude. If not, power will be greatly reduced. My aircraft engine will only produce 50% power at 7,500 ft.

Larry

 

[BB marine]

If you are not seeing a code and the engine doesn’t seam to be going into a derate. I would suspect that the turbo is not spooling up. Possibly a stuck turbine wheel from coking. If you run at lower rpm this can cause this. Normally it will still function when normal use but if it is fouled and then the boat sits for a while the coking or carbon gets harder and the turbo wheel exhaust side gets stuck. Just a guess, it has happened to other tug owners with D4.

 

[knersus4711]

If it's a turbocharged engine, it should still produce rated power at high altitude. If not, power will be greatly reduced. My aircraft engine will only produce 50% power at 7,500 ft.

Larry

I also fly a turbo airplane (Cessna T210) but I think the problem with the boat may be that the engine needs to reach certain RPM for the Turbo to kick in. Water resistance does not diminish like air at altitude, I guess.

 

[knersus4711]

If you are not seeing a code and the engine doesn’t seam to be going into a derate. I would suspect that the turbo is not spooling up. Possibly a stuck turbine wheel from coking. If you run at lower rpm this can cause this. Normally it will still function when normal use but if it is fouled and then the boat sits for a while the coking or carbon gets harder and the turbo wheel exhaust side gets stuck. Just a guess, it has happened to other tug owners with D4.

What would be the potential remedy for the coking?

 

[gwishon]

See this thread....

viewtopic.php?f=5&t=15038

Gordon

 

[knotflying]

If it's a turbocharged engine, it should still produce rated power at high altitude. If not, power will be greatly reduced. My aircraft engine will only produce 50% power at 7,500 ft.

Larry

But remember, in a plane you can lean or enrich fuel mixture based on altitude. I think it may be an altitude issue, but I would think that with all the computer info there would be an automatic adjustment of the fuel. Perhaps a call to a local mechanic will help. I just find it odd that the boat was fine until lake Tahoe. My first question when an issue arises is, what did I do last or what is different now than the last time? 90% of the time the answer to those questions is the root of the problem.

 

[BB marine]

If you are not seeing a code and the engine doesn’t seam to be going into a derate. I would suspect that the turbo is not spooling up. Possibly a stuck turbine wheel from coking. If you run at lower rpm this can cause this. Normally it will still function when normal use but if it is fouled and then the boat sits for a while the coking or carbon gets harder and the turbo wheel exhaust side gets stuck. Just a guess, it has happened to other tug owners with D4.

What would be the potential remedy for the coking?

The thread that Gordon posted should explain the procedure.

 

[CAPTCRUNCH]

I wonder if 2,500 miles of bouncing around on the highway didn't redistribute gunk/debris in the fuel tank so it is now restricting supply to the engine.

 

[gwishon]

In turbocharged engines, the loss of power due to air density loss (at altitude) is much less than in a normally aspirated engine, but there is still some loss. As knotflying said, adjusting the air/fuel mixture can influence the power produced but we don’t have that option on our tugs without adding expensive aftermarket fuel management systems. That said, the inability to rev past 1700 rpm is indicative of another issue, either a coked turbo or fuel delivery problems, in my opinion. Altitude induced power loss should not prevent the engine from revving to its max rpm.

Gordon