High Altitude Performance

[pduggan]

Boat: 1994 Bayliner Capri 2050CX 20 foot bowrider. Engine: 4.3 L OMC V-6, carb.

I live and boat at 6,200 feet - Lake Tahoe and Donner Lake.

I replaced the stock prop with MWC 992203 Vortex 14 1/2 x 18 four-blade and got considerable improvement in performance.

I have decided not to change gear ratio since I occasionally go down to the flat land and the conversion is expensive besides.

What's next? Are there any engine add-ons available? Re-jet carb?

I would appreciate any advice from the experts.

 

[Aviator19]

Re: High Altitude Performance

I'm not an expert, but in running an engine at higher altitudes I think of leaning the fuel/air mixture to the engine as we do in airplanes with piston engines. As we get higher in altitude the air density reduces so we lean the mixture (reduce the fuel per volume of air) to run the engine more effeciently. So there is not too much fuel going in the cylinders and leaving some behind becuse it all didn't ignite due to the reduction of oxygen volume in the air (high altitudes).

That's how I understand it anyways. And adjusting the prop pitch.

So since we're not flying planes here...Is there a way to do that in boat (or car) engines? The boat didn't come with a mixture knob mounted on the throttle quadrant like in planes lol. I haven't yet taken my boat higher than 1500ft yet, but I know someone who might be taking their's to Big Bear Lake which is around 6750ft MSL sometime.

Thanks in advance.

 

[bruceb58]

Re: High Altitude Performance

I have a house at Tahoe too...it is my vacation house. I wouldn't bother with changing the carb jests since you will be bringing your boat to lower elevations at times.

I trailer my boat up there so I use it at sea level too. It might be different if was up there 100% of the time but since it isn't you don't want to lean it up and then bring it down in elevation and run in a too lean condition.

 

[Haut Medoc]

Re: High Altitude Performance

I agree with BruceB.........
You need a high elevation prop & a low elevation prop....
Don't mess with your carb.......​