high to low altitude question

[mrbill812]

2000 Glastron Gx205 (20?)
5.0 gxi Volvo penta engine
5 blade 21p proper
This is my first trip from Colorado to Table Rock Lake Missouri with this boat. At home in Colorado the prop pushes the boat along great and right at WOT. My concern is at lower altitude will I take a chance of exceeding the engine RPMs during skier pull out or do I just watch the RPM?s and tell any other drivers, sister and spouse to not go full throttle.
I was thinking of purchasing a cheaper 3 blade 22 p for the trip, but if not really needed I could better spend the money on a travel cover. I was also told there is an RPM limiter on this engine, so not to worry about it, but I?m still worried.
Any suggestions?
Thanks mrbill

 

[steelespike]

Re: high to low altitude question

What is the elevation change? It would seem you could simply watch the rpm.
You would gain about 3% for each 1000 ft reduction in elevation.

 

[Tail_Gunner]

Re: high to low altitude question

Mr Bill....your fuel injection system does have the ability to adapt to altitude changes. Do not be surprised if there is little or any difference...while it cannot make up for the lack of oxygen the engine may have leaned out enough to create more power and better econ. Marine motors run incredibly rich which does lower power and econ somewhat..It also has a rev limiter which will cap your rpm to 5000....i doubt very much you will be pulling someone at 5000 rpm..but then maybe not...

 

[mrbill812]

Re: high to low altitude question

Thanks for the reply Tail gunner, I think your thoughts are right on the money. Never hurts to ask and your reponse made me laugh! Your right no one in my group will be skiing that fast... LOL

mrbill

 

[shrew]

Re: high to low altitude question

Carb jetting is changed for elevation changes. The jet size dictates the amount of fuel delivered to match the amount of air being delivered. As you decrease eleveation you create a lean condition where the fuel delivery is fixed for a given RPM, but the air density changes (increases). This essentially increases the air in the air to fuel ratio. For fuel injection this should not be an issue.