high altitude useage

[kitokamuro]

on the average how much loss of power can you expect at 6500 ft above sea level

 

[QC]

Re: high altitude useage

I am going to guess 17.8% and then Google . . . stay tuned. Any clues on what you are running?

 

[kitokamuro]

Re: high altitude useage

50 merc on a 14.5 flat bottom on big bear

 

[QC]

Re: high altitude useage

lol, Big Bear is what I was thinking. I lost 4 inches of pitch there . . .

I am reading 4% per 1000 above 1000, so 4 x 5.5 = 22% loss.

 

[kitokamuro]

Re: high altitude useage

yes big bear less than 1 hr drive for me fishing has been good and the boat came with a yearly permit. how much does puddingstone charge for launch?

 

[QC]

Re: high altitude useage

Not sure . . . $12? Launched my tinny there a few years ago. I'm sure they have a site online Where are you?

 

[kitokamuro]

Re: high altitude useage

barstow

 

[QC]

Re: high altitude useage

Silverwood?

 

[kitokamuro]

Re: high altitude useage

Never considered that option. Whats their altitude?

 

[QC]

Re: high altitude useage

3350' http://www.parks.ca.gov/default.asp?page_id=650

 

[kitokamuro]

Re: high altitude useage

thanks, i found it

 

[Silverbullet555]

Re: high altitude useage

I've read of different amounts. Carbed or EFI does make a difference.

But, I'm going to say in the 30-40% range. You'll notice it.

When we used to boat outside Reno and then go to Tahoe we would really feel it and that was only a 2K difference.

At sea level we would run in the mid 50's. At 4500 we would run in the upper 40's. At Tahoe it would take longer to get on plane and seemed to struggle to get there. Many factors including dealing with waves, but we could really feel it. Maybe hit a tipping point at Tahoe.

 

[am_dew]

Re: high altitude useage

With my 17' v-hull runabout with 4 cyl V/P AQ130C, at 4500' elevation I lose approx. 15-20% of my WOT speed and about the same in the time to get up on plane. This is after I've switched to a 17 pitch prop (from a 19 pitch) in order to get my WOT RPMs where they should be. Hate to think what my hole shot would be like if I did not do that.

 

[drrpm]

Re: high altitude useage

At 6,500 feet barometric pressure is 606 mm Hg which is 80% of sea level pressure. As the Oxygen supplied to the engine is 80% of the sea level amount, the engine output should be around 80% of the sea level output.

 

[themaniam1]

Re: high altitude useage

I slip my boat at a lake at 6200 ft (with lousy fishing). When I do down to a lower lake at 4200 ft. I get almost 5 mph faster and hole shots a better. If I jump up to a lake at 7800 (great fishing) then I loose about 3-5 mph and it takes a lot of trim tabs and time to get on plane. My boat is MPI so it auto adjusts to the altitude and my out drive has high altitude gearing. I need to change props if I go below 4200 because I hit max RPM way before WOT but I rarely boat that low and am unwilling to spend $$$ for another set of duel props.

You should be fine. Just don't expect high performance. Enjoy the fishing.