lack of oxygen

[krick3tt]

While watching a news report on an air show in CO I noted that one of the reasons that the pilots have issues with their planes here was the lack of oxygen.
The pilot said that his plane makes about 450 HP at lower altitudes and that up here at + 10,000 feet the HP is just about 200 HP. This is detrimental to his
ability to perform some stunts and he really has to watch what he is doing.
Makes sense...It took me about a year of living here to get used to less air at just 5000 ft.
Then I thought about my driving in the mountains and why my little 80 HP engine might not do so well either...does my HP go down significantly at altitude with
less air? 'Things that make you go Hmmmmm.'

[undysworld]

Morris,
Yeah, it does decrease the power. In order to keep the right air/fuel mix, you have to put in smaller jets. They allow less gas to flow, which is just like lifting your foot on the accelerator.

[berger]

My Ural was the same when I drove to San Fran last year. Going through Colorado, I hit elevations of 14,000 feet, and the bike didn't like it. I was way too rich for the elevation.

[krick3tt]

Thanks for the input.

I know that the jets are numbered according to their size. What numbers correspond to large and small and where are they indicated on the jets?

I have rebuilt the carbs on Mogs and they can't be that much different than the ones on pinzgauers. After I rebuilt the Mog carb it ran better so I
also rebuilt the fuel pump...it was even better running after that. I see some more work in my future.

[djw]

does my HP go down significantly at altitude with
less air? 'Things that make you go Hmmmmm.'

Depending on the density altitude (pressure altitude corrected for temperature) you're down in the neighborhood 22-25% in HP at 10K ft. All the smaller jets do is correct the mixture back to optimal given the air density is less at altitude. They don't return the missing hp lost from altitude and neither does FI.

That's why turbo chargers were put on normally aspirated airplane engines so that they could run sea-level performance (or pretty close) because they restored sea level density up to about 18,000ft since planes typically run at a fixed power setting most of the time.

Or you could just fit a turbo and put the density back to what you'd have at sea level and leave the jets alone I have no idea whether you could do this on a pinz, or whether the TD would perform as such at altitude.

[krick3tt]

Sounds like using a cannon to kill ants. Lest's see...jets cost somewhere between $13 and $56 and they fit in the same hole that the other ones come out of.
Turbo...lots and lots of money and where does it go?

I am going to stick with a simple approach to this issue. Rebuild the carbs, set the timing and make sure I use clean gas. Oh yeah, and just stay to the right
going up hills. Might look into the fuel pump as well, maybe even get a spare one of those so if it goes out away from the garage a change out would be my move.
Not sure about the cost of a spare fuel pump...remember hearing about one from a VW that fits. Have to look into that.

When on long trips I use lead additive and it does seem to make a difference.

Thanks for the responses to my question.

[audiocontr]

DIY turbos are pretty common in the import scene. I pieced one together for a CRX early in my career, but this is where fuel injection was very nice.

A pinz would need to function like an old Corvair. You would create a new manifold from the carbs, to the turbo, and then back into the block. Keep PSI low due to heat issues and expect loads of lag.

I'd think Jims fuel injection would be step one.

[krick3tt]

Keeps getting better $$$$$. If I go with FI then the engine needs a good overhaul...new pistons and barrels, bearings, cam shaft, etc.
Looks like a new (rebuilt) engine with turbo and EFI. Might as well get a new pinz.

[eToothpaste]

Sorry to kick up an old topic, but which jets did you pick, Krick3tt? Did you see better MGP or performance ... or anything? I've noticed mine smells pretty rich and is quite thirsty (9 MPG on my first tank).

I'm about 1000 ft lower than you, but the air gets tinner, not thicker, in the places where I take my pinz.

[Twin Pinzies]

I run mine at elevations between 9,000-13,000 ft. above sea level with stock jets. They do run a little rich but otherwise do quite well.