Pikes Peak Highway

Cars do lose power. Going up is not too bad. Controlling your speed coming down can be harder for most "flatlanders".

Check out the Mt Evans road. It is slightly higher than Pike's.

Do you have to stop periodically to let air out of the tires?

People would have trouble breathing. Does the O2 sensor compensate to an extent?

No, it's not that much of a change

Most people have no problem, but do notice a slight "shortness of breath". There is a situation called "altitude sickness" which is normally only a problem if, say you arrive at Denver airport, and go straight to high altitude without some time to adjust.

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As part of a car's ECM system, they do contribute, along with others like the "knock" sensor, to adjust the fuel and spark as needed. In general, fuel injected cars do much better than older carburetor versions. I once drove a 1973 Plymouth w/318 V-8 (in 1975) up Pike's, had pedal to the floor, doing 10 MPH !!

most modern injector systems have an air pressure sensor for atmosphere as well as the intake manifold. that is the primary input for compensation, and the oxygen sensor will fine-tune from there.

I have driven both Mt Evans and Pikes Peak recently (last couple years) and my vehicle (2000 silverado z71) had no issues. I didn't let air out of th e tires either. I have heard, probably on this ng, you can lose up to 3% o f your total hp for every 1000' of elevation. No idea if that's true or no t and/or limited to naturally aspirated cars only. My truck would burn rub ber on asphalt at sea level and I couldn't break traction in the dirt at 14

000'. So if that logic is correct, my truck has 285hp stock and at 14000' would lose 42% of it's hp leaving me with 165.3hp...

What happens is people pull over to the side to look at the view and make out.

I did it in a rental, and it wasn't bad, the road is actually very well maintained. Modern cars with feedback control systems will run fine. Old cars with carbs will run rich and lose power somewhat. People who lived in Denver used to use reduced size jets for better performance up there. But feedback control and injection has eliminated all that.

--scott

All normally aspirated cars, whether they use carburetors or fuel injection, will lose power and it has nothing to do with whether or not they are keeping the fuel/air mixture correct. Turbocharged and supercharged cars have the advantage.

Well, we have two different kinds of loss here. Yes, there will be some loss just due to the lower air pressure. If you go up to 10,000 feet, the air pressure drops to about 20 inches of mercury instead of 30 at sea level, so it's like having a throttle that only opens 2/3 of the way there.

This isn't an enormous loss for most cars, since you wouldn't normally be going anywhere near full throttle driving up a dirt road on a mountain anyway.

The second kind of loss is the loss due to the rich mixture, and that is more significant when you're driving a car subject to that.

--scott

The time I drove a 64 mustang to the grand canyon, it felt like I had half the power. That's about 7000 ft. My 77 datsun ran just ok in the high desert of 2-3k ft. It had an altitude switch, no feedback injection. I think the set point was 3k ft. For the switch.

Greg