Power loss with altitude
12-10-2001, 01:12 PM
#1
Power loss with altitude
We all know that a normally aspirated motor looses power with altitude due to the decrease in air pressure. Three questions:
1) How much power (percentage per 1000 feet of altitude) is lost with normally aspirated motor.
2) Does the 1.8T motor compensate 100% for the decrease in air pressure? ie. Will the 1.8T motor still produce 170hp at 10,000 feet of altitude?
3) What is the effect of altitude on torque and does the turbo compensate for that as well?
Maybe the 1.8T motor is better than the 3.0 normally aspirated motor for people living or routinely driving at high altitudes?
Thanks,
Daniel
Waiting for beige 1.8T avant, quattro, CVT.
1) How much power (percentage per 1000 feet of altitude) is lost with normally aspirated motor.
2) Does the 1.8T motor compensate 100% for the decrease in air pressure? ie. Will the 1.8T motor still produce 170hp at 10,000 feet of altitude?
3) What is the effect of altitude on torque and does the turbo compensate for that as well?
Maybe the 1.8T motor is better than the 3.0 normally aspirated motor for people living or routinely driving at high altitudes?
Thanks,
Daniel
Waiting for beige 1.8T avant, quattro, CVT.
12-10-2001, 01:57 PM
#2
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Re: Power loss with altitude
About 3% power loss per 1000FT altitude without turbo. On boost, turbo brings back most of torque and power. However, because boost does not cut in at initial throttle, the car is slower off the line and you feel more turbo lag.
One side effect for all of this is that when you are not on boost you get better gas mileage because the closed-loop system reduces amount of gas to match available air.
I live at 8500FT in Colorado mountains. My S4 and wife's 225TTC do very well in this environment.
One side effect for all of this is that when you are not on boost you get better gas mileage because the closed-loop system reduces amount of gas to match available air.
I live at 8500FT in Colorado mountains. My S4 and wife's 225TTC do very well in this environment.
12-10-2001, 02:47 PM
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Re: Power loss with altitude
I live at about 6,000 feet and drive to California about 4 times a year. When I've had cars with normally aspirated engines in the past, I looked forward to these trips because my car seemed to transform itself toward hotrod as I dropped in elevation. Not so with the turbos. You notice a little improvement at the low revs at sea level but that's about it. At elevation, the turbo is the great compensator. The air molecules want to spread out as we climb, but the turbo does a nice job of squishing them back into a nice neat package for best possible fuel/air mixture regardless of elevation.
12-10-2001, 04:19 PM
#4
That means that the 220hp 3.0 will have the same power ...
as the 1.8T at 6,000 feet?
If my calculations are correct and assuming 3% power loss per 1000 feet, then:
3.0l N/A 220hp at sea level will relate to
211 at 1,000'
203 at 2,000'
195 at 3,000'
187 at 4,000'
179 at 5,000'
172 at 6,000'
165 at 7,000'
159 at 8,000'
152 at 9,000'
Interesting!
Daniel
If my calculations are correct and assuming 3% power loss per 1000 feet, then:
3.0l N/A 220hp at sea level will relate to
211 at 1,000'
203 at 2,000'
195 at 3,000'
187 at 4,000'
179 at 5,000'
172 at 6,000'
165 at 7,000'
159 at 8,000'
152 at 9,000'
Interesting!
Daniel
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