Re: altitude vs horsepower for NA
 

Yeah I went from living in Nebraska to Wyoming and everyone says their cars suck balls here. The only difference I felt in my car was off the launch but after boost I felt no difference till I blew my headgasket. now it doesn't go at all. :-[

Re: altitude vs horsepower for NA
 

ok first of all 10lbs off your car does not equal 1hp, but heres what im thinking as altitude increases hp decreses for NA and FI cars but the rate at which it decreases is much lower in FI applications as there is a compressor feeding in more air, now does anybody have any dynos done at higher altiude of stock cars to compare to the sealevel hp's i know this is kind of dumb but i just want to find out for fun

Re: altitude vs horsepower for NA
 

the dynos around here have told me they use the same formula for both n/a and boosted cars. here is a link to find out the uncorrected horsepower http://wahiduddin.net/calc/calc_hp_dp.htm but right now you are comparing corrected numbers to corrected numbers so change them wont make much sense to change one to uncorrected

Re: altitude vs horsepower for NA
 

Now. Turbocharged cars have a much smaller penalty than N/A or supercharged cars at higher altitude.
Reason is that a turbocharger is atmosphere referenced so a turbo running 1 bar boost at sea level runs roughly 2 bar absolute pressure.
At 0.8 bar absolute atmospheric pressure the turbo car will be at 1.8 bar, still 1 bar above atmospheric but with a bigger pressure ratio. Still only a 10% drop in pressure vs the 20% drop in the atmospheric pressure. And if the turbo car has a closed loop boost controller that's referenced to absolute pressure you can have 2 bar absolute regardless of being at sea level or being in the mountains, within reason. The turbo will have to work harder at higher altitudes (bigger pressure ratio) though so you don't want to go outside it's design limits. A compressor working at a higher pressure ratio means a higher pressure across the turbine too so you do lose some power but it's minimal compared to N/A engines.
It's common to have aircraft engines that are "turbo-normalised", meaning the manifold pressure is kept at 1 bar absolute regardless of altitude. At 0.33 bar atmospheric pressure the turbo will have to work at a pressure ratio of 3.0 to maintain 1 bar absolute in the manifold.
N/A engines really are useless at anything above sea level.

Re: altitude vs horsepower for NA
 

dude even if your at higher altitude blah, blah, blah the crx with its full interior ways about what like a little under or over 1800lbs or something like that and the mustang weights like 3500lbs(depending on which model or engine in it) or over. so the power to weight ratio for the crx is 200hp/1800lbs=1hp/lbs, the mustang has 300/3500lbs=.08hp/lbs, the higher the number is for power to weight ratio the easier its goin to be for your car to get movin. nuff said.