I will be spending the next year or two in northern New Mexico at about 7500 feet - and this has made me reconsider my plans to buy a Cayman, in favor of a turbocharged car like the BMW 335i - it seems stupid to pay a lot of money for a fast car only to lose 30% of the HP at high altitude.

Anyone have any opinions on this?

I know I could install a turbo kit or something, but that would be expensive - and I'm not really comfortable with aftermarket engine mods in general, especially not on a brand-new Porsche.

 

There are few better Porsche roads than northern NM. If you got the BMR you would be totally bummed. Think "lateral G's". The DME compensates pretty well for altitude IMHO.

 

you could get a used cayman and then turbo it!?!

 

Umm... I may be new at this whole turbo thing, but I do believe that turbo cars are the ones that lose the power in altitude. I may be wrong here, but for some reason I dont think I am... (read sig - owned her for 6 years now)

Seriously though, N/A cars are the ones that preform better at higher altitudes, or atleast when you compare them to a turbo car. Turbos require vacuum to boost. Less air = less boost. I boost at about 14 psi where I live (250ft) but when I go to the mountains near me (8-10kft) I boost only about 9-10 psi. You can feel a noticable difference too. The only way to even consider getting rid of this effect is to run off of MAP instead of MAF. Usually MAP requires aftermarket parts and tuning though. Mexican built cars may be different (aka use MAP setup) but its unlikely.

Greg

p.s. One of the first things I'm going to do to my Porsche when I get it is mod it... Why the hell not?!

 

I don't mean to be rude, but I'm pretty sure you're wrong. Turbochargers are used on airplane engines because they're needed to deliver high performance at high altitude.

NA engines lose performance at altitude because the air is less dense, so less air enters the cylinders, so less fuel burns, and you get less power. A turbo or supercharger can compress air to higher densities than ambient atmospheric pressure and let the engine continue to develop the same power it does at sea level.

Of course, if you go high enough, the air will be so thin the engine still start to lose power even with the turbo. But if you take a NA and FI car that produce the same HP at sea level and go climb a mountain, the NA car will lose power steadily while the FI car will be unaffected until you climb past the maximum altitude that the turbo can compensate for - then the FI car will start to lose power as well. It will still be producing more power than the NA car, though.

I think you are thinking of this backwards - turbos are powered by the difference between exhaust pressure and the outside air pressure. For a given throttle setting, exhaust pressure stays the same - but as you go higher, air pressure drops. So the difference between exhaust pressure and air pressure grows - which means a turbo has more power available to work with at altitude, not less.

I don't see why there would be a difference between a system using a MAP sensor vs. a MAF sensor - you can convert between density and pressure if you know the temperature.

 

Get the Porsche period! End of conversation. If you want to talk about driving in altitude more we can but the original question was should you get a turbo car over a N/A one like the Cayman. Between the Cayman and the 335i, Cayman. Way more reliable and a way better drivers car. The 335i is the better DD though from what most people say on here... No matter what you get, post pics!

Greg

 

There will be some power loss, but the computer should compensate and you will still have a thrilling ride!