40 mph uphill? Other Armada or Titan TVs?

boggerr wrote:

richclover wrote:

Huntindog wrote:
Not really totally true. Although a turbo MAY not keep all of it;s ability to increase power at high altitude, it will ALWAYS do better than a naturally aspirated motor. There are some variables in turbo systems on motors.... A variable vane turbo is one. The other is sizing. Many turbos control excess pressure by means of a wastegate that bleeds off excess pressure.... at altitude where there is less pressure, it will bleed off less if at all.

boggerr wrote:
Where is everyone getting the info that a turbo is the answer? A turbo diesel at higher elevations is going to lose turbo efficiency. Less air, less combustion temps = laggy turbo,

RPM’s is the answer. Run higher RPM’s on hills and watch your gauges.

...

I’m not disagreeing that a turbo will do better than a N/A eninge but I want the OP to understand that having a turbo is still going to feel the effects of higher elevations and downshifting is going to play a big factor on a turbo enonge.

Yes, VGT turbo and turbo sizing makes a huge difference but still need the higher RPM’s to keep those turbos spooling. As far as wastgates go, they are not opening at higher elevations cause of less air and less boost which equals to less horsepower.

So you think a turbo diesel truck or car is making the same HP at sea level vs one at higher elevation? What did that turbo plane do for RPM’s

The short answer is “yes”. I haven’t researched the engineering but I expect that my Turbo Cummins will make rated horsepower on I80 at 8000+ feet elevation in Wyoming. Same on I95 in Florida, but with little or no turbo boost.

My 235 hp Lycoming aircraft engine was rated at 2400 rpm and red lined at 31” manifold pressure. With the simple, manually controlled wastegate it would produce close to rated horsepower to 20,000’.

Agreed, rpm will affect turbo output, but given an appropriate control system and normal operating rpm ranges, I wouldn’t think it would affect automotive engine output that much. Peak torque output is certainly affected by rpm, IMHO.

Here’s an excerpt from the Wikipedia article on turbos:

“... A reduced density of intake air is caused by the loss of atmospheric density seen with elevated altitudes. Thus, a natural use of the turbocharger is with aircraft engines. As an aircraft climbs to higher altitudes, the pressure of the surrounding air quickly falls off. At 18,000 feet (5,500 m), the air is at half the pressure of sea level, which means that the engine produces less than half-power at this altitude.[20] In aircraft engines, turbocharging is commonly used to maintain manifold pressure as altitude increases (i.e. to compensate for lower-density air at higher altitudes). Since atmospheric pressure reduces as the aircraft climbs, power drops as a function of altitude in normally aspirated engines. Systems that use a turbocharger to maintain an engine's sea-level power output are called turbo-normalized systems. Generally, a turbo-normalized system attempts to maintain a manifold pressure of 29.5 inches of mercury (100 kPa).[20]...”