Quote:
Originally Posted by soutthpaw
  In celerbration of my 200th post, I decided to start another thread  
being that I am at 6000 ft and that there are obvious differences between Flatlander and Mountain Man tuning, I would like to get more input on this subject...
seems to play a role in Fueling and injection timing as there even separate settings for sea level and altitude in the programming... even for WOT shifting...
The Turbo in general is supposed to offset the effects of altitude found in naturally aspirated engine. So I am wondering why the altitude parameters are needed...
Oh, and at what elevation does the altitude parameter start to function? is that adjustable?????
For Jack I think the parameters would be even more significant for the Gassers being they are naturally aspirated |
I can talk about what I've highlighted:
Any kind of air compressor can only boost pressure relative to the outside (ambient) pressure. At sea level, the compressor is going to push more air into the engine than it can at 6000+ feet. (Up on Pikes Peak, the effect would be even more pronounced). So, you are still getting the effect of a change in altitude even with the blower and, the fueling will have to be adjusted for it.
To give you "numbers", at 18,000 feet, (only 4,000 above Pikes Peak), you are at 1/2 standard sea level atmospheric pressure (14.7 psi), so at 18,000, the pressure is only 7.35 psi. A good turbo might give you a 40% boost, I think. At sea level, this means your intake "sees" about 20.6 psi, which really improves the engine's power. But, if you could take that turbo to 18,000 feet, the same 40% boost gives you a total of only 10.29 psi, much less than an unblown engine at sea level.
A turbo DOES allow you to run your engine at a higher altitude than an unblown one, which is why reciprocating aircraft engines might have them. But, as with all things, there is still an upper limit.
- Jack