Boost vs altitude compensation

[stevalknieval]

Just reading through a few post regarding boost vs altitude compensation and cannot seem to get my head around it. Can anyone explain to me in relatively simple English? haha. This may be a dumb question, but shouldn't the turbo on a MCX 180 nytro keep manifold pressure a constant 6 PSI regardless of altitude (considering the waste gate rod is set properly). I understand that as altitude is increased, atmospheric pressure decreases, which would in turn make the turbo want to spool faster to get the same boost from this less dense air. Or does the MCX turbo somehow raise boost (using a TCV or other loop feedback mechanism?) while the turbo's RPM is lower to maintain the 180 HP. My set up is a dealer installed MCXpress 180 hp (Robertson Motorsports out of Swiftcurrent SK) on a 2010 Nytro MTX. I am heading to the mountains sometime this week and don't want to think my Nytro is over boosing out of control to the point it will blow up. I was doing some testing and clutching this past weekend at 400m and currently run between 5 to 6 PSI at around 8950RPM. Any help is greatly appreciated!

 

[meskie]

Basically less oxygen available the higher up you go so you need more boost to get the same amount of power as at sea level. It has to do with the available amount of oxygen you are compressing in the engine. The mcx should compensate for elevation. I run mine around 6-7 at home and it will get to 11 up at 10,000ft. Never had a problem. Just watch when you come down from high up that the tcv is working. They will sometimes freeze up under certain conditions and not reduce the boost pressure.

 

[stevalknieval]

Does it compensate for the oxygen deficiency by adjusting per altitude? Or by air/fuel ratio. I'm asking because I don't have an o2 sensor

 

[meskie]

It just adjusts by altitude. Mcx has done the research and testing on it. I just ride mine and don't worry about how it works as long as it does. I watch the boost gauge to make sure it doesn't over boost.

 

[stevalknieval]

Perfect! That's exactly what I was looking for. Thanks alot meskie.