High altitude boost

abuelo ralliart · Aug 26, 2009, 07:15 PM

Hey guys,
Im planning to shortly reinstall the turbo in my RA. The this is that I live in Mexico City, that's 7500 feet above sea level so atmosferic pressure is 3.5 psi less than at sea level (11.2 vs 14.7 psi).

I am planning to boot somewhere between 8 psi, so when I measure 8 psi on my boost gauge the ABSOLUTE pressure entering the manifold will be 11.2+8= 19.2psi inestead of the 22.7 psi you will find at sea level with the same measured (relative) 8psi.

So my question is: could I got to 11.5 psi measured by the boost gauge with the same safety of a 8psi measured at sea level?

Thoughts, comments?

hackish · Aug 27, 2009, 07:57 AM

The 4G49 seems to take to 12psi OK with proper tuning. In theory you probably would be OK with 11.5 but again this is dependant on tuning. 3 years ago I tuned a car for Pike's Peak and ended up modifying the boost profile in a similar fashion. The driver said it made a big difference when he was close to the end of the race.

-Michael