Best engine at altitude
06-23-2015, 04:14 PM
#31
Aircraft turbochargers and automotive turbocharger systems are designed with significantly different design goals...
One example:
In aeronautical applications, turbo lag isn't an issue... You are operating in a more constant range of RPM's that also change fairly slowly (no gear changes, no start/stop). They are designed to optimize power in a limited range of RPMs but a large range of air densities. These usually means big turbo's that can move lots of air but aren't particularly responsive.
In automotive applications, turbo lag is extremely important.... Lots of start/stop, quick acceleration, gear changes, and a much larger variation in RPM's (and a comparatively small variation in air density). These means much smaller turbos that move less air but are much more responsive.
While an aircraft turbo system will not struggle to mantain high absolute psi at 12,000 feet and much higher, turbo's like the ones in our trucks can't provide the same absolute PSI consistently at high elevations... Even if they had the theoretical capacity (which they likely don't), they would get too hot and overheat the intake charge, so the software doesn't even try to have them keep the same absolute boost at high altitudes... They significantly reduce power loss at higher altitudes, but don't even come close to eliminating it entirely.
One example:
In aeronautical applications, turbo lag isn't an issue... You are operating in a more constant range of RPM's that also change fairly slowly (no gear changes, no start/stop). They are designed to optimize power in a limited range of RPMs but a large range of air densities. These usually means big turbo's that can move lots of air but aren't particularly responsive.
In automotive applications, turbo lag is extremely important.... Lots of start/stop, quick acceleration, gear changes, and a much larger variation in RPM's (and a comparatively small variation in air density). These means much smaller turbos that move less air but are much more responsive.
While an aircraft turbo system will not struggle to mantain high absolute psi at 12,000 feet and much higher, turbo's like the ones in our trucks can't provide the same absolute PSI consistently at high elevations... Even if they had the theoretical capacity (which they likely don't), they would get too hot and overheat the intake charge, so the software doesn't even try to have them keep the same absolute boost at high altitudes... They significantly reduce power loss at higher altitudes, but don't even come close to eliminating it entirely.
Last edited by pfbz; 06-24-2015 at 02:44 AM.
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Kenferg1 (06-23-2015)
06-23-2015, 06:36 PM
#32
Senior Member
Ecoboooost!