Q: turbocharger sizing, diesel vs. gasser
Q: turbocharger sizing, diesel vs. gasser
(OP)
I have noticed turbochargers for diesel applications to have their turbine wheel diameter to be more generously sized as their petrol/gasser engine counterparts. Diameter increase of turbine wheel over compressor wheel varies from about 10% up to 30%.
Gasser turbo's have somewhat equally sized compressor and turbine wheel diameters.
Can someone please shed light into this what factors are at play, when comparing diesel vs. gasser?
Furthermore, why on some diesel applications the turbine wheel is a mere 10% larger than compressor wheel, whereas sometimes the size difference is quite remarkable?
RE: Q: turbocharger sizing, diesel vs. gasser
rmw
RE: Q: turbocharger sizing, diesel vs. gasser
RE: Q: turbocharger sizing, diesel vs. gasser
As for "low-end" power/torque, again the turbo has been the one of the biggest contributors as to having a power curve with this low end power--With engines rated at 1800 to 3000 RPM max ( 25-30+++ PSI at WOT) , we see boost starting to rise rapidly from 1000 rpm and up with 15-20+ PSI in the 1500-1700 RPM ranges on many engines..
Newer waste gate technology, new or variable shaped air turbo inlets, and new ideas in turbo air mapping has allowed new designs to give this low-end boost while controlling max boost pressures at high speeds---
In a nutshell, turbos do not just engage or "turn on"--They come up to speed based on design and the power that the engine needs to deliver whether that is at a low RPM below peak torque, in mid-RPM's at peak torque, or at WOT..
Tony
Tony Athens
http://www.sbmar.com
RE: Q: turbocharger sizing, diesel vs. gasser
However, due to the lower compression ratio a gasoline engine has more enthalpy left in the exhaust gas (more pressure and temperature). This would at least partially explain why the turbine can be downsized accordingly on gasoline engines.
And as far throttled operation is concerned: Turbos shouldn't come up to speed when the throttle is closed or partially closed on a gasoline engine regardless of turbos used. Otherwise a turbocharged gasoline engine would not be very efficient. Or why 'boosting' a throttled air flow unless perhabs for some race application?
RE: Q: turbocharger sizing, diesel vs. gasser