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"Dear Sarah,
What are the kinds of progress that have made turbo charging so usable this decade or so? 'Back then', car reviews will tell you how severe the turbo-lag is (and the subsequent surge in power). Nowadays, many turbo cars seem to not suffer from lag to the extent that reviewers compare the power delivery to that of a N/A engine. Is it better electronic control of... stuff? Materials science? Ground-breaking inventions and improvements?
Thank you.
YW Tan"
"Material choice can greatly influence a turbo’s efficiency with lighter, stronger alloys today reducing weight and air resistance while maintaining strength. Titanium and aluminum alloys are often employed to make the turbine/compressor wheels. BorgWarner’s EFR (Engineered For Racing) turbo features a Gamma-Ti turbine wheel and shaft. Gamma-Ti is more difficult to cast but 50% lighter than its Inconel counterpart which provides better low end response and higher boost at low rpm and can provide higher overall wheel speeds. Gamma-Ti strength actually improves with more heat- it’s weakest at room temperature but during boost and driving conditions, it becomes more ductile and durable. EFR housings are also cast from stainless steel rather than the standard cast iron. This means they are lighter but also way more resistant to cracking under high temperatures. All of these advances in materials lead to greater performance and reliability.
In the past, most compressor wheels were cast aluminum. That's fine when you need cheap and mass produced but it can't offer the same strength or stability as billet aluminum. Cast aluminum products have more defects that promote stress risers, which can lead to wheel failure. To combat this weakness, the blades had to be made thicker and the center hub was beefed up. A step up is a billet wheel. Billet wheels are CNC machined from aluminum stock. They have a more homogenous grain and consistent production. "
CONTINUE HERE
http://www.motoiq.com/MagazineArticl...t-or-Bust.aspx
What are the kinds of progress that have made turbo charging so usable this decade or so? 'Back then', car reviews will tell you how severe the turbo-lag is (and the subsequent surge in power). Nowadays, many turbo cars seem to not suffer from lag to the extent that reviewers compare the power delivery to that of a N/A engine. Is it better electronic control of... stuff? Materials science? Ground-breaking inventions and improvements?
Thank you.
YW Tan"
"Material choice can greatly influence a turbo’s efficiency with lighter, stronger alloys today reducing weight and air resistance while maintaining strength. Titanium and aluminum alloys are often employed to make the turbine/compressor wheels. BorgWarner’s EFR (Engineered For Racing) turbo features a Gamma-Ti turbine wheel and shaft. Gamma-Ti is more difficult to cast but 50% lighter than its Inconel counterpart which provides better low end response and higher boost at low rpm and can provide higher overall wheel speeds. Gamma-Ti strength actually improves with more heat- it’s weakest at room temperature but during boost and driving conditions, it becomes more ductile and durable. EFR housings are also cast from stainless steel rather than the standard cast iron. This means they are lighter but also way more resistant to cracking under high temperatures. All of these advances in materials lead to greater performance and reliability.
In the past, most compressor wheels were cast aluminum. That's fine when you need cheap and mass produced but it can't offer the same strength or stability as billet aluminum. Cast aluminum products have more defects that promote stress risers, which can lead to wheel failure. To combat this weakness, the blades had to be made thicker and the center hub was beefed up. A step up is a billet wheel. Billet wheels are CNC machined from aluminum stock. They have a more homogenous grain and consistent production. "
CONTINUE HERE
http://www.motoiq.com/MagazineArticl...t-or-Bust.aspx