Internal combustion engine with turbocharger system

A turbocharger system for an internal combustion engine having an exhaust port and an intake port comprising:

• a first turbocharger having an operational limit and a first turbine connected to the exhaust port of the engine via a first exhaust line and a first compressor connected to the intake port of the engine via a first intake line;
• a second turbocharger relatively larger than said first turbocharger and having a second turbine connected to said first turbine via a second exhaust line and a second compressor connected to said first compressor via a second intake line;
• a first exhaust flow control means between said first exhaust line and said second exhaust line in parallel with said first turbine for bypassing at least a portion of the exhaust from the engine past said first turbine to said second turbine, said first exhaust flow control means being biased to be at least partially closed but being openable in response to an exhaust pressure increase from the exhaust port such that sufficient exhaust is diverted to said second turbine that said first turbine is prevented from exceeding said operational limit when the operating conditions of the engine increase;
• an intake air control means between said first compressor line and said second compressor line in parallel with said first compressor for bypassing at least a portion of the air from said second compressor past said first compressor to the engine, said intake air control means being biased closed but being openable in response to an intake air pressure increase from said second compressor above a predetermined pressure.
• said first exhaust flow control means is substantially fully open at a predetermined exhaust pressure;
• and
• the turbocharger system further comprises a second exhaust flow control means between said first exhaust line and said second exhaust line in parallel with said first exhaust control means and said first turbine, said second exhaust flow control means being biased closed but being openable in response to an exhaust pressure increase above said predetermined exhaust pressure.