A turbocharger system comprises a first relatively small turbocharger and a second relatively large turbocharger connected in series and an exhaust gas flow control valve. The exhaust control valve has an inlet port communicating with the exhaust gas flow upstream of the first turbine a first outlet port communicating with the exhaust flow downstream of said first turbine but upstream of said second turbine, and a second outlet port communicating with the exhaust flow downstream of said second turbine. The valve is operable to selectively permit or block flow through the first and second outlet ports.
