Faster Four: GM Patents a Better Two-Stage Turbocharger

Steph Willems
by Steph Willems
faster four gm patents a better two stage turbocharger

General Motors wants better performance from its boosted engines, so it headed to the patent office with a design for a new two-stage turbocharger — one that eliminates the drawbacks of the existing setup.

According to a document published by GM Inside News, the General filed the patent on May 19. The design (mated to a four-cylinder engine) isolates the low-pressure and high-pressure turbines, calling on one or the other (but not both) at different engine speeds and loads.

In a conventional two-stage setup, both turbines operate simultaneously at low to mid engine speeds, with only the low-pressure turbine working at high engine speeds. The two sides are never fully isolated, which compromises low-end performance.

Like a parent dealing with squabbling kids, GM decided to separate the two. In its design, the high-pressure turbo connects to the exhaust manifold via a high-pressure inlet duct, with the low-pressure unit connected to that channel via a low-pressure inlet duct. Depending on engine speed, an ECU-guided actuator located in the exhaust manifold opens opens the high-pressure inlet duct while closing off connecting channel, or vice versa.

The design aims to lower pumping losses while boosting the efficiency of both turbines. According to the patent, “maximum available enthalpy is given to the LP stage (low pressure turbine) in full power operation and to the HP stage (high pressure turbine) in maximum torque operation.”

Expect to see the turbo lag-reducing technology added to GM’s four-cylinder engines in the future, with the high-output 2.0-liter being a likely starting candidate.

[Image: General Motors]

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  • Kvndoom Kvndoom on Jun 26, 2016

    I for one do NOT welcome our new four cylinder overlords. (at least not in "performance" vehicles)

    • See 7 previous
    • TMA1 TMA1 on Jun 27, 2016

      kvndoom, don't forget you had to sign a software license when you bought the car. The electronic governor and ECU don't belong to you. Modify it, and you can expect to hear from some OEM lawyers.

  • Thegamper Thegamper on Jun 27, 2016

    Seems like a similar setup to what Mazda is doing in the new CX-9 2.5T. Not being an engineer, not sure what the distinctions are.

  • Teddyc73 A resounding NO. This has "Democrat" "Socialism" "liberalism" "Progressivism" and "Communism" written all over it.
  • Jeffrey An all electric entry level vehicle is needed and as a second car I'm interested. Though I will wait for it to be manufactured in the states with US components eligible for the EV credit.
  • Bob65688581 Small by American standards, this car is just right for Europe, and probably China, although I don't really know, there. Upscale small cars don't exist in the US because Americans associate size and luxury, so it will have a tough time in the States... but again Europe is used to such cars. Audi has been making "small, upscale" since forever. As usual, Americans will miss an opportunity. I'll buy one, though!Contrary to your text, the EX30 has nothing whatsoever to do with the XC40 or C40, being built on a dedicated chassis.
  • Tassos Chinese owned Vollvo-Geely must have the best PR department of all automakers. A TINY maker with only 0.5-0.8% market share in the US, it is in the news every day.I have lost count how many different models Volvo has, and it is shocking how FEW of each miserable one it sells in the US market.Approximately, it sells as many units (TOTAL) as is the total number of loser models it offers.
  • ToolGuy Seems pretty reasonable to me. (Sorry)