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    • Cadillac introduces a 4.2 liter direct injected twin scroll twin turbo V8 with forged internals and 627 lb-ft of torque

      Well, about time! Finally a domestic producer joins the twin turbo V8 ballgame and Cadillac is leading the charge. The new engine does not have a designation yet but what we do know is it is a strong entry into the segment.


      550 horsepower and 627 lb-ft of torque points to a design with plenty of low end muscle. As is the trend the new V8 features dual twin scroll turbochargers situated in the valley of the motor. Yes, this is the same as BMW, Audi, Porsche, and Mercedes.

      Let's look at the specs:

      Type: 4.2L twin-turbocharged DOHC V-8 with Active Fuel Management, direct injection and stop/start
      Bore and stroke (in / mm): 3.39 x 3.55 / 86 x 90.2
      Block configuration: 90-degree V-8 with five cross-bolted nodular iron main bearing caps; with provisions for jet-spray oil cooling
      Block material: A319 sand-cast aluminum with pressed-in iron liners
      Crankshaft: Forged steel
      Pistons: High-strength hypereutectic aluminum with friction-reducing polymer skirt coating
      Connecting rods: Forged steel with floating wrist pins
      Cylinder heads: Cast aluminum “hot V”-type with 36mm intake valves and 29mm sodium-filled exhaust valves
      Compression ratio: 9.8:1
      Valvetrain: Dual overhead camshafts; four valves per cylinder with and dual independent valve timing
      Firing order: 1-5-4-3-6-8-7-2 (1-4-6-7 with Active Fuel Management engaged)
      Ignition system: Coil-on-plug
      Fuel delivery: Direct injection with dual electronically controlled 59mm throttle bodies
      Turbocharging system: Two low-inertia twin-scroll turbochargers with electronically controlled wastegates and water-to-air intercooling
      Max boost: 20 psi (1.38 bar / 138 kPa)
      Horsepower (hp / kW @ rpm): 550 / 410 @ 5700 (CT6 V-Sport) – est.
      500 / 373 @ 5000-5200 (CT6) – est.
      Torque
      (lb.-ft. / Nm):
      627 / 850 @ 3200-4000 (CT6 V-Sport) – est.
      553 / 750 @ 2600-4600 (CT6) – est.

      The rods are forged so this should take quite a bit of boost without breaking a sweat. From the factory the motor is already pushing 20 psi.

      What models will get the new turbo V8? For now just the CT6 and CT6 V-Sport are listed. It is not known if the CT6 has hardware changes which reduce the stated horsepower and torque. One assumes it is more of a change than just a tune. If Cadillac copies the BMW and Mercedes approach, they will go with single scroll turbos rather than twin scroll turbochargers for the lower output version of the motor.

      What else does it have? Water-to-air cooling and dual throttle bodies. The motor has solely direct injection and not dual-injection which is disappointing but perhaps performance versions utilized in other GM products will go to dual-fuel injection:

      Direct fuel injection is used to optimize efficiency and performance. With direct injection, a higher compression ratio — 9.8:1 — is possible because of a cooling effect as the injected fuel vaporizes in the combustion chamber, reducing the charge temperature to lessen the likelihood of spark knock. A pair of engine-mounted, camshaft-driven high-pressure fuel pumps supplies fuel to the specialized injectors at 5,075 psi (350 bar), with each pump supplying fuel to one bank of the engine.

      Active Fuel Management (AFM), also known as cylinder deactivation, imperceptibly shuts down half of the engine’s cylinders in certain light-load driving conditions to enhance fuel economy. Unique deactivating rocker arms are used for each of the four valves of the cylinder being deactivated.

      Dual overhead camshafts and a virtually silent chain-driven valvetrain contribute to the smoothness and the high output of the Cadillac Twin Turbo V-8, while dual independent continuously variable valve timing helps deliver optimal performance and efficiency. The dual independent system, which allows the intake and exhaust valves to be phased at different rates, promotes linear delivery of torque with near-peak levels over a broad rpm range, and high specific output (horsepower per liter of displacement) without sacrificing overall engine response or drivability.

      Oil jets located in the block are employed for performance and temperature control. Four jet assemblies in the engine drench the underside of the pistons and the surrounding cylinder walls with an extra layer of cooling, friction-reducing oil. The jets reduce piston temperature, allowing the engine to produce more power without reducing long-term durability.

      Variable-pressure oiling system. A variable-displacement vane oil pump enhances efficiency by optimizing oil pressure as a function of engine speed. With it, the oil supply is matched to the engine load rather than the linear operation of a conventional, fixed-flow oil pump. The engine uses 10 quarts of General Motors’ dexos2 0W40 motor oil.

      Stop/start technology shuts down the engine when the vehicle stops momentarily, such as at stoplights. The engine automatically restarts when the driver takes their foot off the brake. An auxiliary battery powers electric accessories such as the climate system, power windows and radio during engine restarts.

      The main question really remains as to what other GM vehicles will get this motor. Cadillac won't just keep it for themselves, will they? A GM Performance SUV or Truck is practically begging for this engine.

      Well done Cadillac.

      This article was originally published in forum thread: New Cadillac Exclusive motor! TT V8 started by subaru335i View original post
      Comments 14 Comments
      1. CobraMarty's Avatar
        CobraMarty -
        4.2L = 256 CID

        550HP at 20psi is only about 245hp naturally aspirated which is only 0.96hp/CID.
        And only 5700 rpm. 4.2L V8 DOHC should be a 7000 rpm engine.

        Sorry but I'm not that impressed. There must be a lot of restrictions in that packaging.
        I will give them that the 627 TQ is impressive
      1. Stevenh's Avatar
        Stevenh -
        Click here to enlarge Originally Posted by CobraMarty Click here to enlarge
        4.2L = 256 CID

        550HP at 20psi is only about 245hp naturally aspirated which is only 0.96hp/CID.
        And only 5700 rpm. 4.2L V8 DOHC should be a 7000 rpm engine.

        Sorry but I'm not that impressed. There must be a lot of restrictions in that packaging.
        I will give them that the 627 TQ is impressive
        Hopefully this iteration will end up in an SUV first and explain the stump puller power curve and the performance version comes down the road.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by CobraMarty Click here to enlarge
        4.2L = 256 CID

        550HP at 20psi is only about 245hp naturally aspirated which is only 0.96hp/CID.
        And only 5700 rpm. 4.2L V8 DOHC should be a 7000 rpm engine.

        Sorry but I'm not that impressed. There must be a lot of restrictions in that packaging.
        I will give them that the 627 TQ is impressive
        Well this is just the V-Sport version. It's going to be moving a big and heavy all wheel drive sedan.

        The actual 'V' version should knock our socks off.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Stevenh Click here to enlarge
        Hopefully this iteration will end up in an SUV first and explain the stump puller power curve and the performance version comes down the road.
        The Escalade I suppose would be a good candidate.

        Cadillac e-mailed me back and said the engine is exclusive but that they can't comment on future projects.
      1. SpeedLimit?'s Avatar
        SpeedLimit? -
        Any chance this is a variation of the v8tt rumoured to be in the mid engine vette?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by SpeedLimit? Click here to enlarge
        Any chance this is a variation of the v8tt rumoured to be in the mid engine vette?
        Not according to this: https://www.boostaddict.com/content....8-power-LT7-V8
      1. Blown6's Avatar
        Blown6 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Well, about time! Finally a domestic producer joins the twin turbo V8 ballgame and Cadillac is leading the charge. The new engine does not have a designation yet but what we do know is it is a strong entry into the segment.


        550 horsepower and 627 lb-ft of torque points to a design plenty of low end muscle. As is the trend the new V8 features dual twin scroll turbochargers situated in the valley of the motor. Yes, this is the same as BMW, Audi, Porsche, and Mercedes.

        Let's look at the specs:

        Type: 4.2L twin-turbocharged DOHC V-8 with Active Fuel Management, direct injection and stop/start
        Bore and stroke (in / mm): 3.39 x 3.55 / 86 x 90.2
        Block configuration: 90-degree V-8 with five cross-bolted nodular iron main bearing caps; with provisions for jet-spray oil cooling
        Block material: A319 sand-cast aluminum with pressed-in iron liners
        Crankshaft: Forged steel
        Pistons: High-strength hypereutectic aluminum with friction-reducing polymer skirt coating
        Connecting rods: Forged steel with floating wrist pins
        Cylinder heads: Cast aluminum “hot V”-type with 36mm intake valves and 29mm sodium-filled exhaust valves
        Compression ratio: 9.8:1
        Valvetrain: Dual overhead camshafts; four valves per cylinder with and dual independent valve timing
        Firing order: 1-5-4-3-6-8-7-2 (1-4-6-7 with Active Fuel Management engaged)
        Ignition system: Coil-on-plug
        Fuel delivery: Direct injection with dual electronically controlled 59mm throttle bodies
        Turbocharging system: Two low-inertia twin-scroll turbochargers with electronically controlled wastegates and water-to-air intercooling
        Max boost: 20 psi (1.38 bar / 138 kPa)
        Horsepower (hp / kW @ rpm): 550 / 410 @ 5700 (CT6 V-Sport) – est.
        500 / 373 @ 5000-5200 (CT6) – est.
        Torque
        (lb.-ft. / Nm):
        627 / 850 @ 3200-4000 (CT6 V-Sport) – est.
        553 / 750 @ 2600-4600 (CT6) – est.

        The internals are forged so this should take quite a bit of boost without breaking a sweat. From the factory the motor is already pushing 20 psi.

        What models will get the new turbo V8? For now just the CT6 and CT6 V-Sport are listed. It is not known if the CT6 has hardware changes which reduce the stated horsepower and torque. One assumes it is more of a change than just a tune. If Cadillac copies the BMW and Mercedes approach, they will go with single scroll turbos rather than twin scroll turbochargers for the lower output version of the motor.

        What else does it have? Water-to-air cooling and dual throttle bodies. The motor has solely direct injection and not dual-injection which is disappointing but perhaps performance versions utilized in other GM products will go to dual-fuel injection:

        Direct fuel injection is used to optimize efficiency and performance. With direct injection, a higher compression ratio — 9.8:1 — is possible because of a cooling effect as the injected fuel vaporizes in the combustion chamber, reducing the charge temperature to lessen the likelihood of spark knock. A pair of engine-mounted, camshaft-driven high-pressure fuel pumps supplies fuel to the specialized injectors at 5,075 psi (350 bar), with each pump supplying fuel to one bank of the engine.

        Active Fuel Management (AFM), also known as cylinder deactivation, imperceptibly shuts down half of the engine’s cylinders in certain light-load driving conditions to enhance fuel economy. Unique deactivating rocker arms are used for each of the four valves of the cylinder being deactivated.

        Dual overhead camshafts and a virtually silent chain-driven valvetrain contribute to the smoothness and the high output of the Cadillac Twin Turbo V-8, while dual independent continuously variable valve timing helps deliver optimal performance and efficiency. The dual independent system, which allows the intake and exhaust valves to be phased at different rates, promotes linear delivery of torque with near-peak levels over a broad rpm range, and high specific output (horsepower per liter of displacement) without sacrificing overall engine response or drivability.

        Oil jets located in the block are employed for performance and temperature control. Four jet assemblies in the engine drench the underside of the pistons and the surrounding cylinder walls with an extra layer of cooling, friction-reducing oil. The jets reduce piston temperature, allowing the engine to produce more power without reducing long-term durability.

        Variable-pressure oiling system. A variable-displacement vane oil pump enhances efficiency by optimizing oil pressure as a function of engine speed. With it, the oil supply is matched to the engine load rather than the linear operation of a conventional, fixed-flow oil pump. The engine uses 10 quarts of General Motors’ dexos2 0W40 motor oil.

        Stop/start technology shuts down the engine when the vehicle stops momentarily, such as at stoplights. The engine automatically restarts when the driver takes their foot off the brake. An auxiliary battery powers electric accessories such as the climate system, power windows and radio during engine restarts.

        The main question really remains as to what other GM vehicles will get this motor. Cadillac won't just keep it for themselves, will they? A GM Performance SUV or Truck is practically begging for this engine.

        Well done Cadillac.
        You should get your facts straight before you post false information. This motor is not fully forged, the pistons are CAST

        And I quote: ‘hypereutectic aluminum’

        Please correct your original post and stop misleading.
      1. BlackJetE90OC's Avatar
        BlackJetE90OC -
        Click here to enlarge Originally Posted by Blown6 Click here to enlarge
        You should get your facts straight before you post false information. This motor is not fully forged, the pistons are CAST

        And I quote: ‘hypereutectic aluminum’

        Please correct your original post and stop misleading.
        Did he say fully forged?

        He clearly posted the specs in his thread.

        Crankshaft: Forged steel
        Pistons: High-strength hypereutectic aluminum with friction-reducing polymer skirt coating
        Connecting rods: Forged steel with floating wrist pins
      1. Blown6's Avatar
        Blown6 -
        Click here to enlarge Originally Posted by BlackJetE90OC Click here to enlarge
        Did he say fully forged?

        He clearly posted the specs in his thread.
        The OP stated the ‘internals are forged’. But they are not, the piston (which is an internal part) is not forged.
      1. BlackJetE90OC's Avatar
        BlackJetE90OC -
        Click here to enlarge Originally Posted by Blown6 Click here to enlarge
        The OP stated the ‘internals are forged’. But they are not, the piston (which is an internal part) is not forged.
        Engine does have forged internals...crankshaft and connecting rods. As stated in the specs posted in sticky's post, yes the pistons are hypereutectic aluminum.

        You are the one reading as "fully forged", it never states that.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Blown6 Click here to enlarge
        You should get your facts straight before you post false information. This motor is not fully forged, the pistons are CAST

        And I quote: ‘hypereutectic aluminum’

        Please correct your original post and stop misleading.
        How do you mislead people by posting the exact specs from GM?

        You need to get your eyesight checked. I didn't say fully forged, you did.

        Some people...
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Blown6 Click here to enlarge
        The OP stated the ‘internals are forged’. But they are not, the piston (which is an internal part) is not forged.
        The title says it has forged internals. Which it does...

        The exact specs are listed. Nobody is being misled here except by you.

        Better luck nitpicking next time.
      1. subaru335i's Avatar
        subaru335i -
        Click here to enlarge Originally Posted by SpeedLimit? Click here to enlarge
        Any chance this is a variation of the v8tt rumoured to be in the mid engine vette?
        Like sticky posted, the leaked 3D models for the mid engine vette show no hot V configuration. The intake ports are in the center like a normal old V8 and the turbos are mounted to the sides.
        I would also hope that the vette gets a higher revving maybe slightly bigger displacement (more than 5L) motor. The torque in this is great but this is the "sporty" engine not the "race" engine.

        It sounds like this is cadillac exclusive as well so I would think it will go into the Escalade but not other GM products.
      1. subaru335i's Avatar
        subaru335i -
        Click here to enlarge Originally Posted by CobraMarty Click here to enlarge
        4.2L = 256 CID

        550HP at 20psi is only about 245hp naturally aspirated which is only 0.96hp/CID.
        And only 5700 rpm. 4.2L V8 DOHC should be a 7000 rpm engine.

        Sorry but I'm not that impressed. There must be a lot of restrictions in that packaging.
        I will give them that the 627 TQ is impressive
        It is clearly not tuned/designed for max hp up top. It could easily be spun much higher but they wanted a mountain of torque for this application. The CT6 is their biggest car like the S class or 7 series, it doesn't need high revs.

        CT5-V will be much more impressive.