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The 4.2L, 2020 Corvette ME’s Motor

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Old 03-21-2018, 04:35 PM   #1  
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Default The 4.2L, 2020 Corvette ME’s Motor

Since the Cadillac 4.2L motor thread has been moved out of our section, and as the Markit Engine Forecast, and many other media and “inside knowledge sources” have stated that the the 2020 ME Corvette will have a 4.2L, going to use this thread to compile lots of what we have learned about the Cadillac’s motor specifics that will directly translate/become part of the Corvette’s 4.2L — for one we know is, that GM has been masterful as keeping lots of Corvette parts development costs low by sharing parts with its GM bretheran, e.g. the A6, the A8, the 6.2L, etc. So I hope this thread will be allowed to stay here, and that we can take the tremendous amount of Cadillac 4.2L info we are learning today as, IMO, it is highly probable that 98%+ will be directly transferable, I would argue its internals too, as the Corvette’s ME 4.2L motor. Sure the top lid will not say Cadillac but “Corvette,” it header/exhaust routing will be different, as will some other minor/attendant parts, but its guts and its functionality will be common.

So here goes, starting with the following posts, copies of the media articles we have learned from the cousin Cadillac 4.2 L motor.
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Old 03-21-2018, 04:36 PM   #2  
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Quote:
Originally Posted by MotorTrend
As noted, this 4.2-liter engine, internally code-named GF18, is a clean-sheet design adhering to most of the latest trends. It features a smaller 86.0mm bore and longer 90.2mm stroke, a strategy that favors low-end torque, tolerates higher compression (9.8:1—pretty high for a boosted engine), and leads to improved thermal efficiency. It also enables closer bore spacing—96.0 mm, down from the Small Block’s 111.7 mm, which shortens the block, crank, and all four cams for significant mass savings. Speaking of the crankshaft, it and the eight connecting rods spinning it are made of forged steel and the piston pins feature a diamond-like coating to withstand stress and reduce friction.

The valvetrain includes cylinder deactivation of the number 2, 3, 5, and 8 bores. There’s variable timing on all four cams with 55 degrees of adjustability on the exhaust side and 70 degrees on the intake side. Even better, when switching the engine off (auto stop/start is standard), the intake cams park at a position in the middle of their travel affording no exhaust/intake valve overlap for easier starting and a smoother initial idle. Fuel is always injected directly into the cylinder at high pressure (up to 5,000-plus psi), as there were no operating conditions requiring the addition of port injectors.

The cast stainless steel exhaust manifolds incorporate the housings for the twin-scroll Mitsubishi Heavy Industries turbochargers. The titanium aluminide turbine wheels (half the weight of Inconel) spin up to 170,000 rpm to produce as much as 20 psi of boost that gets relieved via electric wastegates. Bolted directly to the back of each turbo is a 19-liter catalytic converter. These two cats provide all the after-treatment the engine needs—and they greatly complicate the under-hood thermal management, which includes electric fans and water pumps that will continue running long after engine shut-down, following a session of prolonged hard use. An intercooler mounted just above each cylinder head reduces the charge air temperature by 130 degrees F immediately before it whooshes into the outboard intake valves. (Perhaps needless to say, this engine requires premium fuel.)

Two variants of the engine will be offered—each of which will be hand-assembled and personally signed on the Performance Build Center line at the Bowling Green Kentucky Corvette plant. The top version will produce 550 hp at 5,700 rpm and 627 lb-ft at 3,200-4,000 rpm, or 500 hp at 5,000-5,200 rpm and 553 lb-ft at 2,600-4,600 rpm. The difference is primarily in the tuning, with the only mechanical difference being a more restrictive (quieter) exhaust on the lower-output version.
http://www.motortrend.com/cars/cadil...t-look-review/

Last edited by elegant; 03-21-2018 at 04:38 PM.
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Old 03-21-2018, 04:37 PM   #3  
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elegant, you are alluding to this:

https://www.msn.com/en-us/autos/news...mage=BBKwnT2|1
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Old 03-21-2018, 04:38 PM   #4  
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Quote:
Originally Posted by AutoWeek
There’s a new Cadillac V-Sport coming to town, so the company has a new V8. It has less displacement than a small block from its neighbors at Chevrolet at 4.2-liters but uses two turbochargers to pump up the output to 550 hp at 5700 rpm and tractor-pull worthy 627 lb-ft of torque between 3200-4000 rpm. Given the size and strength of the engine, it’s no surprise that this V8 will drink premium gasoline.
Cadillac engineers started with an aluminum-alloy block and bored 86-millimeter diameter holes into it and enough gave it enough depth for a 90.2-millimeter stroke. Iron liners are used to withstand the forces. Both the connecting rods and the crankshaft are forged steel, the later held in place with six-bolt mains. This ninety-degree V engine has a compression ratio of 9.8:1.
Up top, more aluminum-alloy was used for the heads. Cadillac employed a “hot-V” setup, meaning the exhaust exits the cylinders in the valley of the V and fresh air and fuel come outside of it. This allows for both the turbochargers and catalytic converters to lie in the V as well, aiding in quick warm-up to operating temperature. Fuel injection is direct into the cylinder, spraying at 5076 psi of pressure. Unlike your Chevy, this is a dual overhead cam engine with four valves-per-cylinder and fancy valve timing.

The turbochargers are twin-scroll, utilize an electric waste-gate, and spin as fast as 170,000 rpm. To keep the air cool, Cadillac added a 20 kilowatt charge air cooling system for the intake air. It’s a coolant-to-air system that keeps the air as dense as possible. Speaking of cool, this V8 has a 10-quart oil-pan, specified to hold 0W40 weight motor oil. And the pan is designed to leave room for half-shafts on the front axle.
The new Cadillac V-Sport will be the flagship sedan CT6 V-Sport and it will come standard with all-wheel-drive. In between the axles and motor will sit a version of the Ford/Chevrolet co-designed 10-speed automatic transmission called the 10L-90. It’s similar to the gearbox found in the Camaro ZL1. In the CT6, the 10L-90 will have a ratio spread of 7.39, which means high revs off-the-line launch and a most likely sub-2000 rpm freeway cruising speed. And also eight-gears neatly spaced in-between.
A detuned version of this engine will be available in the non-V-Sport CT6 with different software and exhaust plumbing, which reduces the peak output to 500 hp and 553 lb-ft of torque.
http://autoweek.com/article/technolo...n=awdailydrive

Last edited by elegant; 03-21-2018 at 04:39 PM.
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Old 03-21-2018, 04:39 PM   #5  
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Quote:
Originally Posted by TheTruthAboutCars
The company says this [4.2L Cadillac] engine is the first twin-turbo V8 to be installed at the factory between the fenders of a Cadillac. Perhaps the most technically complex production engine ever to emerge from GM, this 4.2-liter is a 32-valve, quad-cam, direct-injected aluminum motor.

At the center of the Cadillac Twin Turbo V8 is a “hot V” configuration that rearranges the conventional layout of the cylinder heads’ intake and exhaust systems in order to mount the turbochargers near the intake ports. This places them in the valley between the heads, which GM officially calls the Valley of Power. Okay, maybe not.

Here are some preliminary specs for you engine nerds, as reported by Automotive News:

Block: 90-degree V8 with five cross-bolted main bearing caps; sand-cast aluminum with pressed-in iron cylinder liners; provisions for jet-spray oil cooling

Bore/stroke: 3.39 in. x 3.35 in. (86 mm x 90.2 mm in logical Metric)

Pistons: High-strength hypereutectic aluminum with friction-reducing polymer skirt coating; forged aluminum connecting rods with floating wrist pins

Compression ratio: 9.8:1

Valvetrain: Dual overhead camshafts; four valves per cylinder

Max Boost: 20 psi

In other applications, this setup helps reduce turbo lag and decrease the engine’s overall packaging size. It also creates a tremendous amount of heat, something The General will have to manage with this new mill. The Cadillac Twin Turbo V8 is teamed with a 10-speed automatic transmission and power is routed to all four wheels.

http://www.thetruthaboutcars.com/201...ngine-keeping/

Last edited by elegant; 03-21-2018 at 04:40 PM.
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Old 03-21-2018, 04:40 PM   #6  
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Quote:
Originally Posted by GM Inside News; Source = Media. Cadillac
At the center of the 4.2L Twin Turbo V-8 is a “hot V” configuration that transposes the conventional layout of the cylinder heads’ intake and exhaust systems to mount the turbochargers at the top of the engine — in the valley between the heads — to virtually eliminate turbo lag and reduce the engine’s overall packaging size.

In a conventional turbocharged engine, the cylinder heads receive the pressurized air charge through ports at the top of the engine and the exhaust exits through ports on the lower outside of the heads into manifolds connected to the turbochargers.

With Cadillac’s innovative hot V design, the intake-charged air enters through the lower outside of the heads and exits through the top inside — where the turbochargers are integrated with the exhaust manifolds — for quick spool-up that translates into more immediate power delivery. The design also allows closer mounting of the catalytic converters, for efficient packaging.

Additional engine highlights:
Twin-scroll turbochargers
Electronic wastegate control
Twin water-to-air charge coolers
Twin throttle bodies
Direct injection
Dual-independent camshaft phasing
Active Fuel Management (cylinder deactivation)
Variable-pressure oiling system
Stop/start technology

Each engine will be hand-built at the Performance Build Center in Bowling Green, Kentucky.

SMALL DISPLACEMENT, LARGE EFFECT

The new Cadillac Twin Turbo V-8’s foundation is an all-new, durable and lightweight aluminum cylinder block that houses an equally robust, lightweight rotating assembly composed of a forged steel crankshaft, forged steel connecting rods and high-strength aluminum pistons.

The crankshaft’s 90.2mm (3.55 inch) stroke complements the cylinder bores’ 86mm (3.39 inch) diameter to give the engine its 4.2L (255 cubic-inch) displacement.

Its comparatively small bore dimension enables the reduction in the size and weight of the pistons, optimizing the engine’s geometry to match the fast-rev capability permitted by the engine’s low-inertia, twin-scroll turbochargers. The result is exceptional responsiveness and immediacy of power across the rpm band.

The turbochargers produce up to 20 pounds of boost (1.38 bar) and are matched with electronic wastegate control for more precise boost management and more responsive torque production. In fact, 90 percent of the engine’s peak torque is available at only 2000 rpm, and it is carried through 5200 rpm for a confident, virtually bottomless power reserve.

TWIN-SCROLL TURBOCHARGERS

The turbos’ twin-scroll design broadens their performance capability, offering quicker response and greater efficiency. Rather than a single spiral chamber (scroll) feeding exhaust gas from the exhaust manifold to drive the turbine on each turbocharger, the twin-scroll design has a divided housing with two exhaust gas inlets and two nozzles to drive the turbine. Generally, one of the nozzles contributes to quicker response and boost production, while the other contributes to overall peak performance.

Each of the engine’s integrated exhaust manifolds/turbocharger housings splits the exhaust channels from the cylinder head so the exhaust flows through separate scrolls based on the engine’s exhaust pulses. When matched with precise valve timing, that separation leverages exhaust-scavenging techniques to optimize gas flow, improves turbine efficiency and reduces turbo lag.

The electronically controlled wastegates — one per turbocharger — are used for more precise management of the engine’s boost pressure and subsequent torque response for smoother, more consistent performance. They are independently controlled on each cylinder bank to balance the turbo compressors’ output, for greater boost pressure response.

WATER-TO-AIR CHARGE COOLING AND DUAL THROTTLE BODIES

An efficient water-to-air charge-cooling system contributes to the engine’s performance, enhancing the turbochargers’ effectiveness. Similar in concept to an engine’s radiator, the system’s intercoolers cool the boosted air charge before it enters the cylinders. Cooler air is denser, which means there is more oxygen in a given volume, resulting in optimal combustion and more power.

The system features a pair of heat exchangers located above the valley-mounted exhaust manifold/turbocharger housings. The turbos pump pressurized air directly through the heat exchangers and into the cylinder heads. The heat exchangers are cooled by their own coolant circuit.

The intercoolers lower the air charge temperature by more than 130 degrees F (74 C), packing the combustion chambers with cooler, denser air. Also, the system achieves more than 80 percent cooling efficiency with only about 1 psi (7 kPa) flow restriction at peak power, which contributes to fast torque production.

Before entering the combustion chambers, the cooled air charge flows through a pair of throttle bodies, one for each engine bank. Each electronically controlled throttle body has a 59mm diameter opening.
http://www.gminsidenews.com/forums/f...ged-v8-285810/
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Old 03-21-2018, 04:47 PM   #7  
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exciting stuff.
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Old 03-21-2018, 04:52 PM   #8  
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Gad, I hope the Caddy engine auto stop/start isn't a feature that finds its way into the C8.




Love the forged internals, though.
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Old 03-21-2018, 04:54 PM   #9  
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Not unexpected.
Cadillac is launching a shitload of new models in the next few years and needs new powertrains.
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Old 03-21-2018, 04:56 PM   #10  
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Quote:
Originally Posted by OnPoint View Post
Gad, I hope the Caddy engine auto stop/start isn't a feature that finds its way into the C8.
My 2018 Grand Cherokee has a button on the dash to disable it.
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Old 03-21-2018, 05:02 PM   #11  
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Originally Posted by sunsalem View Post
My 2018 Grand Cherokee has a button on the dash to disable it.
Which you have to press each start-up? Or can you press once and it's off until you turn it on?

The latter wouldn't be bad, although I suppose one could just get in the habit of turning the damn thing off on every start-up if that's what it took.

I've recently driven 3 makes with this device - Ford, BMW and Mini - and damn what a ridiculous pos. And the annoying operation was on brand new vehicles. Can't wait to see how annoying it'll get with the accumulation of miles.
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Old 03-21-2018, 05:06 PM   #12  
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96 mm bore spacing on the new mill.

The current LT may be the last of the classic "small block" Chevrolet engines.

Kinda interesting.
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Old 03-21-2018, 05:17 PM   #13  
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Tadge said he does not like stop start on a Corvette, and while he never said “never,” he did say the Corvette would be the last GM product to have it.

Let’s hope he gets his way and it never shows up on our Corvettes!
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Old 03-21-2018, 05:20 PM   #14  
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Quote:
Originally Posted by OnPoint View Post
I've recently driven 3 makes with this device - Ford, BMW and Mini - and damn what a ridiculous pos. And the annoying operation was on brand new vehicles.
Agreed x1000. I can't imagine having to live with stop-start on a daily basis, it was annoying enough that I'll go out of my way to not even so much as rent one again.

Last edited by RedLS6; 03-21-2018 at 05:21 PM.
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Old 03-21-2018, 05:26 PM   #15  
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Quote:
Originally Posted by elegant View Post
Tadge said he does not like stop start on a Corvette, and while he never said “never,” he did say the Corvette would be the last GM product to have it.

Let’s hope he gets his way and it never shows up on our Corvettes!
Amen, brother.


Quote:
Originally Posted by RedLS6 View Post
Agreed x1000. I can't imagine having to live with stop-start on a daily basis, it was annoying enough that I'll go out of my way to not even so much as rent one again.

I was really surprised with the lousy operation of it on the BMW - which was the worst of the three.


I look forward to seeing an exploded view of this new Caddy engine.
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Old 03-21-2018, 05:31 PM   #16  
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Default Actually! ;)

NASCAR: Camaro!

Le Mans: Corvette!

Cadillac GT ME: AWS, DOHC TT, Active Aero, Super Sports

Corvette Z51 ME: OHV, Fixed Wing, SS Cups


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Old 03-21-2018, 06:27 PM   #17  
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Heresy to say this (maybe) but if GM/Corvette wants to trim some weight how about a V6 version of this engine? Altho it's way back in Corvette's history, they did have 6 cyl. engines once upon a time. Plus, a twin-turbo version should be strong enough to power a lighter car, not a big Caddy.
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Old 03-21-2018, 08:51 PM   #18  
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Bowling green is said to build 3000 twin turbo v8s

How many can go to corvettes?

http://www.autonews.com/article/2018...autonews-daily
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Old 03-21-2018, 09:29 PM   #19  
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Quote:
Originally Posted by OnPoint
Which you have to press each start-up? Or can you press once and it's off until you turn it on?

The latter wouldn't be bad, although I suppose one could just get in the habit of turning the damn thing off on every start-up if that's what it took.

I've recently driven 3 makes with this device - Ford, BMW and Mini - and damn what a ridiculous pos. And the annoying operation was on brand new vehicles. Can't wait to see how annoying it'll get with the accumulation of miles.
On BMW you hit it once. Not each time you start the car. Had it been each start we would not have bought it. Im sure many feel the same way.
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Old 03-21-2018, 09:35 PM   #20  
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Johnny Lieberman from Motor Trend and a few published reports stated that the 4.2L DOHC TT V8 for this new CT6 model is brand exclusive, or that it was designed by Cadillac and will not be used by any other GM brand.

Last edited by Quinten33; 03-21-2018 at 09:37 PM.
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