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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.
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.
This makes one wonder if perhaps the mid engine car isn't the C8 but instead is a new Cadillac supercar.
CADILLAC HAS A NEW V8: MEET THE NORTHSTAR 2.0 (WITH 4.2 LITERS)
Two turbochargers and 550 hp will propel the upcoming Cadillac CT6 V-Sport
MARCH 21, 2018
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 5,700 rpm and tractor-pull-worthy 627 lb-ft of torque between 3,200 and 4,000 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 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 90-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 warmup to operating temperature. Fuel injection is direct into the cylinder, spraying at 5,076 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-2,000 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. But both will come with what Cadillac promises is that distinctive V8 character. And they’re probably right, but you’ll have to wait to the first half of 2019 to find out.
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.
Using refrigerant to cool intake charge not specifically stated but implied via utilization of 20kw charge air cooling system = reduction of emissions, improved fuel economy and increased power.
Seems as if the 10 speed torque converter automatic might make it into the corvette.
A little surprising.
Hard to imagine the corvette team will ignore this transmission is available from GM although a transaxle would be needed for the corvette so a dct possibility is not completely dead.
Guess we will find our for sure in about 8 months.
This makes one wonder if perhaps the mid engine car isn't the C8 but instead is a new Cadillac supercar.
Ah yes, this poor, beaten till death horse that keeps arising. Please note:
1) c7pimp told us explicitedly that the car has a Corvette emblem on its hood;
2) While other media has chosen to label the 4.2L DOHC, 32V, TT motor as exclusive to Cadillac, in the official Media.Cadillac press release today, Cadillac did not use that word.
And while it might have a part number (P/N) exclusive to Cadillac, that fact that it has a P/N that is unique to Cadillac could be nothing more than its top lid being stamped, “Cadillac.” The identical motor with a “Corvette” stamped top lid will also have its exclusive P/N — and it will live 100% within Corvette engine bays.
So we will have two “exclusive 4.2L, DOHC, 32 V, TT motors,” yet their identical internals of both will reside within two different GM brands.[/B]
The cost to develop such a new motor is astronomical, and so it will be, like many other GM major parts, such the A6, the A8, the 6.2L, etc., shared across appropriate and different GM products/brands.
Today’s announcement does nothing to dissuade that the 2020 ME will have the same, or to be totally accurate 99.9% the same, motor.
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!
elegant: Can you cite where/when Tadge wrote or said this? Not doubting your recollection here, but I'd like to have a direct reference to statements regarding this important issue.
While even Corvette chief engineer Tadge Juechter isn’t a fan of the idea because it’s “more mass and more cost,” the C7 Corvette program may eventually implement start/stop technology, if government mandates push hard enough.
“It is very disconcerting to have your lively, great-sounding engine stall every time you come to a stop. The real customer value, the real environmental value is zero. So you are hauling around all that stuff to get a better label value (for mpg on the window sticker). It wasn’t worth it,” he said in an Edmunds report that came from last week’s 2014 Corvette Stingray launch drive.
Sadly, Juechter continued with saying that “customers will have to put up with changes from what they traditionally expected in order to get better economy.”
Originally Posted by Edmunds.com: When Tadge was interviewed right after the C7 was revealed
MONTEREY, California — General Motors considered stop-start technology for the redesigned but opted against it, deciding it would hurt the car's image. But GM may be forced to make it standard later this decade.
"It is more mass and more cost," Tadge Juechter, Corvette chief engineer, told Edmunds. "It is very disconcerting to have your lively, great-sounding engine stall every time you come to a stop. The real customer value, the real environmental value is zero. So you are hauling around all that stuff to get a better label value (for mpg on the window sticker). It wasn't worth it."
Juechter was interviewed during a 2014 Corvette Stingray press event here.
The highway fuel economy for the 2014 Corvette Stingray has increased nearly 12 percent, compared with the 2013 model. Equipped with the standard 6.2-liter V8 and new seven-speed manual transmission, the new car is rated at 17 mpg city/29 mpg highway, according to the EPA.
In comparison, the 2013 Corvette with the 6.2-liter V8 and six-speed manual transmission is rated at 16 mpg city/ 26 mpg highway.
What General Motors might be required to do in several years to boost the Corvette Stingray's fuel economy has not been determined. Federal regulations mandate each automaker to increase the vehicle fuel economy of their fleet 4 percent annually through 2025.
Asked if it is inevitable that stop-start technology may be standard on a future Corvette Stingray, Juechter said "it may be.
****
I am not finding one last article in which Tadge said, that if he had anything to do with it, the Corvette would be the last GM model to have start stop tech.
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.
Sadly, it isn't the latter.
I have to remember to hit the button every time I fire it up (something that is hard to do when ya get old ).
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.
I'm sure the manufacturers came up with this tech as a way to show the Feds they are REALLY trying to be conscientious about increasing MPG.
Good job pulling all the sources to make a rather strong case the new engine is bound for the new ME Corvette.
I think; horsepower numbers at hand, this last bit invalidates my theory Corvette was going with two sport 2 seat platforms "ala Porsche" with the ME being "inferior" to the FE.
JerryVette (I believe) has a very good counterargument tid bid: 3000 engines a year enough for Caddies and Corvettes...?
Sadly, it isn't the latter.
I have to remember to hit the button every time I fire it up (something that is hard to do when ya get old ).
I'm sure the manufacturers came up with this tech as a way to show the Feds they are REALLY trying to be conscientious about increasing MPG.
This engine is multitudes relatively more efficient than the LT4 let alone the LT5! And adding boost (If possible with 170K RPM) would improve that for free. Power transisters and turbos are God's gift! And they look to be adding less mass, as well.
But
The C8/C8R only really needs the chassis frame right away!
Last edited by johnglenntwo; 03-22-2018 at 08:48 AM.
JerryVette (I believe) has a very good counterargument tid bid: 3000 engines a year enough for Caddies and Corvettes...?
Reading the Cadillac’s official press release, it does say 3,000 in quantity. It says nothing about Corvettes. So if hypothetically, there were 19,000, 32 V, DOHC, TT, V8’s going into the 2020 ME Corvette and an additional 3,000 of the 4.2L’s going into the Cadillac, Cadillac's press would be right (that is the only media source I know is correct), and there would still be plenty of motors for the Corvette.
Further while some of the documentation says the Engine is more compact than the small block V8, this does't take into account the exhaust piping.
If you removed an LT4 from a current Z06, this motor would physically fit, until you tried to run the exhaust and realized your only option would be to come off the front of the engine (or go over the sides) not out the back as required.
This engine could fit, if the hood were lengthened (or the height profile was changed). I'd still be concerned with heat dissipation though.
Interesting thing to note, a Hot-V design means there will not be a NA or supercharged version of this engine family, it will be exclusively turbocharged.
Sadly, it isn't the latter.
I have to remember to hit the button every time I fire it up (something that is hard to do when ya get old ).
I'm sure the manufacturers came up with this tech as a way to show the Feds they are REALLY trying to be conscientious about increasing MPG.
Start/Stop has to be "auto-enabled" to qualify for the MPG increase on the sticker.
There are ways to disable it, but most of them involve finding what the inhibits are and spoofing the CAN message (or changing another module to think that it doesn't have the feature and always request it be turned on).
And Engine tune will also be able to delete it, like DoD/AFM.
The CAD drawings clearly show two different engines.....
1) a NA engine that is not a Hot-V design with swept up tubular exhaust manifolds on the outside of the heads with the CATS mounted on the outside.
2) a TT engine that clearly is not a Hot-V design, as the turbo's are mounted low and outside of the block.
I'm of the opinion, Engine 1 got cancelled. That was supposed to be the NA Flat Plane Crank based on the 6.2L LT1 made DOHC. Doens't mean it got deleted from CAD.
Engine 2, is from this family. The heads could be differnet to not do a hot V (it's possible to support both). Why GM would do that? I'm not sure, it makes sense to keep the design as is.
I'm of the opinion, Engine 1 got cancelled. That was supposed to be the NA Flat Plane Crank based on the 6.2L LT1 made DOHC. Doens't mean it got deleted from CAD.
Engine 2, is from this family. The heads could be differnet to not do a hot V (it's possible to support both). Why GM would do that? I'm not sure, it makes sense to keep the design as is.
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.
If it does, it's because they had no choice. Not like the engineers WANT to do it...they do what's necessary to build the car to a level of performance. I think a lot of people lose sight of the fact engineers don't enjoy putting CAGS functions in and doing cylinder deactivation...it's a necessary compromise to build something beasty with all the regulation bs.
03-21-2018, 09:35 PM
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