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Thread: New Corvette engine unveiled: the fifth generation of Chevy small block is here

  1. #11
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    Quote Originally Posted by cvjoint View Post
    Cylinder deactivation on the other hand just adds bulk and complexity and offers nothing performance wise.
    Do you have any data to show what the hwy fuel economy is with and without cylinder deactivation? if 27+ on the freeway i the vette, can we assume that is on 4 cylinders, not 8? what would it be on 8?

    Why assume there's nothing performance wise?

  2. #12
    Senior Member cvjoint's Avatar
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    Quote Originally Posted by Whiterabbit View Post
    Do you have any data to show what the hwy fuel economy is with and without cylinder deactivation? if 27+ on the freeway i the vette, can we assume that is on 4 cylinders, not 8? what would it be on 8?

    Why assume there's nothing performance wise?
    Only GM has this data since the car is not yet released. Early summer the magazines will get the car for testing. It is said to have multiple driving modes, eco and so on. If one of those does not drop in 4 cyl than it can be quickly done. The power-terrain chief said the hwy mpg will surprise people, and that the engine has the best BSFC output on the market when running in 4 cyl mode.

    Cylinder deactivation does not add anything in terms of performance. The torque tube was replaced with a heavier steel one to dampen the extra vibration in 4 cyl mode. The exhaust manifold has extra butterflies to dampen the noise in V4 as well. The lifters in the engine will also add weight and complexity.
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  3. #13
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    Performance can be measured in terms of more than power.

  4. #14
    Senior Member cvjoint's Avatar
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    You can change the common definition of performance to mean anything you want, even making eggs.
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  5. #15
    Senior Member cvjoint's Avatar
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    I look at performance as being separate from fuel efficiency because frankly I would never trade off go fast ability for fuel efficiency.
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  6. #16
    Founding Member n_olympios's Avatar
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    You might not, but global economy and (mainly) marketing say otherwise.
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    Virtus probata florescit: reversio

  7. #17
    Senior Member cvjoint's Avatar
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    Tadge Juechter @ GM said the Corvette implements fuel economy technology in order to improve fuel efficiency for the GM lineup as a whole. With the ever increasing Corporate Average Fuel Economy standards some hard choices had to be made. Tadge is not the kinda guy to trade off performance but to keep the Corvette alive this was a worthy tradeoff. Corvette could sell 30k units in a given year and that will impact the fuel economy of the fleet as a whole.

    From snooping around I gather this will be the last V8 Corvette we will see. I definitely plan on snatching one for myself before the engine gets downsized. The likely candidate for the future is the smaller brother 4.3L V6 push-rod + turbines. I would much rather get the 6.2L V8 and feed it with the large C38-92 Rotrex blower.

    CAFE is going to fast imo. Technological breakthroughs are what we want to drastically reduce fuel consumption, not a painful reduction in power output. The auto industry does not have the new breed of combustion technology, what we see is downsizing to 4 cyl (+ turbo) across the board.
    Last edited by cvjoint; 01-14-2013 at 03:20 PM.
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  8. #18
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    I gotta agree with the cylinder deactivation being un-needed. They are claiming 27mpg+ freeway. The previous V8 did 26+ freeway with the manual trans. Drive it reasonably on the freeway and you could top 30 mpg. The car has always had a very tall overdrive, and its had relatively good aero for a long time as well, both the things needed for good freeway mileage. The vette is the only car out there in its performance range that avoids the gas guzzler tax here in CA. I would almost say that something went backwards efficiency-wise (be it the engine or car itself, aero) if the car now needs cylinder deactivation to get to 27mpg freeway.

    Now, if 27mpg is with all cylinders active, and then it gets better with 4 cylinders shut off, then I can see benefits (from a regulations standpoint).

  9. #19
    Senior Member cvjoint's Avatar
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    They won't say what the MPG is yet until EPA rates it. could be 27 or could be 30. The first six gears are equally long as the old ones, but the new 7th gear is even longer. They are leveraging the extra torque down low from VVT and DI to get an even lower cruising RPM and stay in the 4 cyl mode longer. It would be cool if they had a 4 cyl only mode to see what it can do.

    Car audio wise I think this car is spectacular. I listened to Craig's 'vette lots and the setup is very good. Lots of cabin gain, lots of storage, and fuel efficiency wise the massive torque could mean it's one of the best cars in this department carrying around audio bulk. Most audio weight would end up over the rear axle so traction would improve a lttle to make up for the loss in power to weight ratio. Doors will probably house 10s again, and a cubby for the mids is viewable at the top of the door. 10 speaker stock sound system means a good starting point.
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  10. #20
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    Quote Originally Posted by TOOSTUBBORN2FAIL View Post
    I gotta agree with the cylinder deactivation being un-needed. They are claiming 27mpg+ freeway. The previous V8 did 26+ freeway with the manual trans. Drive it reasonably on the freeway and you could top 30 mpg. The car has always had a very tall overdrive, and its had relatively good aero for a long time as well, both the things needed for good freeway mileage. The vette is the only car out there in its performance range that avoids the gas guzzler tax here in CA. I would almost say that something went backwards efficiency-wise (be it the engine or car itself, aero) if the car now needs cylinder deactivation to get to 27mpg freeway.

    Now, if 27mpg is with all cylinders active, and then it gets better with 4 cylinders shut off, then I can see benefits (from a regulations standpoint).
    I dont care about regulations. It'll never make it under regulations if the car has to be under acceleration. all 8 will always kick in. But if shutting off cylinders produces a real improvement in hwy mileage then I am all for it. Especially if it gives us a de-facto FI type performance boost while allowing for improved mileage. But you are right, if the mileage is just 2mph higher, they need to do better. But that's no reason to give up on the technology.

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