03-11-2013, 05:53 AM | #491 | |
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03-11-2013, 07:47 AM | #492 |
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Small displacement turbocharged engine all depend on how you drive them. If you drive them like you stole them then you won't get any better fuel economy than their NA counterparts. Meanwhile there are a ton of Cruze ECO owners out there doing 45 MPG all day long.
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03-11-2013, 07:52 AM | #493 | |
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It's because under conditions where you aren't into boost that the smaller FI engine drops back into essentially NA mode that you make any fuel economy gains. So it makes sense to let the turbo engine stay out of boost during the emissions and mpg certification as much as possible. Whether that happens in any random driver's daily driving is a different matter, though I'd guess that you (as a mfr) wouldn't want the boost to be too far out of reach during normal driving lest the car get exactly the reputation that the V8 side is viewing 4 cylinders in general with (a bog-slow low-compression NA 4). An enthusiast will tend to keep the engine at an rpm where boost will be available very quickly, while a non-enthusiast will tolerate longer periods of no boost and sluggish acceleration. Then again, when a 4 cylinder turbo is fitted with a manual transmission, even a non-enthusiast will tend to keep the transmission in each lower gear longer when driving in traffic. I'm not going to chase down the data to argue overall cost of ownership other than to note (again?) that with an I4-T you have a simpler block casting, single exhaust with fewer catalytic converters and mufflers, and one less head with its valvetrain and associated controls. The financial advantage might still favor the V6-NA over the turbo-4, but it won't be by as much as the cost advantage that the V8-NA enjoys over the V6-TT, where the V6 here still has the V block casting, a more extensive intake, the same amount of exhaust plumbing, and the same number of heads, etc. Norm Last edited by Norm Peterson; 03-11-2013 at 08:56 AM. |
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03-11-2013, 08:41 AM | #494 | ||
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03-11-2013, 08:57 AM | #495 |
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I think it's got something to do with catalytic converter durability.
Ford does the same thing, and aftermarket tunes are somewhat leaner. On edit, I think we ought to assume DI for all of these engines. Norm |
03-11-2013, 10:21 AM | #496 |
I used to be Dragoneye...
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That's fair - I didn't remember seeing that...but I haven't been following the Vette as closely as I follow the Camaro...
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03-11-2013, 11:34 AM | #497 |
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Am enjoying all you boys' expertise..."Real world" mileage I'd say is a non-issue...I don't think anybody really expects to get what is advertised...The "rated" mileage on the window sticker is what will rule the day, and determine what is offered for sale...
...Also, I'm just not seeing where a V-6 would fit into all this...I think Norm said earlier that the total year numbers for the Camaro would make GM hard-pressed to sell three different engines...as well as a ttv6 being more expensive and not as efficient as the v-8.???.....Things are getting as clear as mud!...lol... Please carry on, and thanks.... |
03-11-2013, 11:53 AM | #498 | |
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It's probably more a "gut-feeling" and quick mental math month-to-month...lol... |
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03-11-2013, 12:16 PM | #499 |
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Based on my 2.0T, mpg is directly based on driving habits. Under normal driving with a 45mph speed limit, using 3-5 lbs boost I can get 22mpg. On the highway driving like a normal person at 70mph I can get 30mpg. On the flip side of that, if I were to get into the boost at 20-23 lbs my mpg drops to around 14. The 2.0T has the GMPP tune, putting out around 300hp / 350TQ. Even with the higher numbers from the tune, the mpg has remained the same, but now requires 93 octane.
With the ZL1 it's rated at 12/19, and driving normal and staying out of the boost, around town I can get 13 mpg and 20 mpg highway. On the flip side of that, if I get into the boost and drive stupid the mpg will drop to 7 or 8.
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03-11-2013, 02:25 PM | #500 | ||||
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And some of these engines are getting small to the point that you don't necessarily have to be demanding that much power to make spooling up the turbos necessary. All it may take is a small hill with the cruise set. Quote:
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03-11-2013, 02:45 PM | #501 | |
I used to be Dragoneye...
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Technically, they're already selling 4 different engines...and if this LS7 rumor turns out to be true: 5 engines... If the powertrain options we're talking about are shared with the ATS, then a good chunk of the powertrain development for "extra engines" is essentially free... |
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03-11-2013, 02:58 PM | #502 | |
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Last edited by 90503; 03-11-2013 at 03:26 PM. |
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03-11-2013, 05:30 PM | #503 | ||
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Norm |
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03-11-2013, 05:38 PM | #504 | |
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But, again, what GM has done with the Impala may or may not to be relevant to what will happen to the Camaro. Maybe GM thinks Impala buyers are more comfort-oriented, i.e., they want a big, cushy car but are not so concerned with having a hot engine, so they won't notice or care that the new engine is a slug. I do know, though, that a typical Camaro buyer WILL notice. |
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