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Can GM make Cadillac the standard of the world Again?

6098 messages,  Last post on Aug 14, 2009 at 4:43 PM

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What is this discussion about? Cadillac Escalade, Cadillac XLR, Cadillac STS, Automotive News


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#3455 of 6098
Re: First Drive: 2008 Cadillac CTS [plekto] by bumpy
Jul 29, 2007 (5:33 pm)
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Replying to: plekto (Jul 29, 2007 9:21 am)

EDIT: The new DI - look at that - diesel flat torque.
 
That's an artifact of the inflated torque scale on the chart. 700 foot-pounds? Come on, it's not a diesel. It's running 220 ft-lb at 1200 rpm (80% of peak), which isn't anything to get excited about these days. And what's with the VTEC-looking dip in the low 3000s?
 
This is what a flat torque curve looks like.
 
11.3 is pretty low compression for direct injection. 12 is about as low as any self-respecting engine builder should go.
#3456 of 6098
Re: First Drive: 2008 Cadillac CTS [fintail] by bumpy
Jul 29, 2007 (5:35 pm)
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Replying to: fintail (Jul 29, 2007 2:31 pm)

I am going to Vegas in a couple weeks, I see you can rent CTS there.
 
Rent a CTS-V and see how it compares to the E55.
#3457 of 6098
Re: First Drive: 2008 Cadillac CTS [bumpy] by fintail
Jul 29, 2007 (6:42 pm)
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Replying to: bumpy (Jul 29, 2007 5:35 pm)

I haven't seen those offered by any major firm, just plain CTS. I forget what the rate was, but under $100. I will probably get a S80/M35/A6 from Hertz, as I can get a discount.
 
I can get a S550 for $325/day from Dollar...but that's not gonna happen.
#3458 of 6098
Re: First Drive: 2008 Cadillac CTS [bumpy] by sls002
Jul 30, 2007 (3:59 pm)
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Replying to: bumpy (Jul 29, 2007 5:33 pm)

There are two peaks in the torque curve, which may mean a variable length intake manifold.
#3459 of 6098
Re: First Drive: 2008 Cadillac CTS [bumpy] by plekto
Jul 30, 2007 (8:43 pm)
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Replying to: bumpy (Jul 29, 2007 5:33 pm)

Compared to the imports, that IS a flat torque graph.
 
What's really important, though, is the under 3000rpm range where 90% of daily driving happens. An engine that's only putting out ~100-120HP at 3000rpm(and mile-tall gearing of course) is essentially no different than a little 4 cylinder turbo of old.
 
As for the compression ratio, yes, it's low. That's to be able to use standard gasoline. Or would you rather premium only?
#3460 of 6098
TQ curves Re: First Drive: 2008 Cadillac CTS [plekto] by rayainsw
Jul 31, 2007 (3:03 am)
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Replying to: plekto (Jul 30, 2007 8:43 pm)

“Compared to the imports, that IS a flat torque graph.”
 
There are exceptions to that sweeping generalization.
The current BMW 335i(xi) and 535i(xi) are prime examples.
At the flywheel, the torque curve of the 3.0L Twin Turbo motor is dead flat from approx. 1,500 to 5,000 RPM.
 
One ‘real world’ chassis dyno test:
 
http://www.automobilemag.com/features/news/0609_c_bmw_335i_dyno.jpg
 
http://www.automobilemag.com/features/news/0609_2007_bmw_335i_dyno_revised/
#3461 of 6098
Re: First Drive: 2008 Cadillac CTS [plekto] by bumpy
Jul 31, 2007 (6:19 am)
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Replying to: plekto (Jul 30, 2007 8:43 pm)

Compared to the imports, that IS a flat torque graph.
 
Not really. There's a dyno chart floating around for the G37, showing its torque curve to be almost literally flat from 2200 rpm to 7200 rpm.
 
What's really important, though, is the under 3000rpm range where 90% of daily driving happens.
 
Anyone who buys a "sport" sedan with the optional high-output engine, then loafs it along at 2000 rpm all day long has wasted their money. They should have bought a Buick or an Avalon.
 
As for the compression ratio, yes, it's low. That's to be able to use standard gasoline. Or would you rather premium only?
 
Yes. A premium car with a premium engine should be designed to run on something better than dishwater. Computer controls can retard the timing and fuel maps to allow cars to run on crap gas, so there's no good reason to hobble the engine with low compression. Anyone making the payments on a $40,000 car should be able to afford an extra 20-30 cents a gallon.
#3462 of 6098
Re: First Drive: 2008 Cadillac CTS [bumpy] by rayainsw
Jul 31, 2007 (6:29 am)
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Replying to: bumpy (Jul 31, 2007 6:19 am)

" There's a dyno chart floating around for the G37, showing its torque curve to be almost literally flat from 2200 rpm to 7200 rpm. "
 
This one???
 
http://www.automobilemag.com/features/news/0705_c+2008_infiniti_g37+dyno_chart.j- pg
#3463 of 6098
Re: First Drive: 2008 Cadillac CTS [rayainsw] by bumpy
Jul 31, 2007 (6:55 am)
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Replying to: rayainsw (Jul 31, 2007 6:29 am)

That looks like it.
#3464 of 6098
Re: First Drive: 2008 Cadillac CTS [bumpy] by plekto
Jul 31, 2007 (9:02 am)
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Replying to: bumpy (Jul 31, 2007 6:55 am)

There's a huge difference, though, between 2200-2400rpm and 1200-1600rpm in actual use.
 
Remember, despite it having all the power in the world, unless you can get a 6 speed manual gearbox with tight gearing in that "sports sedan" and then keep it in second gear around town(to get it into the 2500-4000rpm range - expect 16-18mpg!), you're stuck with loafing around town.
(of course *I* ignore gas mileage and do this - get about 250 miles per tank. 90% of people don't)
 
Mash the pedal - 3-4 seconds - 35-40 mph... torque converter locks up and you... "loaf". It shifts up a gear... you loaf. You want to unlock that torque converter and pass someone? Well, it's "loafing" at a whopping 900-1200rpm and you suffer a 2-3 second lag before it gets into its power band. The GM? Nope - none of that WOT-lag beahvior with this.
 
The BMW is an exception obviously because they use I-6 engines, which develop better torque and power for their displacement.(technically, the I-6 is the closest thing to a perfect engine that's possible from a power, weight, and efficiency standpoint - which is why BMW refuses to change)
 
P.S.
Though, you'll note that only TWO of the GM 3.6 applications are geared for low-end torque. The rest are no different from the standard stuff out there.
 
Go drive a CTS with the 3.6. Now, go across the street to the Buick dealer and drive the LaCrosse CXS. Same engine, same suspension, but which one drives better? Surprizing, isn't it? The CTS feels average. The CXS feels like a small block V8 from the 60s. Blip the throttle even a tiny but over idle and presto - maximum torque.
 
The new DI CTS seems to be simmilar - just without sacrificing HP to do it.

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