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Automotive News & Views Can GM make Cadillac the standard of the world Again?
6098 messages, Last post on Aug 14, 2009 at 4:43 PM
You are in the Automotive News & Views Forum. Your Hosts are steve_ & claires
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Replying to: bumpy (Jul 29, 2007 5:33 pm) 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?
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Replying to: plekto (Jul 30, 2007 8:43 pm) 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/ |
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Replying to: plekto (Jul 30, 2007 8:43 pm) 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.
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Replying to: bumpy (Jul 31, 2007 6:19 am) This one??? http://www.automobilemag.com/features/news/0705_c+2008_infiniti_g37+dyno_chart.j- pg
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Replying to: rayainsw (Jul 31, 2007 6:29 am)
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Replying to: bumpy (Jul 31, 2007 6:55 am) 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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Replying to: plekto (Jul 31, 2007 9:02 am) Who would want to drive at 1200-1600 rpm? As for the rest of it, it sounds like a torque converter is a death sentence for a good engine and a good reason to avoid the slushbox. Now, where's that manual Lacrosse? |
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Replying to: bumpy (Jul 31, 2007 9:34 am) |
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Replying to: bumpy (Jul 31, 2007 9:34 am) Me, for 1. My Corvette, in sixth gear shows 1600 RPM at approx. 73 MPH. A cruising speed I often find comfortable. Returning 30+ MPG. 80 MPH is approx. 1750 RPM. But who’s counting . . . - Ray Happy at low RPM, cruising & happy at high RPM accelerating ( um ) briskly . . .
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Replying to: rayainsw (Jul 31, 2007 10:04 am) But who would want to run a DOHC V6 that slowly? That's like asking a thoroughbred to do a mule's job.
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