Article Comments - 2009 Chevrolet Corvette ZR1

43 messages, Last post on Nov 02, 2009 at 12:18 PM

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What is this discussion about? Chevrolet Corvette, Coupe, Convertible

First Look: 2009 Chevrolet Corvette ZR1 - By now you probably have noticed that the ZR1 looks like, well, a C6 Corvette. The silhouette is, of course, the same and the overall dimensions are essentially identical to a Z06. (more)

2009 Chevrolet Corvette ZR1 V8: A Statement of Power - GM isn't just kidding around with the supercharged 620-horsepower V8 that's at the heart of the 2009 Chevrolet Corvette ZR1. (more)

First Drive: 2009 Chevrolet Corvette ZR1 - This ZR1 produces 638 hp — the equivalent of the power produced by the 405-hp 1995 Corvette ZR-1 (the "King of the Hill Corvette") plus a 1984 Corvette plus a 1968 Citroën 2CV. (more)

2009 Chevrolet Corvette Follow-Up Test and Video - Bottom Line: Beyond its amazing performance numbers, the Vette is a good value and offers surprising cargo space. It just takes some getting used to. (more)

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#11 of 43 Re: LS7 at its limits? [pmc4] by fedlawman Jan 01, 2008 (1:29 pm)
Replying to: pmc4 (Dec 31, 2007 9:35 pm) Your pasted charts are quite deceptive because of the scale. The revs on the Mercedes chart are crunched close together, making the power and torque curves appear steeper and the Corvette curves appear flatter. Pull out the numbers (and convert Kw/Nm to HP/TQ) however, and you see the real picture. Here are the approximate numbers (it is hard to read the M-B chart because of the size) pulled from your charts (I averaged the three Corvette runs): --------------------Vette (HP/TQ)-----M-B (HP/TQ) 3500 RPM _____260/400_______302/442 4000 RPM _____320/420_______348/457 4500 RPM _____380/440_______389/457 5000 RPM _____420/450_______442/457 _______________________________/465 5500 RPM _____460/440_______483/457 6000 RPM _____480/420_______496/435 ______________505 6500 RPM _____480/380_______503/420 ____________________________518 7000 RPM _____460/340_______496/370 The first thing you notice is that the Corvette engine never catches the M-B in power output at any RPM (it comes closest at about 4500 RPM). Dig a little deeper and the second thing you notice is that the M-B has the broader torque curve (more space below the curve). The Corvette reaches 90% of peak TQ (405 ft-lbs) at 3600 RPM and stays above 90% until 6200 RPM. The M-B reaches 90% peak of TQ at 2900 RPM and stays above 90% until 6200 RPM. In other words, the M-B is making 90% of peak TQ 700 RPM sooner than the Corvette. Both the Corvette and M-B reach and maintain 90% of peak HP through the same range (5300RPM - past 7000 RPM). So to summarize, the M-B makes more horsepower and torque than the Corvette at all RPMs, and the M-B has the flatter torque curve. And Mercedes does it with 0.7 fewer litres of displacement (that's a 10% smaller engine). I think you need to lay off the Chevrolet cool-aid. Replies to this message: pmc4 (Jan 01, 2008 9:46 pm) fedlawman (Jan 02, 2008 12:21 pm) pmc4 (Jan 02, 2008 9:36 pm) and 1 more...
#12 of 43 Re: LS7 at its limits? [fedlawman] by pmc4 Jan 01, 2008 (9:46 pm)
Replying to: fedlawman (Jan 01, 2008 1:29 pm) Since your complaint surrounds a bad M156 dyno, here's an LS7 dyno that's just as generalised, showing 2K to 8K RPM's: And as we can see, the torque curve of the LS7 is substantially broader (almost by far) than the M/B V8. 370 ft/lbs comes in at near-idle, or 1,800 RPM. 470 tops out at 4,800 RPM, and the return to 370 ft/lbs is at a far-reaching 7,000 RPM's. With this engine, 500 nm is at both 2,000 RPM and 7,000 RPM's with peak torque (630 nm) occuring in not one but two places: 4,200 and 5,000 RPM's. Since the LS7 is generating all that power even below 2,000 RPM that extends well beyond 7,000 RPM; and since the M156 doesn't really start generating power 'till 2K RPM with a very sharp drop-off at 7,000 RPM, it's easy to see why Motor Trend is saying the LSx engine is the best V8 engine in the world: The LS7, as I said earlier (you know, before you posted your misleading and deliberately inaccurate "data"), is just flatter, broader and more powerful than the M156 engine. "The first thing you notice is that the Corvette engine never catches the M-B in power output at any RPM (it comes closest at about 4500 RPM)." The Corvette engine does in fact generate more power than the Mercedes engine; your facts are from an earlier engine (early 2000's, perhaps? The LS6?), or from an entirely different manufacturer. Try again, just without the obvious misleading info. Replies to this message: fedlawman (Jan 02, 2008 12:21 pm) pmc4 (Jan 02, 2008 9:36 pm)
#13 of 43 Re: LS7 at its limits? [pmc4] by fedlawman Jan 02, 2008 (12:21 pm)
Replying to: pmc4 (Jan 01, 2008 9:46 pm) "here's an LS7 dyno that's just as generalised, showing 2K to 8K RPM's:" Another LS7 dyno?!?! Just how many are you going to need to try and make your point? "your facts are from an earlier engine (early 2000's, perhaps? The LS6?), or from an entirely different manufacturer. Try again, just without the obvious misleading info." Ummm, I used the charts YOU posted. And I'm sure you realize that any dyno charts that you can find for these cars are far from scientific. Tell me, what was the ambient temperature on the day these Corvette and Mercedes dyno runs were made? What was the relative humidity? Density altitude? Did they use a Dynojet or Mustang dyno? Replies to this message: pmc4 (Jan 02, 2008 9:36 pm)
#14 of 43 Re: LS7 at its limits? [fedlawman] by pmc4 Jan 02, 2008 (9:36 pm)
Replying to: fedlawman (Jan 02, 2008 12:21 pm) Tell me, what was the ambient temperature on the day these Corvette and Mercedes dyno runs were made? What was the relative humidity? Density altitude? Did they use a Dynojet or Mustang dyno? All dyno's measure an engine's output with the engine off the car (at least that's how the manufacturer measures engine output). The tested car that's connected to the dyno is having its RWHP measured, not engine output, thus your questions are mute since engine power and not RWHP is the statistic that's being measured. Anyway, the second graph I posted was more comprehensive, measuring power output below 2K and above 7K RPM. Just how many are you going to need to try and make your point? The point here is is that you did get the point; the point being is that the LS7 has a broader power output and greater torque than the Mercedes engine.
#15 of 43 So what are your thoughts by claires HOST Jan 02, 2008 (10:32 pm)
about the ZR1? Replies to this message: pmc4 (Jan 03, 2008 11:35 am)
#17 of 43 Re: So what are your thoughts [claires] by pmc4 Jan 03, 2008 (11:35 am)
Replying to: claires (Jan 02, 2008 10:32 pm) about the ZR1? Ummm, I dunno. If it were priced at or around $250,000, would it be worth it? Tough call, IMHO...