05-03-2009, 01:20 AM | #1 |
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Top gear MPH?
Hey guys, I just got the the new C&D mag and it had another good review of the Genesis coupe and the LT Camaro with pretty much the same outcome as the Motortrend comparo. The Camaro won by 1 point despite being a tad slower (0.4 to 60, but only 0.3 in the quarter). The transmission and ride were much better than the gen's, but what really got my attention was the top gear MPH speeds. The gen was 8.2 from 30-50, while the camaro was 15.8 and the gen was 7.6 from 50-70, while the camaro was only 14.3. Whats up with these times given they are both 6 speeds? I wonder if they chevy has a taller final gear ratio and maybe that's why it gets better highway mileage too?
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05-03-2009, 03:19 AM | #2 |
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I have no idea why they even do the "top gear" acceleration tests. They are stupid and don't show anything other than make some cars look slow and others fast.
and, btw, the Camaro lost on the latest test to the Hyundai. http://www.motortrend.com/roadtests/...ack/index.html |
05-03-2009, 07:38 AM | #3 |
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Genesis vs. Camaro @ 30 MPH:
MT in O.D. @ 1379 vs. 890 RPM and for reference: AT in O.D. @ 1264 vs. 796 RPM Genesis vs. Camaro @ 50 MPH: MT in O.D. @ 2298 vs. 1483 RPM and for reference: AT in O.D. @ 2107 vs. 1372 RPM Plus the Gen engine is 0.2 L larger, it could have slightly more torque. I'm sure this gearing difference has A LOT to do with the Camaro's better MPG !! I'll agree that this is a stupid test ... if I was rolling along at 30 OR even 50 MPH and wanted to get around someting quickly, I'd be downshifting. Hell, an automatic would not even be in O.D. until probably 1500 RPM. My 3.9L in my current Mustang will let me get down to 1000 RPM in O.D., but I'd never try to do more than just cruise along in traffic at this low RPM. If you want to see how all the gear ratios compare between the Genesis & Camaro, check out my Excell Spredsheet I did a while back 40 different cars in all including 8 2010 Camaro & 6 2010 Genesis Coupe variations ... http://www.camaro5.com/forums/showth...ht=Spreadsheet Doug |
05-05-2009, 09:58 AM | #4 | |
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On the original question, it has to be gearing. I assume the Camaro has an overdrive 6th gear to help highway mileage and the Genesis has a close ratio gearbox with no overdrive. I wouldn't worry about it. If you were trying for performance, you wouldn't have to upshift to 6th gear until about 120 or higher mph probably. My old mustang GT with a T45 transmission was the same way. It romped through 4th gear up to about 110-115 mph and then when you upshifted to 5th gear it felt like I threw an anchor out the window. |
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05-05-2009, 10:21 AM | #5 | |
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Quote:
Here are all the comparison numbers, right from my spreadsheet ... Differential: Camaro V6 ... 3.270:1 (all) vs. Genesis V6 ... 3.538 w/ MT & 3.727 w/ AT 6th Gear / Overdrive: Camaro V6 ... 0.750:1 MT / 0.670:1 AT vs. Genesis V6 ... 0.794:1 MT / 0.690:1 AT Tire Diameter / Revs per mile: Camaro V6 ... 28.646" Dia. / 726 rotations per mile (std. 19" 2LT, opt. 1LT) vs. Genesis V6 ... 26.716" Dia. / 779 rotations per mile (std. 19" Track model) All these variables make a difference in cruising RPM's. Go check out / download my Excel gearing comparison spreadsheet. You can actually change tire dimensions & gear ratios to see how it changes MPH & RPM !! Doug |
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05-05-2009, 06:40 PM | #6 |
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I tried to search for this but it is confusing. So, I take it if you have a higher gear ratio, the car will be faster, but get worse mileage correct?
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05-05-2009, 07:03 PM | #7 | |
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Wait, so they test acceleration in high gear to make a properly-geared car look bad? I guess this is why my VW buzzes along at 3000rpm on the highway when it could get another 10mpg if it had a properly tall gear and used its torque to do 70mph at 1800rpm.
Mrbobcat, the ratio for 6th gear doesn't matter for acceleration, any time you're in a hurry you won't be using 6th. 6th gear is for cruising at a steady speed on the highway (or if you're me and enjoy low RPM, it's for cruising at almost any speed). The Camaro has enough torque to pass uphill on the highway in 6th but if you're looking for excitement you should downshift (or with an automatic, you should step on the gas and let it downshift).
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Removing weight has surprisingly little effect on fuel economy
Engine break-in procedure | Gear ratios 2002 GMC Sierra 4x4 5.3 (190,000 miles and going strong) 1980 Buick Lesabre family heirloom with 36,000 miles 2008 Volkswagen Rabbit 2 door I5-2.5 5spd DD lease Quote:
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05-06-2009, 05:33 PM | #8 |
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I understand that the 6th gear ratio doesn't affect acceleration much unless your going for top speed. I was just curious why the times were that much different. I guess its good that it has a lower ratio in 6th which can only help mileage and if you want a quicker passing time you can just downshift a gear or two. Its just that the times of the top gear make the car look slower than it is. I bet the auto times would be much improved as it would automatically downshift when passing, but then I guess it would'nt be considered top gear acceleration then...
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05-10-2009, 10:01 PM | #9 | |
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Quote:
266 v 273
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05-11-2009, 03:38 AM | #10 |
Drives: 2011 V6 MCA & 1969 GT Mustang Join Date: Mar 2009
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I see that you are right ... but actually not much of a difference, however the Gen hits it's max torque at a lower RPM (4700 vs. 5200) and this could be more of a factor too.
Anyone seen HP & Torque CURVES for the V6 Camaro yet ?? There are dyno run results for both Genesis models (3.8 & 2.0T) in stock condition, but I've yet to see them for the V6 Camaro. Doug |
05-11-2009, 08:35 AM | #11 | ||
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Quote:
__________________
Removing weight has surprisingly little effect on fuel economy
Engine break-in procedure | Gear ratios 2002 GMC Sierra 4x4 5.3 (190,000 miles and going strong) 1980 Buick Lesabre family heirloom with 36,000 miles 2008 Volkswagen Rabbit 2 door I5-2.5 5spd DD lease Quote:
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05-11-2009, 03:06 PM | #12 |
Drives: 2011 V6 MCA & 1969 GT Mustang Join Date: Mar 2009
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Thanks holycow,
Flat is good ... now I know for sure I'll be able to dog the MT 6th gear down to 1000 RPM (~34 MPH) or so when rolling along with traffic like I've done the past 15 years in V6 Mustangs !! Doug |
05-11-2009, 03:24 PM | #13 | |
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You could even skip-shift 1st to 6th. What's redline for the 3.6? 1st gets you up to 35mph by 6000 RPM.
I mean, not that you would want to, but you could.
__________________
Removing weight has surprisingly little effect on fuel economy
Engine break-in procedure | Gear ratios 2002 GMC Sierra 4x4 5.3 (190,000 miles and going strong) 1980 Buick Lesabre family heirloom with 36,000 miles 2008 Volkswagen Rabbit 2 door I5-2.5 5spd DD lease Quote:
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05-11-2009, 04:37 PM | #14 |
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is using the tap shift excessively for this type thing bad for it? haha, i could see some great city gas mileage.
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