Yesterday, after a pleasant 9 innings at Goodwin Field watching Cal State Fullerton generally clobber UC Santa Barbara, our long-term 2009 Dodge Challenger and I found ourselves on wide open freeway. The first time I stepped out to pass in our Challenger, I realized I'd never before driven the car in light traffic.
I realized this, because I made a beginner's mistake: I left the Tremec TR-6060 six-speed manual gearbox in 6th gear -- and then had no torque with which to complete the pass. A blip of throttle and a hasty downshift to 5th ensued.
This gearbox has two overdrive gears -- a 0.74 5th and a 0.50 6th -- along with a 3.73 final drive. In practice, the engine is turning at all of 1,500 rpm at 65 mph when you're in 6th gear. Had I bothered to look at the tach first, of course, I never would have thought I could leave it in 6th. If you remember from our Challenger's trip to the dyno, the 5.7-liter V8 doesn't get into the meat of its torque band until you're past 2,000 rpm, but then it has plenty -- 350 pound-feet at the wheels.
It's not a big deal once you acclimmate (ask any Corvette owner, I'd imagine). But that first (and only) time you come up short for a pass, you feel like any weakling four-cylinder econobox driver. The difference is, in the Dodge, you can do something about it.
Erin Riches, Senior Editor @ 4,424 miles
carguy622 says:
11:50 AM, 05/ 4/09
I prefer a higher overdrive gear. It seems that more cars are gearing their top gears shorter, so you don't have to downshift, but the engine is spinning at almost 3,000 rpm in my TSX and Miata at 65.
sabre52270 says:
01:14 PM, 05/ 4/09
Ok, so I don't drive a stick, but want to learn. With that said, why would Erin have to downshift to 5 to pass? To get more torque from a lower gear? Would you then shift back to 6th once you passed? Why wouldn't you just leave it in 5?
eriches says:
01:35 PM, 05/ 4/09
@sabre52270: A very basic answer is that in a lower gear (5th gear, in this case), the engine is at higher rpm for any given speed. At this higher rpm, it's making more torque, which is what I need to accelerate past a slower car in front of me. (Of course, once rpm get high enough, torque will eventually taper off -- look at the dyno chart in the post I linked to see what I mean. But in 5th gear, this won't be an issue at normal hwy speeds.)
After I complete my pass, I do go back to 6th. It would be fine to leave it in 5th, but cruising in 6th at a lower rpm, is better for fuel economy. --Erin
sabre52270 says:
02:10 PM, 05/ 4/09
Ahhh. I see. Thank you for the quick explanation. It helps. I now have more questions, but they don't belong in this thread.
Thank you for your post and follow up.
ace47 says:
02:12 AM, 05/ 5/09
Whats the use of having a big displacement V8 when a turbo engine like the 1 series six cylinder makes better torque at lower rpms?
There is no use.
carguy622 says:
06:22 AM, 05/ 5/09
ace47: So you can say its got a HEMI! ;)
fadetoblackii says:
07:23 AM, 05/ 5/09
ace:
Off the top of my head it's probably because the turbo engine has no real benefit over the v8 other than slightly more torque at lower RPM's. It doesn't get better gas mileage, it doesn't make more power, and it probably won't last as long due to the higher stress a turbo puts on a motor.
ace47 says:
03:55 AM, 05/ 6/09
"ace47: So you can say its got a HEMI! ;)"
Can't deny that. Everyone likes bragging about their engine.
fadetoblackii- you have a point but my point is this. High displacement engines are known for their responsiveness at lower revs. If a turbo motor makes better torque at better revs, whats the use of a big displacement V8?
And Iam pretty sure the 1 series gets better mileage than the Dodge. The same inline six has revealed enough power to beat a Gallardo( u-tube video, Vishnu's). A turbo charged engine also has stronger internals and while turbo motors to fail, majority can last as long if not longer than NA motors with proper servicing.