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08-26-2013, 04:29 PM | #176 |
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I do wish the first virtual gear was a little shorter in the cvt tho. It is the nicest CVT I've driven thus far, fwiw
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08-26-2013, 06:55 PM | #177 |
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08-26-2013, 07:13 PM | #178 |
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Some math whiz should kick out the various engine rpm at different speeds, such as 55mph, 65mph, 70mph, 75mph and 80mph so we can compare the CVT vs the 5 Speed.
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08-26-2013, 09:39 PM | #179 |
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08-26-2013, 09:54 PM | #180 | |||||
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Quote:
Quote:
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Here are some hints: The red line are cvt's, and to the right means better fuel economy. Think about it for awhile... Better yet, why don't you update the data (chortle) Quote:
You're hardly throwing strikes. Quote:
Well at least you can count to three. |
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08-26-2013, 10:32 PM | #181 |
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I'm sure glad a 6 month old graph keeps returning
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08-26-2013, 10:47 PM | #182 |
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08-26-2013, 10:59 PM | #183 |
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My hunch is he started to crunch the numbers, realized that the final drive and gear ratios ultimately show that in fact the CVT on the highway turns lower rpm than the 5 speed (which it certainly does), and then stopped looking at the numbers and started his argumentum ad hominem ad nauseum again...
Cause that is what he is left with, after avoiding inconvenient truths. |
08-26-2013, 11:03 PM | #184 | |
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Have you figured it out yet, or are you colorblind? Which transmission, delivering the best mpg's overall, represented by the red bar at 33mpg, is on your chart again? |
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08-26-2013, 11:36 PM | #185 |
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So, forgive me for "overlooking" this graph before. This graph has nothing of value on it. I see that of the drivers of the CVT listed, albeit no idea demographics of either whatsoever, have more of a spread in mpg. I see that 5MT low avg is better than CVT but again, no demographics on either. I see that the CVT gets better overall mpg on the high side, as the 5MT isn't even high enough to chart since it doesn't exceed its EPA estimates like a 5MT corolla might, but again no demographics. I see red and blue lines and that's about it. I couldn't make a business decision based off of this graph, and in my world that makes it nothing more than colors and numbers that mean very little.
Maybe there was a paragraph 6 months ago that qualified the graph that I missed as well. |
08-27-2013, 02:34 AM | #186 | |
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That's the problem with the CVT. The engine is too weak to maintain "high" gear. So what happens is when one gets to a small grade the vehicle slows, and since there is tolerance in the cruise control, it slows a couple of mph. Then a threshold level is passed and it "downshifts" to a high rpm to catch back up. That downshifting is horrible on mpg - one can watch the gauge if it's in instantaneous as it drops - sometimes it will drop to below 10 mpg. That really hurts overall mpg. Even on the flat, though, head winds can make it downshift since it's geared so high. If you drive 50 to 60 mph with no hills and no headwind it's okay - but that's not highway speed in a normal situation. And, locking it in 6th it won't even maintain speed either so that's out. So if you are back east on the flat with a slow speed limit it's not too bad, but trying to keep up with traffic on hills etc. it will downshift at the slightest grade, or maybe even not stay in "high" gear on the flat. On the back roads at 65 I can get 36 with a tailwind but typically it averages around 31 or 32. P.S. Here's the graph data: https://mega.co.nz/#!yxoXnRhA!CzdrBF...PWIcG4k-VA-ly0 |
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08-27-2013, 06:37 AM | #187 | |
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As expected, Stevenhnm is already dissembling...'cause, you know, pulling a trailer with a 5 speed would result in good mileage, etc...and he drives on hills (apparently he does not realize upstate NY is not Kansas)...
However, look at the math and...ding - ding - ding, we have a winner! Two calculations shown @ 70mph, tire size is that of a Sport Impreza. CVT clearly turns lower RPM at highway speeds, which accounts for the higher EPA Highway rating, that top bar in the Fuelly data, and the NASIOC CVT owners who report better highway mpg's than I have ever seen in my 5 Speed. The CVT is a little heavier than a comparable 5 Speed, so here's the science behind why a CVT gets better HWY mpg's than a 5 speed... RPM calculator used: http://ctny.audiworld.com/mark/s4/gears/gear_calc.html 5 Speed (5th gear): CVT (top gearing): Wanna see what happens in a 5 Speed if you have to downshift to 4th? (same reason a CVT drops gearing, for example, driving up a steep grade -- he must think I just power up those hills in 5th?): Ouch! He might want to rethink trading in his CVT and getting a 5 speed and expecting better mpg's... Quote:
Last edited by Zeeper; 08-27-2013 at 07:44 AM. Reason: 'cause math is a bitch when it don't agree with you |
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08-27-2013, 06:39 AM | #188 | |
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Last edited by Zeeper; 08-27-2013 at 07:45 AM. |
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08-27-2013, 08:17 AM | #189 | |
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What happens in the CVT in the same situation when it has to drop gearing to make it up the same steep grade? At that, redo the numbers at 65mph, 60mph and 55mph and you'll see that the CVT *has to* drop to "4th" (or lower) to make it up a steep grade. Any RPMs lower than around 1800rpms will lug and you'll lose speed/power trying to get up... necessitating a shift to a different gear/ratio. In a 5MT, you still have enough power/torque in the highest gear to still make it. Overall, I would bet that it takes more fuel for a CVT to make it up a grade when it has to shift to a "lower" gear vs the 5MT being able to make it up in 5th. --kC Last edited by KC; 08-27-2013 at 08:24 AM. |
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08-27-2013, 08:21 AM | #190 |
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Bring the arguing into the other mpg-trashing threads please...
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08-27-2013, 10:56 AM | #191 | |
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So your theory is wrong. |
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08-27-2013, 11:10 AM | #192 |
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CVTs have more drive-train power loss than a manual, it isn't all about RPMs.
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08-27-2013, 11:17 AM | #193 |
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08-27-2013, 02:12 PM | #194 | |
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Just last week I drove 84 from CT to 81 in PA through Scranton, Wilkes-Barre, etc... down to Mechanicsburg/Carlisle (and back). At highway speed, I never had to downshift out of 5th to make it up any of those hills, and that was at 55/65 mph (5 over the limit on cruise control). So, you can scream on the internet until you're blue in the face about this or that... but I'm just relating personal experience, which is 100% fact: I didn't have to downshift out of 5th in my 5MT to go up any hills at speeds greater than 50mpg, especially on that section of road you use for an example. And at that... 81 from Scranton/WB to Carlisle is the gnarliest section of 81. North of Scranton is just some hills and south of Carlisle relatively flattens out to Hagerstown MD. Under 2k rpms, going up a hill, either car will have to shift because it won't have adequate power to make it up a steepish incline. However, the CVT is under 2k rpms at 70mph in top gear. The 5MT in its top gear is turning 2k RPMs at 49mph. The 5MT has adequate power in 5th gear at highways speeds to make it up highway inclines at speed. And I can tell you this... the math is sound. With a 5MT carrying higher RPMs in 5th than top gear of the CVT, it means it also has more available power/torque due to those higher RPMs. Just look at those two 70mph charts you posted... the 5MT in 5th is carrying 2870ish RPMs and the CVT is a hair under 2000. --kC Last edited by KC; 08-27-2013 at 02:22 PM. |
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08-27-2013, 02:36 PM | #195 | |
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08-27-2013, 02:40 PM | #196 | |
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But I do drive from Albany to Bernardston, MA quite often, and you cannot drive that route (route 2 thru North Adams or 7 through southern Vermont) over the berkshires without downshifting into 4th (in fact, you have to downshift because the cruise control response is a bit laggy, so when you encounter a significant grade it reacts so slowly that if you don't downshift to maintain power, the car will stall). You are welcome to try it, but you will only prove yourself wrong. There are additional problems with your theory, including the following: The EPA test is not a constant speed test on the dynamometer. It is a test where the car goes through cycle of acceleration and deceleration. This means the CVT has ample opportunity to change gearing ("constant and variable") yet returns higher mpg's in that test. Also, the Fuelly data shows only CVT's returning the very highest mpg's So what is the evidence that the Continuous Variable Transmission always chooses the WORST possible gearing ratio in any circumstance (including driving uphill) while having a fixed ratio of the 5 Speed returns the BEST possible mpgs in the same type of driving? One might surmise that having the possibility of selecting variable gearing would return a better powerband than having to select between two fixed ratios -- but your solution to that is to say the 5 speed top gearing is optimal, and you never need 4th on the highway (so come drive the scenic berkshires and see for yourself). Also makes you wonder why some 5 speed owners wish for a 6th speed, with an even better ratio to optimize mpg's when not driving in the mountains... Additionally keep in mind that the CVT distributes relatively less power to the rear wheels most of the time (so less drivetrain drag) -- not sure why anyone believes it suffers from more drag, but do tell... Yours is just another theory, and one that I just pointed out has significant holes in it. It makes me wonder when you will start to believe the EPA testing, the Fuelly data, and the reports from CVT owners who are achieving higher than EPA mpg's, much higher than I have seen in my 5 Speed? Last edited by Zeeper; 08-27-2013 at 04:19 PM. |
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08-27-2013, 07:31 PM | #197 |
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My vette will downshift at the slightest hill no matter what. It has plenty of power, just geared for better mpg on hwy in OD, but its such a high gear.
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08-27-2013, 11:45 PM | #198 |
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I occasionally use M mode on my CVT for hilly work. I don't mind losing a little speed for hypermiling or can pick a gear when I know better than the transmission does. It's a pretty sweet transmission IMO.
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08-27-2013, 11:49 PM | #199 |
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Yep, definitely have to use manual mode on anything even slightly resembling an incline. It'll drop down to 5th (CVT) in a stiff breeze.
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08-28-2013, 08:11 AM | #200 | |
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2) I had assumed (bad on my part) that the final drive between the 5MT in the Impreza and 5MT in the XV was the same. They are NOT. Impreza *is* 4.111. XV? 4.444!! Why are they different? No idea, but I'm not complaining! However, that may be an explanation on why I can get up hills at highway speeds without issue... I'll have more RPMs at speed with my 4.444 (and marginally quicker accelleration off the line). 3) As stated in #1, and verified last night on the highway thinking about this thread, I came to realize that calculator is and has to be incorrect. This morning... putting in the correct values for my XV (which has 225/55-17s vs Impreza 205-50-17... taller tires in the XV), running at 70mph, 5th gear is the same at .780 and with the corrected FG of 4.444, the calculator is still about 100rpms on the low side (it's saying 3049). Driving to Boston last night, doing 70mph in 5th, I was running about 3200 rpms on flat level road. At 65, I'm just under 3k RPMs. Knowing this, and running at 55mph I'm still above 2k rpms in 5th. (Around 2400rpm to be exact) Ah hah! [Gru] Light-bulb! [/Gru] That there is the major reason why I didn't have to shift out of 5th on hilly highway... I have even more RPMs (than originally posted yesterday) in the XV than the Impreza with a 4.444 Final Drive vs 4.111 (and bringing it all around) why I can get better gas milage going up hills because I don't have to go to 4th. I'm telling you, I wasn't making it up. I don't have to go to 4th to get up hills at highway speeds! (And I feel bad that you do). So all that said... I'm going to bow out of this Impreza thread, and start a new "I love my XV MPG... and LOWER GEARING" thread. Sorry for any and all confusion and now bring you back to your originally scheduled programming. --kC |
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