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Author Topic: MPG doubled on manual over automatic???  (Read 3445 times)
ilyafish
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« on: June 21, 2009, 03:09:55 PM »

So I have been browsing around and seeing what is on the market right now, and alot of guys with coaches that have a manual transmission are claming they get roughly 10-11 mpg on a coach that gets roughly 5-6 mpg with an automatic.  I know if you drive it right, it makes a difference....but I have a hard time believing that it nearly doubles the fuel mileage.  If that is the case, I am in the market for a manual.  Just wanted everyones professional opinion as i originally thought this was a sales pitch but I see the same numbers coming up from different people selling their coach.

Also....if i find a coach i love but it is an automatic....what is the overhaul process we are talking about to make it a manual (and is it even worth it?)
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« Reply #1 on: June 21, 2009, 03:17:30 PM »

Hi Ilya,

I think the airplanes outside your hotel are stirring up pixy dust from Disney World and clowding up your mind.. Grin

Seriously, get some sleep! Didn't you just drive 22 hrs?  Cheesy Cheesy

Nick- LMAO
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luvrbus
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« Reply #2 on: June 21, 2009, 03:22:55 PM »

Not going to happen with the same coach and engine driving the same speed you do lose 1 to 2 mpg with a automatic       good luck
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WEC4104
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« Reply #3 on: June 21, 2009, 03:25:14 PM »

Here's the hidden story behind the story... Many of the manual transmission coaches (mine included) are set up with their original engine configuration with quite modest horsepower figures.  The automatics tend to be either later models with bigger engines, or older coaches that had an engine swap performed along with the change to an automatic transmission. Also, because of the age situation, the manual transmissions tend to be in coaches having shorter length and less frontal height.  Not really an apples to apples comparison.

With the engine and coach factors the same, the manual transmissions do tend to yield higher fuel mileage, but not even close to doubling it.
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ttomas
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« Reply #4 on: June 21, 2009, 03:27:31 PM »

I have an auto and get 5.8 to 7.5 mostly 6.5 . I have two friends that I have traveled with , they have manuals. neither one gets very much better if any better. both wished they had automatics.
 FWIW, I say buy a bus for the condition it is in and priced in your range.
It all depends on how you drive it. I have got 8.2 doing 50 to 52mph. It was a trip when I had more time than money.    Hope you get what you want, Tom
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JohnEd
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« Reply #5 on: June 21, 2009, 03:30:39 PM »

IM,

I haven't a clue on conversion costs either way.  But, like you, I have been watching and listening.  Here is my take:  In all the time I have been reading here I have only found one Knut that said a stick was better.  That was "Bob of the North".  His comment to me was that "you are only really shifting the thing when you are off the highway".  Close quote, as I remember.  Bob has a 9 speed Road Ranger but I am fuzzy on details.  Now Bob is a man whose opinion I will take to the bank on any given day but there is a problem.....Bob recently thought he needed an engine replacement and he was going to go with an 8V92 coupled to a 740 auto.  Now, everyone I have noted that expressed an opinion has been for the automatic over the manual.  That has included a "highly respected" Knut that up graded to a "Auto Shift' 13 speed manual.  And he doesn't use the clutch except to start ONCE.   So, as I count the votes, it is 100% for the auto with one iffy renege.  The renege, learning that his engine is OK, isn't going for a auto conversion, I note.  So, I guess the consensus is not "perfect".  The ultimate config seems to be running the engine thru a 6 speed Alyson....NERVANA!  Even the truckers vote for the auto and are often the most adamant of the lot.  I started out thinking a stick would be my preference and I have changed my mind.  I don't want to be the "I'll do it my way Pioneer" with a decision so irrevocable as trans choice, let alone one so contradicted.  For me now!

YMMV,

John
« Last Edit: June 21, 2009, 03:36:54 PM by JohnEd » Logged

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junkman42
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« Reply #6 on: June 21, 2009, 04:07:23 PM »

I average 6.2 with an HT70 which is a true 6 speed automatic and a 8v71.  I can not see any advantage fighting a clutch and shifting in traffic for no gain.  Modern automatics once locked up are no different than a standard transmission.  Just My take.  John
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Len Silva
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« Reply #7 on: June 21, 2009, 05:43:13 PM »

The only people getting 10 MPG are driving older, 35 foot, light weight coaches with a stick in the flats.  If you are driving a 45 foot, 20 ton bus, the mileage is not even a part of your vocabulary.
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« Reply #8 on: June 21, 2009, 05:52:05 PM »

Do all the listings claim "New clutch" also?  Wink You'll hear it all from the seller. If anyone of them had converted their bus to an auto it would have that listed in bold type.
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« Reply #9 on: June 21, 2009, 06:27:08 PM »

The real choice is whether you want to drive with BOTH hands and Feet or one foot and a hand. As you get older that multitasking will cost you more.

One foot on the clutch, one on a go pedal, one hand on the shifter and one hand on the steering wheel, while looking left, right, ahead and to the rear and watching the backup camera, tachometer, water temp & oild pressure gauges...

Hmmmm....

Then to make things worse is having a gabby co-pilot trying to steal what little brain power you have left...

I like automatics.

The trade off is worth saving all the extra effort especially in traffic or when you are tired ( arm weary ).... Oh.. Don't forget that brand new left knee replacement that you will need ( maybe? )....

Nuts... Dave..
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« Reply #10 on: June 21, 2009, 06:36:43 PM »

With my H3 45'  I average 7.2 to 7.8 mpg  and that's with the B500 and near 550HP Series 60..    8.1 mpg was my best coming across the midwest plains last year.
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RJ
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« Reply #11 on: June 21, 2009, 07:45:22 PM »


So I have been browsing around and seeing what is on the market right now, and alot of guys with coaches that have a manual transmission are claiming they get roughly 10-11 mpg on a coach that gets roughly 5-6 mpg with an automatic. 




Iminaccess -

What these guys aren't telling you is how they came up with that 11 mpg figure for their bus.

It's all in the math: 5 mpg around town, and 6 mpg on the highway equals 11 mpg.

See, wasn't that easy??   Cheesy Cheesy Cheesy


Seriously, here's my take on this, after spending 25+ years in the bus industry:

35 foot coaches w/ six cylinder engines: 8 - 11 mpg

35 foot coaches w/ eight cylinder engines: 7 - 9 mpg

40 foot coaches w/ 8V71 or 6V92: 5.5 - 6.5 mpg

40 foot coach w/ 8V92: 5.5 - 7 mpg

40 foot coach w/ electronic S-60: 6.5 - 8 mpg

45 foot coach w/ electronic engine: 6.5 - 8 mpg

40 foot transit bus w/ diesel engine in revenue service: 3.5 - 4 mpg

40 foot transit bus w/ CNG: equivalent of 1.5 - 2.5 mpg (but it's clean air, folk!!)


These are overall averages, with so many variables it's hard to point to one specific and tell you "that's what you're going to get."   

HOWEVER -

Notice that the smaller and lighter the coach, the better the mileage.  Also note that the newer, heavier 45 foot coaches, with the more powerful engines and overdrive transmissions, are getting approximately the same or slightly better mileage than the older 40 footers.

IMHO, it's not worth the expense to convert an automatic back to a manual box for the (generally) 1 - 3 mpg difference in fuel economy.  And the ease of driving an auto, especially in congested urban areas and for most RV folk, far outweigh the slight mileage penalty.

Clear as mud?

FWIW & HTH. . .
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« Reply #12 on: June 21, 2009, 11:35:44 PM »

If you drove an automatic bus chasing a manual transmission bus and kept to the same acceleration rate as the manual bus, you'd find the fuel mileages to be very close to each other.  In fact (and this has been proven over and over), a poorly driven manual transmission bus will get worse mileage then an automatic bus.  The main reason Allison transmission buses gets much worse mileage then the manual transmission bus is that punching the Allison from the light is so much fun-and it burns more fuel. 
The pure truth is-the only difference in efficiency between the manual and Allison is in the first few yards up to about 20 mph-where the Allison's transmission's torque converter will lockup and be as straight through as the manual transmission.  What most don't know (and this is straight from Allison), is that the Allison transmission takes an additional 20hp over the manual transmission to just turn it over to over come the frictional losses caused by the clutch packs dragging through the transmission fluid.  So you do pay a penalty-but properly driven, should only be maybe as much as one gallon more in a hard day of driving.  Personally-I'll take my Allison everytime-so much so, I just had my truck's 13spd overdrive replaced with the Allison HT740 without overdrive.  But with my gearing, I'll have a comfortable cruise at 65mph at 1800rpm-which is just right for my older Caterpillar 3406B mechanical 400hp engine.  Good Luck, TomC
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JackConrad
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« Reply #13 on: June 22, 2009, 06:07:51 AM »

a lot of guys with coaches that have a manual transmission are claiming they get roughly 10-11 mpg on a coach that gets roughly 5-6 mpg with an automatic.

Hey, We get 11 with our automatic (6 on the highway & 5 in town) 5+6=11.  I don't think anyone can change mileage more than by 1-1.5 MPG by simply changing from auto to manual. Driving style, weight, terrain, etc. will also affect MPG.  Jack
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« Reply #14 on: June 22, 2009, 07:34:00 AM »


FUZZY MATH....  I Love It!

 Cheesy Cheesy Grin Cheesy Cheesy Grin Cheesy Cheesy Grin
« Last Edit: June 22, 2009, 07:35:39 AM by Nick Badame Refrig. Co. » Logged

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