Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 02-28-2018, 06:14 PM   #1 (permalink)
EcoModding Apprentice
 
Join Date: May 2012
Location: United States
Posts: 128
Thanks: 14
Thanked 15 Times in 8 Posts
Why isn't 6th gear super tall?

Just got a 03 Audi 6 speed v6 A4. mpg is 27 going about 80 mph all day.
RPMs are 3000 going 80 when V6 horsepower can easily move the car in any gear at 2000 RPM. Why don't car makers make a super efficient 6th gear to drop the RPMs so it get super highway MPG?

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 02-28-2018, 06:32 PM   #2 (permalink)
Master EcoModder
 
Join Date: Feb 2014
Location: Missoula, MT
Posts: 2,652

Dark Egg - '12 VW Touraeg
Thanks: 300
Thanked 1,176 Times in 806 Posts
They build it to get good number on the EPA test cycle and the EPA test cycle doesn't go that fast. They want the sweet spot to be at the test speed. There is probably also a point where the gears would be too much of a drop in RPM or just too much strain on the parts themselves. There is also a limit in the size of a transmission between the input and output shafts that the difference in what the lowest gear to the highest gear can be. To make that separation bigger they would have to increase the separation of the shafts. So it's probably a combination of all 3. I bet bottom line, if they could make the EPA number better they would do it even if they had to re-design everything else to work with it.
  Reply With Quote
The Following User Says Thank You to Hersbird For This Useful Post:
SmellyCat (02-28-2018)
Old 02-28-2018, 07:15 PM   #3 (permalink)
Just cruisin’ along
 
jcp123's Avatar
 
Join Date: Jul 2009
Location: Rochester, NY
Posts: 1,183

Beater Echo - '00 Toyota Echo
90 day: 42.67 mpg (US)

Hondizzle - '97 Honda Civic DX
Team Honda
90 day: 46.55 mpg (US)

Shaggin Waggin - '14 Chrysler Town + Country
90 day: 22.56 mpg (US)
Thanks: 66
Thanked 200 Times in 170 Posts
^^ there's probably truth in that. And I'd also add that customers might complain that the car feels a little "doggy" with taller gearing, which would be a marketing problem for them.
__________________



'97 Honda Civic DX Coupe 5MT - dead 2/23
'00 Echo - dead 2/17
'14 Chrysler Town + Country - My DD, for now
'67 Mustang Convertible - gone 1/17
  Reply With Quote
The Following 2 Users Say Thank You to jcp123 For This Useful Post:
Daschicken (03-01-2018), SmellyCat (02-28-2018)
Old 02-28-2018, 08:37 PM   #4 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,561
Thanks: 7,736
Thanked 8,554 Times in 7,041 Posts
Gearboxes in general are classified as close-ratio and wide ratio. Close-ratio is for sportscars, wide-ratio is for trucks. If sixth is raised at the very least fifth would have to move as well.

Audi might want to sell to people who ski, with lots of friends.
__________________
.
.
Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster

____________________
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
SmellyCat (02-28-2018)
Old 02-28-2018, 09:00 PM   #5 (permalink)
EcoModding Apprentice
 
Join Date: May 2012
Location: United States
Posts: 128
Thanks: 14
Thanked 15 Times in 8 Posts
I had a auto two gear ford falcon, a 3 gear mustang, multiple 4 gear trucks and cars . Many 5 speeds. Now I got this 240 hp 6 speed . If I'm just coasting around, I skip gears due to getting bored with all the gears. I say " I want 5 gears for driving, and if there is a a 6th. It better be frickin tall so I save gas on the freeway. gosh darn it!
Yes, I do rev it up and enjoy the heck out of it, but I can't act like a 17 year old all the time anymore.
  Reply With Quote
Old 02-28-2018, 09:13 PM   #6 (permalink)
EcoModding Apprentice
 
Join Date: May 2012
Location: United States
Posts: 128
Thanks: 14
Thanked 15 Times in 8 Posts
Permalink, if I drive 40 mph in 6th, I get 40 plus mpg on display, tach shows about 1700 rpm. Engine takes it fine, no knock or lug. I see your point. EPA tests and all. Avg fleet mpg. Still a taller 6th would seem to help make the results better. It would also increase top speed I reckon.
  Reply With Quote
Old 02-28-2018, 09:19 PM   #7 (permalink)
Human Environmentalist
 
redpoint5's Avatar
 
Join Date: Aug 2010
Location: Oregon
Posts: 12,390

Acura TSX - '06 Acura TSX
90 day: 24.19 mpg (US)

Lafawnda - '01 Honda CBR600 F4i
90 day: 47.32 mpg (US)

Big Yeller - '98 Dodge Ram 2500 base
90 day: 21.82 mpg (US)

Prius Plug-in - '12 Toyota Prius Plug-in
90 day: 57.64 mpg (US)

Mazda CX-5 - '17 Mazda CX-5 Touring
90 day: 26.68 mpg (US)

Chevy ZR-2 - '03 Chevrolet S10 ZR2
90 day: 17.14 mpg (US)
Thanks: 4,188
Thanked 4,378 Times in 3,353 Posts
This is among my favorite gripe topics. Your gearing is way better than my Acura. My 6th gear has me doing about 65 MPH at 3000 RPM.

The thing is, 6th is completely worthless as a racing gear. It would take several miles of a straight racetrack for me to top 5th gear out. A jumbo jet runway isn't long enough for me to reach 6th in a drag race. But, it's so short that it isn't any use cruising on the highway at 60 MPH either.

It sucks at everything!

If Acura had programmed the VTEC to kick in at somewhere less than 6,000 RPM (yes, that is when it begins to work), then the gears wouldn't have to be so closely spaced.

I've thought about putting an RSX final into the TSX, but it would only marginally help tame the RPMs.

Other than that, and the car having the turning radius of a train, it's a perfect car.
__________________
Gas and Electric Vehicle Cost of Ownership Calculator







Give me absolute safety, or give me death!
  Reply With Quote
Old 02-28-2018, 10:45 PM   #8 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,561
Thanks: 7,736
Thanked 8,554 Times in 7,041 Posts
I put a five-speed in my (normally four-speed) VW Type III notchback. I shifted up into fifth at 85mph.

The advantage came in having one more choice for gearing driving around town.
__________________
.
.
Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster

____________________
  Reply With Quote
Old 02-28-2018, 11:22 PM   #9 (permalink)
Furry Furfag
 
Baltothewolf's Avatar
 
Join Date: Nov 2013
Location: Apple Valley
Posts: 2,084

Winsight - '00 Honda Insight
90 day: 56.69 mpg (US)

Miaderp - '95 Mazda Miata
90 day: 28.53 mpg (US)
Thanks: 67
Thanked 409 Times in 313 Posts
The new Civic Si has an amazing 6-speed. 1-3 is as short as the old NA Miata's (VERY short). Then 4-5 is fairly tall, and 6th is really tall. I believe 6th at 80mph is 3000rpm. I know 6th at 70 is 2700, which is about what the honda insight is in 5th. Guess that's why it's rated for 41mpg highway.
__________________

  Reply With Quote
The Following User Says Thank You to Baltothewolf For This Useful Post:
samwichse (03-01-2018)
Old 03-01-2018, 02:47 AM   #10 (permalink)
It's all about Diesel
 
cRiPpLe_rOoStEr's Avatar
 
Join Date: Oct 2012
Location: Porto Alegre, Rio Grande do Sul, Brazil
Posts: 12,548
Thanks: 0
Thanked 1,622 Times in 1,447 Posts
Most of the times a 6th gear is worthless at all, and sometimes a 5-speed transmission may actually lead to a better mileage compared to a 6-speed. But anyway, instead of a taller 6th, if I had the choice I'd get a wide-ratio transmission with a higher gear spread and match it to a higher differential.

  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com