Go Back   EcoModder Forum > EcoModding > General Efficiency Discussion
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-02-2013, 07:43 PM   #1 (permalink)
It's all about Diesel
 
cRiPpLe_rOoStEr's Avatar
 
Join Date: Oct 2012
Location: Porto Alegre, Rio Grande do Sul, Brazil
Posts: 7,185
Thanks: 0
Thanked 730 Times in 644 Posts
Less engine, more gears

Yesterday while I was walking in the neighborhood with my dog, I spotted one of the first eco-cars I fell in love for. The Fiat Palio Weekend 6 marchas was available only in '99 and 2000, with a 61hp/60lb.ft. 1.0L engine backed by a 6-speed (6 marchas) manual transmission, while the previous base versions had a 75hp/90lb.ft. 1.5L and a 5-speed manual instead.





Altough at some point a significantly lower displacement won't actually help, the gears always play an important role for both performance and efficiency.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-02-2013, 08:12 PM   #2 (permalink)
Master EcoModder
 
Join Date: May 2012
Location: Indiana
Posts: 1,519

Volt, gas only - '12 Chevrolet Volt Premium
90 day: 38.02 mpg (US)

Volt, electric only - '12 Chevrolet Volt Premium
90 day: 132.26 mpg (US)

Yukon Denali Hybrid - '12 GMC Yukon Denali Hybrid
90 day: 21.48 mpg (US)
Thanks: 164
Thanked 333 Times in 232 Posts
Higher gear count transmissions are definitely gaining popularity, in the near future chrysler will be using solely 8 and 9 speed transmissions. Aerodynamics is also a hugely important aspect, the public doesn't want to drive slower so the only way to get those high mpg numbers is small turbo engines, lots of gears and very aerodynamic bodies.
__________________




  Reply With Quote
Old 08-02-2013, 09:15 PM   #3 (permalink)
...beats walking...
 
Join Date: Jul 2009
Location: .
Posts: 6,191
Thanks: 179
Thanked 1,521 Times in 1,122 Posts
...gears are becoming like Archimedes' geometric approximations of a circle, just use enough small-length, straight, segments to approximate a smooth circle made of straight pieces...ie, use enough 'staight' gears to approximate a 'smoothly curving' power-vs.-load curve: a geared CVT.
  Reply With Quote
The Following User Says Thank You to gone-ot For This Useful Post:
IamIan (08-03-2013)
Old 08-03-2013, 06:06 AM   #4 (permalink)
Eco-ventor
 
jakobnev's Avatar
 
Join Date: Oct 2010
Location: sweden
Posts: 1,209

Princess - '92 Mazda MX-3 GS
House of Tudor
Team Mazda
90 day: 53.54 mpg (US)
Thanks: 48
Thanked 409 Times in 259 Posts
Send a message via MSN to jakobnev
My car has six forward gears too: 1-2-3-4-5 and Neutral!
__________________




2016: 128.75L for 1875.00km => 6.87L/100km (34.3MPG US)
2017: 209.14L for 4244.00km => 4.93L/100km (47.7MPG US)
  Reply With Quote
The Following 2 Users Say Thank You to jakobnev For This Useful Post:
Fat Charlie (09-03-2013), mechman600 (08-06-2013)
Old 08-03-2013, 07:10 AM   #5 (permalink)
Master EcoModder
 
nemo's Avatar
 
Join Date: Nov 2010
Location: US
Posts: 907

Chief - '06 Pontiac Grand Prix
90 day: 27.29 mpg (US)

SF1 - '12 Ford Fiesta S
90 day: 36.87 mpg (US)
Thanks: 160
Thanked 198 Times in 154 Posts
Quote:
Originally Posted by jakobnev View Post
My car has six forward gears too: 1-2-3-4-5 and Neutral!
And two reverse?
__________________

  Reply With Quote
Old 08-03-2013, 12:44 PM   #6 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,563

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,515
Thanked 3,330 Times in 2,102 Posts
What do you gain with all those gears? If your deal is max acceleration rate, that is what you gain. If your deal is fe, you lose from all that shifting- a most inefficient process what with all that throttle blipping and halting forward motion- and you lose from a transmission that has more moving parts and I would imagine more internal friction.

In the '80s the eco-stick trans options were 4-speed instead of 5.

With my 5-speeds I'm always skip shifting, like 1-3-5. I would like to only have the 1-3-5 gears and throw 2-4 away and save the internal trans losses.
__________________


  Reply With Quote
Old 08-03-2013, 04:44 PM   #7 (permalink)
Master EcoModder
 
IamIan's Avatar
 
Join Date: Dec 2010
Location: RI
Posts: 666
Thanks: 365
Thanked 212 Times in 130 Posts
Like most things there are pros and cons.
  • Pro: More gear ratio options allows a better ability to convert the real time road torque and RPM situation into a combination that is at more efficient point on a ICE's BSFC.
  • Con: Manual transmissions has a loss of efficiency during the shifting period ... the more one has to shift the more shifting losses... more gears means more shifting over the same RPM and torque transition.
  • Pro: Manual transmissions can be more energy efficient from input to output.
  • Con: Finite Manual Transmissions have fewer gear options than other 'CVT' and the like ... ie they are less able to have the 'best' ICE gear ratio for all road torque and RPM conditions.

I have a interesting paper about the efficiencies of various transmissions.
Sadly it is not free... Link

But ... here are some teasers / interesting bits from the testing in it.

PumpCVT

Manual

Toroidal

BeltCVT

BallPump

FixedDisplacementPump

Automatic

Last edited by IamIan; 08-03-2013 at 04:51 PM..
  Reply With Quote
Old 08-03-2013, 11:56 PM   #8 (permalink)
Master EcoModder
 
Join Date: Jun 2008
Location: Earth
Posts: 5,209
Thanks: 225
Thanked 803 Times in 589 Posts
Quote:
Originally Posted by Frank Lee View Post
What do you gain with all those gears? If your deal is max acceleration rate, that is what you gain. If your deal is fe, you lose from all that shifting- a most inefficient process what with all that throttle blipping and halting forward motion- and you lose from a transmission that has more moving parts and I would imagine more internal friction.
I dunno. My bikes seem to do pretty well with 21/24 speeds - though I could always use a few more :-)
  Reply With Quote
Old 08-04-2013, 01:25 AM   #9 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,563

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,515
Thanked 3,330 Times in 2,102 Posts
Right- and you go from 1st through each gear to 24th from a stop.

There was some guy on here that thought everything should have 18 or so speeds; maybe he likes to spend all his time shifting- I consider it a necessary evil.
__________________


  Reply With Quote
Old 08-04-2013, 07:48 AM   #10 (permalink)
Master EcoModder
 
nemo's Avatar
 
Join Date: Nov 2010
Location: US
Posts: 907

Chief - '06 Pontiac Grand Prix
90 day: 27.29 mpg (US)

SF1 - '12 Ford Fiesta S
90 day: 36.87 mpg (US)
Thanks: 160
Thanked 198 Times in 154 Posts
If the vehicle is driven on relatively flat terrain, a manual transmission with four speeds is sufficient three was the norm for years. The problem is in most manual transmission the top gear does not get the rpms down low enough for best fuel economy. This seems to be the case whether equipped with a three, four or five speed. No personal experience with a six speed in a car. It’s as if the transmission is designed so under most driving condition you will not need to drop it down a gear. In the mountains it is nice to have multiple gear choices. In this case a 5 speed is better, especially if you have a low hp low torque car. Wouldn't it be nice if you had choices like the first four to be close ratio and fifth out in left field for economy.As gargantuan motors and the heard followers only want to sell the 20% of the vehicles that appeal to 80 % of the market. you are lucky to get what you want, to find it with a manual transmission a gem.

As for high gear count automatics just sounds more expensive to build and repair.

__________________

  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com