Go Back   EcoModder Forum > EcoModding > Hypermiling / EcoDriver's Ed
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 11-02-2012, 02:15 PM   #11 (permalink)
Master EcoModder
 
Sven7's Avatar
 
Join Date: Aug 2011
Location: Warren, MI
Posts: 2,456

Boo Radley - '65 Ford F100
90 day: 13.28 mpg (US)
Thanks: 782
Thanked 667 Times in 409 Posts
Quote:
Originally Posted by JRMichler View Post
The difference in aerodynamic drag is proportional to the square of the airspeed, or 40%.
Say that again?

Airspeed squared is the aero difference?

So, if I were going 10 mph faster, it would be 10*10...oh, I give up

__________________
He gave me a dollar. A blood-soaked dollar.
I cannot get the spot out but it's okay; It still works in the store
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 11-02-2012, 02:28 PM   #12 (permalink)
Hypermiler
 
PaleMelanesian's Avatar
 
Join Date: Dec 2007
Location: Texas
Posts: 2,321

PaleCivic (retired) - '96 Honda Civic DX Sedan
90 day: 69.2 mpg (US)

PaleFit - '09 Honda Fit Sport
Team Honda
Wagons
90 day: 44.06 mpg (US)
Thanks: 611
Thanked 433 Times in 283 Posts
Quote:
Originally Posted by JRMichler View Post
But, at 60 MPH, that is the difference between 55 MPH and 65 MPH airspeed depending whether it's a tailwind or a headwind. The difference in aerodynamic drag is proportional to the square of the airspeed, or 40%.
Correct. In this case, the two airspeeds are 55 mph and 65 mph.

65^2 = 4225
55^2 = 3025
4225/3025 = 1.397, or about 40% higher.

Or to put it another way, 10 mph over 55 is an 18% difference. 1.18*1.18 = 1.39, or again almost 40%.
__________________



11-mile commute: 100 mpg - - - Tank: 90.2 mpg / 1191 miles
  Reply With Quote
Old 11-02-2012, 03:13 PM   #13 (permalink)
Master EcoModder
 
mcrews's Avatar
 
Join Date: Oct 2009
Location: Texas
Posts: 3,523

The Q Sold - '02 Infiniti Q45 Sport
90 day: 23.08 mpg (US)

blackie - '14 nissan altima sv
Thanks: 2,203
Thanked 663 Times in 478 Posts
Quote:
Originally Posted by JRMichler View Post
And once upon a time I got 41 MPG out of a 1995 Dodge Neon at 80 MPH. But it was a warm summer day, I was moving with traffic in the fast lane, and a tail wind.

Wind has a huge effect. Most people cannot even feel a five MPH wind. But, at 60 MPH, that is the difference between 55 MPH and 65 MPH airspeed depending whether it's a tailwind or a headwind. The difference in aerodynamic drag is proportional to the square of the airspeed, or 40%.
Reminded me of several of my crosscountry trips from CA to texas when I would be on the high plains on hwy 40.
Once I could literally feel the car being pushed along!!!!!
Another time the cross winds had all the cb anteneas leaning at 45degree angles!!!
__________________
MetroMPG: "Get the MPG gauge - it turns driving into a fuel & money saving game."

ECO MODS PERFORMED:
First: ScangaugeII
http://ecomodder.com/forum/showthrea...eii-23306.html

Second: Grille Block
http://ecomodder.com/forum/showthrea...e-10912-2.html

Third: Full underbelly pan
http://ecomodder.com/forum/showthrea...q45-11402.html

Fourth: rear skirts and 30.4mpg on trip!
http://ecomodder.com/forum/showthrea...tml#post247938
  Reply With Quote
Old 11-03-2012, 07:59 AM   #14 (permalink)
EcoModding Lurker
 
Join Date: Oct 2012
Location: muskoka
Posts: 81

Speedy Gonzales - '11 Ford Fiesta SES
Thanks: 7
Thanked 11 Times in 7 Posts
Something that wasn't touched on here is the possibility of the engine running more efficiently at the higher speed (higher rpm) than the lower rpm.
It could be the engine "coming on the cam", getting the best scavenging from the exhaust, both the tuning of the intake/exhaust plumbing, thermal dynamics inside the combustion chamber...etc.

Makes sense to me to have a target rpm range where a typical engine runs the most efficient...especially if this engine is connected to a CVT transmission...which isn't the case here, but just saying...
  Reply With Quote
Old 11-03-2012, 01:42 PM   #15 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
wungun - It's possible, of course. Diesel Dave touched on that idea in post #8.

But it's pretty unlikely. Actually it would be the first modern, conventional 4-cyl car anyone's seen around here that behaves that way.
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 11-03-2012, 01:54 PM   #16 (permalink)
EcoModding Lurker
 
Join Date: Oct 2012
Location: UK
Posts: 8
Thanks: 0
Thanked 1 Time in 1 Post
Guess i speak a foreign language
  Reply With Quote
Old 11-03-2012, 02:01 PM   #17 (permalink)
GRU
Master EcoModder
 
GRU's Avatar
 
Join Date: Oct 2011
Location: Windsor ON Canada
Posts: 373

silver bullet - '00 Honda Civic
90 day: 34.41 mpg (US)
Thanks: 21
Thanked 37 Times in 32 Posts
I have driven my car on the same road. At the same speed. At the same time ( reseting the trip mpg every 2 minutes ) and got different numbers every time because its almost impossible to have the same exact conditions even if they are only 2 minutes apart
__________________

  Reply With Quote
Old 11-04-2012, 03:17 AM   #18 (permalink)
EcoModding Lurker
 
Join Date: Sep 2012
Location: Oakland, CA
Posts: 44

Lincoln - '00 Lincoln Ls
90 day: 24.29 mpg (US)
Thanks: 10
Thanked 3 Times in 2 Posts
Wow, I knew that air resistance grew exponentially, but I didn't realize that a difference in 10 mph could make such a difference.

I wonder: What if trees were planted along all the highways? Once the trees grow, wouldn't that dramatically reduce wind resistance?

Although that might also reduce the benefits of a tailwind.
  Reply With Quote
Old 11-04-2012, 09:01 AM   #19 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
Quote:
Originally Posted by DirtyTorquer View Post
Guess i speak a foreign language
Whoops! Yes, you talked about it too.
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 11-04-2012, 09:24 AM   #20 (permalink)
EcoModding Lurker
 
Join Date: Oct 2012
Location: muskoka
Posts: 81

Speedy Gonzales - '11 Ford Fiesta SES
Thanks: 7
Thanked 11 Times in 7 Posts
Quote:
Originally Posted by wobombat View Post
Wow, I knew that air resistance grew exponentially, but I didn't realize that a difference in 10 mph could make such a difference.

I wonder: What if trees were planted along all the highways? Once the trees grow, wouldn't that dramatically reduce wind resistance?

Although that might also reduce the benefits of a tailwind.
Exponentially means just that...
And easy way to look at it is, to double your speed requires 4times the power.
So if your increasing your speed from 10mph to 20mph, it'll still require 4 times the power...except at those speeds, you might only be using 3hp to maintain 10mph (or 12hp for 20mph.)
But if you're doing 50mph, and you want to do 100mph, where it might be 50hp to do 50, you'll need 200hp to do 100mph...and exponential jump!

Someone correct me if I'm wrong....

__________________

  Reply With Quote
Reply  Post New Thread


Tags
camry

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