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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 04-20-2020, 03:08 AM   #11 (permalink)
herp derp Apprentice
 
Join Date: Oct 2008
Location: Lawrence, KS
Posts: 1,044

Saturn-sold - '99 saturn sc1
Team Saturn
90 day: 28.28 mpg (US)

Yukon - '03 GMC Yukon Denali
90 day: 15.11 mpg (US)
Thanks: 43
Thanked 323 Times in 229 Posts
https://ecomodder.com/forum/showthre...ard-28594.html
I tried a similar test on my Saturn, unfortunately everything on the car warming up more and more skewed my measurements. Looked like bare steel wheels did the worst for me, but smooth vs factory hubcaps were very similar to each other

  Reply With Quote
The Following User Says Thank You to 2000mc For This Useful Post:
COcyclist (04-24-2020)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 04-20-2020, 03:22 AM   #12 (permalink)
Master EcoModder
 
JulianEdgar's Avatar
 
Join Date: Nov 2017
Location: Australia
Posts: 1,115
Thanks: 69
Thanked 925 Times in 609 Posts
Quote:
Originally Posted by COcyclist View Post
[...] I recently purchased Julian Edgar’s book and he quotes several studies of airflow and drag on car wheels. These studies show that totally smooth wheel covers are not the lowest drag option in modern automobiles. [...]
Yes, I was surprised with what the formal (SAE-level) research papers showed re full wheel covers. I think a key point is that the wheel drag cannot be looked at in isolation eg the Tesla paper that showed how ventilation airflow through the front wheels could benefit overall drag (despite the wheels themselves then having more drag). My gut feeling is that wheel designs should be asymmetric front/back.

Congrats on your testing.

(Incidentally, I have a video coming up on some recent Porsche results on wheel drag and brake cooling. My channel - https://www.youtube.com/channel/UCK9...mNB9XEmuiCjxcQ)
  Reply With Quote
The Following 2 Users Say Thank You to JulianEdgar For This Useful Post:
aerohead (04-22-2020), Bicycle Bob (08-07-2020)
Old 04-20-2020, 09:51 AM   #13 (permalink)
Master EcoModder
 
JRMichler's Avatar
 
Join Date: Feb 2011
Location: Phillips, WI
Posts: 976

Nameless - '06 GMC Canyon
90 day: 35.1 mpg (US)
Thanks: 186
Thanked 404 Times in 259 Posts
I also found no improvement with wheel covers: https://ecomodder.com/forum/showthre...yon-32761.html.
__________________
The vacuum gauge plus wheel covers helped increase summer 2015 mileage to 38.5 MPG, while summer 2016 mileage was 38.6 MPG without the wheel covers. Drove 33,021 miles 2016-2018 at 35.00 MPG.
  Reply With Quote
Old 04-20-2020, 12:48 PM   #14 (permalink)
Aero Wannabe
 
COcyclist's Avatar
 
Join Date: Dec 2007
Location: NW Colo
Posts: 648

TDi - '04 VW Golf
TEAM VW AUDI Group
90 day: 53.89 mpg (US)
Thanks: 536
Thanked 166 Times in 130 Posts
More thoughts

I realized last night as I was entering the test data that if you only look at the averages, my results show the covered rims give a slight improvement over the bare alloy rims. As I noted in that post my final run may have been impacted by heavier traffic. Also, those runs were later in the day when winds are typically higher, gusting and variable here in the high desert. This makes it harder to get good data. I have tried various forms of the wheel covers over 12 years of driving VW TDI and my tank mpg averages would always go down when I used them. My best mpg tanks all occurred on summer tires with the bare alloy rims. I was puzzled by this so I assumed my wheel covers were somehow deflecting and trapping oncoming air. I doubled up on the wire ties. No improvement. My first attempt was larger, matching the widest part of the tire, so I tried a smaller set. No improvement. I assumed the ties through the spokes were too close to the center so I moved them closer to the circumference. No improvement. I purchased Julian Edgar’s new book- Modifying the Aerodynamics of Your Road Car, and found some information that could explain why I was not seeing positive results from this widely accepted modification.
__________________
60 mpg hwy highest, 50+mpg lifetime
TDi=fast frugal fun
https://ecomodder.com/forum/showthre...tml#post621801


Quote:
Originally Posted by freebeard View Post
The power needed to push an object through a fluid increases as the cube of the velocity. Mechanical friction increases as the square, so increasing speed requires progressively more power.
  Reply With Quote
The Following User Says Thank You to COcyclist For This Useful Post:
aerohead (04-22-2020)
Old 04-20-2020, 02:48 PM   #15 (permalink)
Cyborg ECU
 
California98Civic's Avatar
 
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,092

Black and Green - '98 Honda Civic DX Coupe
Team Honda
90 day: 66.42 mpg (US)

Black and Red - '00 Nashbar Custom built eBike
90 day: 3671.43 mpg (US)
Thanks: 2,307
Thanked 2,025 Times in 1,380 Posts
I don't think it is heresy. The point about smooth discs has been published professionally. In the wheel discs showcase thread I posted a citation to a great informative essay (with pictures!). In short, smooth is very good but not the best. Here is the link: https://ecomodder.com/forum/showthre...tml#post603176
__________________
See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.




Last edited by California98Civic; 04-20-2020 at 05:26 PM.. Reason: confusing typos
  Reply With Quote
Old 04-20-2020, 06:23 PM   #16 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,741

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: 1,573
Thanked 3,510 Times in 2,197 Posts
Quote:
Originally Posted by COcyclist View Post
Kudos to anyone who decides to do A-B-A testing. To do it right takes time and ideal test conditions to get good results. <> There seemed to be more variation with changing wind perhaps, than the variation of wheel covers on or off.
Back in another epoch I did a college paper on aerodynamic devices and road-tested the standard fare: air dam, skirts, shovel-nose grille block, mirror deletes, etc. As much as I wanted my devices to create earth-shattering improvements to be honest they didn't rise above the signal-to-noise ratio of on-road testing and I had to admit as much in the paper. One reason I'm loathe to make mpg claims for mods is I know first-hand how hard it is to get good trustworthy data.
__________________


  Reply With Quote
The Following 2 Users Say Thank You to Frank Lee For This Useful Post:
COcyclist (04-21-2020), MeteorGray (04-21-2020)
Old 04-21-2020, 07:50 AM   #17 (permalink)
EcoModding Apprentice
 
Join Date: Jul 2015
Location: Louisiana
Posts: 247
Thanks: 154
Thanked 91 Times in 74 Posts
I don't see how data can be trusted unless the effects of wind can be controlled (amongst other things, of course.)

So, testing in variable winds is a deal killer, for me.
__________________
  Reply With Quote
Old 04-22-2020, 11:59 AM   #18 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 11,786
Thanks: 18,992
Thanked 6,098 Times in 3,740 Posts
busted

Quote:
Originally Posted by COcyclist View Post



At least on the VW Golf


https://imgur.com/gallery/7sVGG7k


I have tried various forms of wheel covers for over 10 years on my diesel Golf 5 speed manual with no real improvement in highly mpg. I have had several entire tanks testing them where the mpg seems to go down. Wheel covers are one of the first mods many people try on this forum. There is a historical tradition of using Moon wheel covers on salt flats and intuitively they “look” like they would work much better than the blender blade mess of most alloy rims. I recently purchased Julian Edgar’s book and he quotes several studies of airflow and drag on car wheels. These studies show that totally smooth wheel covers are not the lowest drag option in modern automobiles. This would fit with my personal experience and motivated me to do some further testing in an A-B-A or even A-B-A-C-D options. I will post my test data and observations in a following post.
How does that conclusion square with counterfactual evidence achieved from direct wind tunnel measurement? Why is Julian authorized to overturn nearly a century of observations and measurements?
How many,out of the total population of 'modern' cars are represented in these remarkable findings?
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Old 04-22-2020, 12:07 PM   #19 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 11,786
Thanks: 18,992
Thanked 6,098 Times in 3,740 Posts
road trips

Quote:
Originally Posted by COcyclist View Post


The VW GTI alloy 9 spoke rim gave me the best mpg in 2 days of testing and previous extended road trips. The alloy rims alone were better than with flat coroplast wheel covers.

Edit- It turns out this statement may be slightly misleading. Read on
The likelihood of isolating the drag contribution of wheels on a road trip is highly dubious.The SAE would never say it's even possible.This would be something which could only be confirmed in a wind tunnel.And the same wind tunnel,if done on separate days of testing.
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Old 04-22-2020, 01:20 PM   #20 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 11,786
Thanks: 18,992
Thanked 6,098 Times in 3,740 Posts
smooth wheels

I went back to the:
Index of Phil Knox Aerodynamic Seminars & Mod-data lists,under, Mod-data Lists: #7.
General Motors investigators found that the John Shinella aero wheels (think MOON wheels) for the Pontiac Trans Am,returned 0.027 lower drag than the open,standard steel wheels,as measured at the Lockheed,Marietta,Georgia full-scale wind tunnel.

__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
The Following User Says Thank You to aerohead For This Useful Post:
California98Civic (04-22-2020)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com