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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 08-30-2020, 02:10 PM   #1 (permalink)
EcoModding Lurker
 
Join Date: Aug 2012
Location: Portland, Oregon
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Bedliner paint job effects on wind

I bought an old suzuki samurai and it has what I call a "high school paint job." Where someone just rolled bedliner over the entire thing. With the rough surface everywhere it got me thinking about how much that would potentially effect the wind resistance. I know some studies that say putting golf ball dimples on a car can help but I assume a rough and inconsistent pattern of which a bedliner paint job I think could really hurt your drag and not help. Any guesses by how much?

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 08-30-2020, 03:51 PM   #2 (permalink)
Cyborg ECU
 
California98Civic's Avatar
 
Join Date: Mar 2011
Location: Coastal Southern California
Posts: 6,299

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: 2,373
Thanked 2,174 Times in 1,470 Posts
Assuming "rough" does not mean 10,000 one inch protruberances from the body panels, the answer is most likely "not much or virtually not at all." Most drag is pressure drag, not body friction, from what I have read. I am no expert, just an interested reader.
__________________
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.



  Reply With Quote
The Following User Says Thank You to California98Civic For This Useful Post:
aerohead (09-02-2020)
Old 08-30-2020, 03:57 PM   #3 (permalink)
マット
 
M_a_t_t's Avatar
 
Join Date: Nov 2015
Location: Indiana
Posts: 718

The Van - '95 Chevy Astro Cl V8 Swapped
Team Chevy
90 day: 7.84 mpg (US)

The new bike - '17 Kawasaki Versys X 300 abs
Motorcycle
90 day: 71.94 mpg (US)

The Mercury - '95 Mercury Tracer Trio
Team Ford
90 day: 34.35 mpg (US)

Toyota - '22 Toyota Corolla Hatchback
90 day: 40.11 mpg (US)
Thanks: 131
Thanked 258 Times in 188 Posts
+1 for California98Civic's response. The air immediately touching the body panels is stagnant. As you get farther away from the panel the air speed increases until you get to freestream which is the air speed of the air that is not close to the car. That should be equal to the car's forward speed.

See attached pic for maybe a better explanation. The bottom black line is the surface of the car. The longer the arrow the faster the air is moving along the surface. There aren't any units because it's not something to be set in stone (I think) and is partially dependent on the situation (car in question, speed, etc.). It's called viscous drag. This is also why clay barring a car doesn't really do much (if anything) because the air is stagnant anyway.


My brothers motorcycle was bedlined before he got it. It's an interesting thing to do, but it's held up really well including spilled gas and a few drops. Conversation starter for sure though
Attached Thumbnails
Click image for larger version

Name:	surface speed.jpg
Views:	69
Size:	11.6 KB
ID:	29069  
__________________
1973 Fiat 124 Special
1975 Honda Civic CVCC 4spd
1981 Kawasaki KZ750E
1981 Kawasaki KZ650 CSR
1983 Kawasaki KZ1100-A3
1986 Nissan 300zx Turbo 5 spd
1995 Chevy Astro RWD (current project)
1995 Mercury Tracer
2017 Kawasaki VersysX 300
2022 Corolla Hatchback 6MT

https://www.youtube.com/channel/UC6s...LulDUQ8HMj5VKA

Last edited by M_a_t_t; 08-30-2020 at 04:15 PM..
  Reply With Quote
The Following User Says Thank You to M_a_t_t For This Useful Post:
aerohead (09-02-2020)
Old 08-30-2020, 07:32 PM   #4 (permalink)
Banned
 
Join Date: Nov 2017
Location: Australia
Posts: 2,060
Thanks: 107
Thanked 1,605 Times in 1,136 Posts
Quote:
Originally Posted by eou_edu View Post
I bought an old suzuki samurai and it has what I call a "high school paint job." Where someone just rolled bedliner over the entire thing. With the rough surface everywhere it got me thinking about how much that would potentially effect the wind resistance. I know some studies that say putting golf ball dimples on a car can help but I assume a rough and inconsistent pattern of which a bedliner paint job I think could really hurt your drag and not help. Any guesses by how much?
Ford in 'proper' testing found dimples increased drag.

As people have said, I don't think the bedliner coating will make any measurable difference - especially on that vehicle.

That said, on some specific parts (eg exterior mirror housings) a rough coating has been used to trip the airflow (changing it from laminar to turbulent in boundary layer), so reducing noise. (P 235 of my book, for people who have it.)
  Reply With Quote
The Following User Says Thank You to JulianEdgar For This Useful Post:
aerohead (09-02-2020)
Old 09-09-2020, 06:32 PM   #5 (permalink)
Master EcoModder
 
Join Date: May 2019
Location: California
Posts: 513

2020 - '08 Chevy Tahoe H
Last 3: 18.4 mpg (US)

2021 - '08 Chevy Tahoe H
90 day: 17.08 mpg (US)

2022 - '08 chevy Tahoe LT
Last 3: 14.38 mpg (US)

2023 - '08 Chevy Tahoe
Last 3: 22.61 mpg (US)

2024 - '08 Chevy Tahoe
90 day: 22.35 mpg (US)
Thanks: 2
Thanked 105 Times in 96 Posts
Quote:
Originally Posted by JulianEdgar View Post
Ford in 'proper' testing found dimples increased drag.

As people have said, I don't think the bedliner coating will make any measurable difference - especially on that vehicle.

That said, on some specific parts (eg exterior mirror housings) a rough coating has been used to trip the airflow (changing it from laminar to turbulent in boundary layer), so reducing noise. (P 235 of my book, for people who have it.)
mythbusters tested it but they made a small error by not removing the spoiler

  Reply With Quote
Reply  Post New Thread






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