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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 02-27-2021, 05:59 AM   #1 (permalink)
The manic mechanic
 
Join Date: Jun 2013
Location: Chicago, IL
Posts: 15

Hondo - '03 Hyundai accent gl
90 day: 33.81 mpg (US)
Thanks: 2
Thanked 6 Times in 2 Posts
A-B-C-A tested spare tire aero mod to 2nd gen Highlander Hybrid

Recently my wife and I purchased a 2013 Toyota highlander hybrid which I absolutely love. Having been out of the ecomodding game for several years this got me excited. Plans include a roof rail delete, full belly pan, and wheel covers as the 19" alloys aren't aero friendly, but that's for future posts. The subject of my first serious ABA test is the spare tire. Toyota carries this on the undercarriage of this vehicle with a retractable cable winch to raise and lower it, just forward of the rear bumper. To stop the steel piece that holds the rim through the center of the hub from scratching the face of the rim over time, the wheel is carried face up, leaving the open back of the rim pointing down towards the road and while it is raked rearward, it doesn't look good to me (like turbulence). Not wanting to do a full delete of the spare I grabbed one of those cheap ($18) vinyl spare tire covers from the auto parts store and put it on the underside of the spare to clean up the airflow like its own belly pan, just less effective.

A quick note:
The elastic on the 27-29" spare cover was too tight to get it on and off the wheel without tools though the cover did just barely fit. I cut the elastic and using steel tie wire, fished some paracord through in its place so I could just tie it off like sweat pants and not have to fight with it; glad I did.

Now I live a bit outside of Chicago so highway traffic conditions will never be perfect for testing but I did my best to account for the important factors.

I began my trips with the tire cover on; went out then back on my test loop, then did the loop again with the cover removed, like stock. Then a third loop with the whole spare completely removed, but inside the vehicle, and finally a fourth loop with the cover installed again as the initial rain from just the first loop had stopped. For all the runs my data was taken from the factory trip mileage reading which I reset in the same places each time after reaching a target speed and setting cruise control. my loop was aprox.14 miles of I55 (from Lagrange rd. southwest to Weber if any locals are wondering) on decent pavement, light overnight traffic, and including some small hills. I stayed in the far right lane and tried to avoid any drafting.

I assumed the gains from this test would be small so as much precision as I could manage was needed. I did have the fan, radio, and heated seat on, but at the same settings for all runs.

The run data:

A1,
cover on. 35F, wind S @3.5mph.
28.7mpg @ 61mph; light rain, light traffic

A2
cover on. 33F, wind S @ 5.8mph
31.0mpg @ 60.5mph had to coast and speed back up in once place but good traffic otherwise. light rain
Cover average: 29.85

B1,
cover off. 37F, wind S @6.9mph
29.1mpg @61mph. rain stopped, traffic clear

B2
cover off. 34F wind south @6.9mph
30.3mpg @ 60.5mph. no rain, traffic clear. perfect run
No cover average: 29.7

C1
spare tire inside vehicle. 37F, wind s @6.9mph
28.8mpg @ 60.5mph great traffic, no rain just road mist

C2
spare inside. 33F wind south @ 5.8mph
31.6mpg @ 60.5mph. misty, briefly ended up in a truck's wake
no spare average: 30.2

A3
spare reinstalled with tire cover. 36F, wind southeast @ 6.9mph
27.8mpg @61mph. misty, no real traffic
A4
spare in cover on. 33F, wind south @5.8mph.
30.7mpg @60.5mph. foggy but no rain, ideal traffic
cover on round 2 average:29.25

so as I suspected the gains, if any, might be too small to measure at this level with this equipment.

some takeaways:
-Maybe the tire cover did help a teeny bit but due to minimal unintended drafting in the no spare test as well as very few vehicles in the final cover-on tests to "go with the flow" with may have skewed the data.
-Perhaps the no spare case creates a vortex in the rear bumper like you get in a pickup truck bed?
-Perhaps the airflow is already detached and so turbulent underneath at that point that it makes no difference?
-tuft testing is needed.

Attached Thumbnails
Click image for larger version

Name:	153493625_260703275520537_1154776572739466610_n.jpg
Views:	46
Size:	38.2 KB
ID:	30245   Click image for larger version

Name:	149598664_2804009103248588_7845447048246430401_n.jpg
Views:	54
Size:	93.6 KB
ID:	30246   Click image for larger version

Name:	154971866_1215764542172793_5451664436273221787_n.jpg
Views:	57
Size:	65.3 KB
ID:	30247   Click image for larger version

Name:	150996599_135872545086116_4275117260685023618_n (1).jpg
Views:	35
Size:	69.1 KB
ID:	30248  
__________________

  Reply With Quote
The Following 5 Users Say Thank You to ElPants21 For This Useful Post:
Cd (02-27-2021), Drifter (05-10-2022), Ecky (02-27-2021), MetroMPG (03-25-2021), M_a_t_t (02-27-2021)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 02-27-2021, 09:54 AM   #2 (permalink)
マット
 
M_a_t_t's Avatar
 
Join Date: Nov 2015
Location: Indiana
Posts: 715

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 257 Times in 187 Posts
My guess is that the air flow is so turbulent it made little/no difference.

However, could you use the winch part to attach a board (plywood or a small aluminum frame, whatever is easier) by sandwiching the spare between it and then attach a diffuser/ partial belly pan?
__________________
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
  Reply With Quote
The Following 2 Users Say Thank You to M_a_t_t For This Useful Post:
ElPants21 (02-27-2021), MetroMPG (03-25-2021)
Old 02-27-2021, 10:27 AM   #3 (permalink)
The manic mechanic
 
Join Date: Jun 2013
Location: Chicago, IL
Posts: 15

Hondo - '03 Hyundai accent gl
90 day: 33.81 mpg (US)
Thanks: 2
Thanked 6 Times in 2 Posts
Quote:
Originally Posted by M_a_t_t View Post
My guess is that the air flow is so turbulent it made little/no difference.
good thought, I've been researching undertrays all morning and from the looks of it i should have started at the front of the vehicle. perhaps with some smoother airflow feeding into it it might do something
__________________

  Reply With Quote
Old 02-27-2021, 02:57 PM   #4 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 23,786
Thanks: 6,719
Thanked 7,603 Times in 6,205 Posts
Quote:
so as I suspected the gains, if any, might be too small to measure at this level with this equipment.
Never saw that one coming.
__________________
.
.

Without freedom of speech we wouldn't know who all the idiots are. -- anonymous poster
____________________

"You have died of suddenly"
Oregon Trail 2022

____________________
  Reply With Quote
Old 02-27-2021, 03:49 PM   #5 (permalink)
Master EcoModder
 
Ecky's Avatar
 
Join Date: Dec 2011
Location: New Zealand
Posts: 4,758

ND Miata - '15 Mazda MX-5 Special Package
90 day: 36.95 mpg (US)
Thanks: 2,642
Thanked 2,340 Times in 1,447 Posts
Quote:
Originally Posted by freebeard View Post
Never saw that one coming.
I can definitely appreciate the method and effort.
  Reply With Quote
The Following User Says Thank You to Ecky For This Useful Post:
freebeard (02-27-2021)
Old 02-28-2021, 02:37 PM   #6 (permalink)
マット
 
M_a_t_t's Avatar
 
Join Date: Nov 2015
Location: Indiana
Posts: 715

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 257 Times in 187 Posts
Quote:
Originally Posted by ElPants21 View Post
good thought, I've been researching undertrays all morning and from the looks of it i should have started at the front of the vehicle. perhaps with some smoother airflow feeding into it it might do something
It would probably work better starting from the front, but if you keep putting it off because it will be more complicated to work around the engine compartment (like I've been doing) then it might be better to just start somewhere even if it's at the back.

__________________
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
  Reply With Quote
Reply  Post New Thread


Tags
aero test, easy diy mods, highlander hybrid, spare tire, toyota

Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com