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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 10-14-2017, 08:39 PM   #1 (permalink)
Master EcoModder
 
Join Date: Jul 2017
Location: Memphis, Tn
Posts: 463
Thanks: 320
Thanked 107 Times in 81 Posts
I'm thinking about lowering my Civic

I am thinking about lowering my Civic about 2-3 inches with lowering springs. How much would and why would lowering affect my Cd? It would probably not affect it much, if at all, but I am an idiot when it comes to aerodynamics, so I don't know. My 2005 Civic gets around 30 MPG highway. If I lower it, could I get 31 MPG highway? Thanks.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 10-14-2017, 11:53 PM   #2 (permalink)
Master EcoModder
 
Stubby79's Avatar
 
Join Date: Sep 2012
Location: Victoria, BC
Posts: 1,747

Firefly EV - '98 Pontiac Firefly EV
90 day: 107.65 mpg (US)

Little Boy Blue - '05 Toyota Echo
90 day: 33.35 mpg (US)

BlueZ - '19 Nissan 370Z Sport
90 day: 17.19 mpg (US)
Thanks: 75
Thanked 576 Times in 426 Posts
MetroMPG appeared to have success with a ~3 MPG gain when he lowered his Firefly:
http://ecomodder.com/forum/showthrea...s-35164-5.html

But no promises. You've a completely different car.

If saving $$ is your goal, you will probably have to own it a loooong time in order to offset the cost of lowering it. Especially if someone else does the install, and if you go for an alignment after.
  Reply With Quote
Old 10-15-2017, 02:27 AM   #3 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

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: 1,585
Thanked 3,555 Times in 2,218 Posts
I secured a free set of junkyard springs for my 'Coupe and cut them myself, keeping the originals in case it was a fail. I align my vehicles in the driveway myself then get them "officially" checked at shops that offer free alignment checks; they've always been spot-on. So the cost of this mod for me has been nearly zero dollars; some gas for parts running plus my time and effort.

I am pleased with the look, ride (somewhat stiffer) and handling (corners better) of the lowered car. My mpg records and the ever-changing nature of my trips make it difficult if not impossible to make any fe claims for this mod. However it is indisputable that frontal area has been reduced a skosh.
__________________


  Reply With Quote
The Following 2 Users Say Thank You to Frank Lee For This Useful Post:
aerohead (10-21-2017), freebeard (10-16-2017)
Old 10-15-2017, 07:51 AM   #4 (permalink)
wdb
lurker's apprentice
 
Join Date: May 2008
Location: the Perimeter
Posts: 942

PlainJane - '12 Toyota Tacoma Base 4WD Access Cab
90 day: 20.98 mpg (US)
Thanks: 504
Thanked 226 Times in 173 Posts
Quote:
Originally Posted by Frank Lee View Post
frontal area has been reduced a skosh.
Can you put that in layman's terms for those of us less technically savvy?
  Reply With Quote
Old 10-15-2017, 03:37 PM   #5 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

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: 1,585
Thanked 3,555 Times in 2,218 Posts
I'll try... I found out how what appears to be a nice level spot on a concrete slab isn't. By that I mean you can't do before/after lowering measurements from, say, the bumper to the slab and get a decently accurate value; those slabs are wavy. You have to measure from, say, the top of the tire to the fenderwell or some such.

IIRC I lowered it 2" so basically 2 x (tire width in inches x 2) /144 = Af reduction in sq. ft. There may be some additional reduction via the better tucked-in lower control arms too but I haven't looked at that recently.

Incidentally I lowered the car about 14 years ago and kept it that way. It got all new struts at the same time as the cut springs. I did experiment with different front roll bar strengths/thicknesses (I have three of the common ones) and decided to stay with the stock one as I couldn't discern any cornering improvement with the strongest bar but it did induce more ride chop. I installed the softest bar in a 4-door a/t Tempo and 14" wheels (softer bar than stock and larger tires than stock) and that one rides like a Cadillac.

P.S. The new struts were stock-type replacements. They've held up and work just fine.
__________________



Last edited by Frank Lee; 10-17-2017 at 09:35 AM..
  Reply With Quote
The Following User Says Thank You to Frank Lee For This Useful Post:
aerohead (10-21-2017)
Old 10-15-2017, 04:16 PM   #6 (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 2,172 Times in 1,469 Posts
Don't lower it more than one or 2 inches. You'll regret that as you go over bumps. A very small air dam in addition to the lowering would help you, most likely.
__________________
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
Old 10-15-2017, 06:18 PM   #7 (permalink)
EcoModding Lurker
 
Join Date: Dec 2008
Location: Western Canada
Posts: 46

2015 WRX - '15 Subaru WRX
90 day: 30.63 mpg (US)

2008 Suzuki SV650SA - '08 Suzuki SV650SA
90 day: 60.81 mpg (US)
Thanks: 1
Thanked 11 Times in 10 Posts
Quote:
Originally Posted by California98Civic View Post
Don't lower it more than one or 2 inches. You'll regret that as you go over bumps. A very small air dam in addition to the lowering would help you, most likely.
Agreed. Also, I'm not sure how the suspension geometry and adjustment ability is on those cars, but usually lowering springs will increase negative camber. If you don't have any camber adjustment available on the OEM suspension, and you lower it too much, you'll have too much negative camber, which will increase wear on the inside edge of your tires. It will also reduce traction and braking grip (but may increase cornering grip if it's not too extreme). You'll probably need to buy camber plates if you lower it a lot, which will enable you to adjust the camber.

Your stock shocks will probably be outside of their ideal movement range as well, increasing the wear on the shocks if you go too low.

The new springs will need to be significantly stiffer than the stock springs so that you're not hitting the bump stops. The lower you go, the stiffer they'll need to be.
__________________

  Reply With Quote
The Following User Says Thank You to twj347 For This Useful Post:
aerohead (10-21-2017)
Old 10-16-2017, 01:33 PM   #8 (permalink)
Got MPG?
 
Join Date: Sep 2010
Location: Southern Alberta, Canada
Posts: 330

The Car - '09 Toyota Corolla CE Enhanced
Thanks: 13
Thanked 43 Times in 38 Posts
I have read that cutting springs is not a recommended practice. The spring rate/handling as well as the metals' tempering may be adversely be affected beyond what the manufactures had designed.
__________________
2013 Honda Civic Si - 2.4L
OEM front to back belly pan from the factory.
  Reply With Quote
The Following User Says Thank You to LeanBurn For This Useful Post:
aerohead (10-21-2017)
Old 10-16-2017, 03:35 PM   #9 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 27,562
Thanks: 7,738
Thanked 8,554 Times in 7,041 Posts
31mpg? Yes, if only by confirmation bias.

Assuming you stick to paved roads, the lower limit is set by speed bumps and the curb cuts to where they sell cheap gas. It triggers cRIPPLErOOSTER{sp} when people slow down for speed bumps. ...so, watch out.

There are certainly other benefits. If you only lower the front you have a better view.

Further to Frank Lee and twj347's comments: I have Macpherson struts but rear wheel drive on the Superbeetle (so YMMV), but I tried adjustable struts with stock spring rate and stiff as a Cockford Ollie. I combined lowered suspension with 50-series tires in the stock width. And a stress bar:



With the stiff springs if I drove with my elbow on the arm rest in 15 miles my collarbone would start to complain. Reverting to stock rate again ($$$) and the only downside is excessive body roll on those two lane left-turn freeway onramps and ground strikes on the edge of bridges on the Interstate.

To quote the skateboarders, "Let it grind".
  Reply With Quote
Old 10-16-2017, 10:18 PM   #10 (permalink)
Master EcoModder
 
oldtamiyaphile's Avatar
 
Join Date: May 2009
Location: Australia
Posts: 1,510

UFI - '12 Fiat 500 Twinair
Team Turbocharged!
90 day: 40.3 mpg (US)

Jeep - '05 Jeep Wrangler Renegade
90 day: 18.09 mpg (US)

R32 - '89 Nissan Skyline

STiG - '16 Renault Trafic 140dCi Energy
90 day: 30.12 mpg (US)

Prius - '05 Toyota Prius
Team Toyota
90 day: 50.25 mpg (US)

Premodded - '49 Ford Freighter
90 day: 13.48 mpg (US)

F-117 - '10 Proton Arena GLSi
Pickups
Mitsubishi
90 day: 37.82 mpg (US)

Ralica - '85 Toyota Celica ST
90 day: 25.23 mpg (US)

Sx4 - '07 Suzuki Sx4
90 day: 32.21 mpg (US)

F-117 (2) - '03 Citroen Xsara VTS
90 day: 30.06 mpg (US)
Thanks: 325
Thanked 452 Times in 319 Posts
Quote:
Originally Posted by Frank Lee View Post
I secured a free set of junkyard springs for my 'Coupe and cut them myself, keeping the originals in case it was a fail. I align my vehicles in the driveway myself then get them "officially" checked at shops that offer free alignment checks; they've always been spot-on. So the cost of this mod for me has been nearly zero dollars; some gas for parts running plus my time and effort.
As a skeptic of DIY alignments, I just tried it for the first time. It's not that difficult after all - the real time lasers make it quicker - not necessarily more accurate. I used a set square and digital level to check camber and set squares/ tape measures on the ground.

Are you using tape measures or string and axle stands or?

__________________






  Reply With Quote
Reply  Post New Thread


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