Aerocivic - how to drop your Cd from 0.31 to 0.17

[NeilBlanchard]

Hi,

The instructions for measuring the drag of your car doesn't seem to take account of the air temperature -- does this matter?

[MetroMPG]

Air temperature and pressure do have some effect on drag. You can get an idea of the magnitude of the differences from the aero/rolling resistance calculator tool.

Mike: the continued evolution makes the car eligible for next month's Modification of the Month contest.

[TestDrive]

Are those mini-boattails on the clearance lights?

[Cd]

Originally Posted by basjoos

Added another minor aero tweak. I took a page out of Aptera's book and installed ducts to exhaust my cabin air into the small low pressure eddy behind the license plate. I doubt I will notice any difference in mileage, but every little bit helps and it should help to move the cabin air with less fan assist.
Vent holes at back of cargo area.

I was wondering when you were going to do that sort of modification.

If I ever get around to building an EV, I plan to have dryer ducting that goes from my 'grille' to the back end of the car using the ICE exaust channel.
Hopefully this would create a 'ram-air' sort of effect to help fill in the wake around the rear plate.
I'm sure there is a way that you could come up with something similar.
Do you think something like that would even be worth it though ?

[basjoos]

Originally Posted by TestDrive

Are those mini-boattails on the clearance lights?

The clearance lights are faired on their leading and trailing ends. Every little bit of drag reduction helps.

[rkcarguy]

Basjoos,

I've noticed another member following in your footsteps and I have a question regarding your engines. Both of you started with CX models implying the 8 valve non-Vtec-E engine. Have you swapped the engine to a different one... VTEC-E ?
I owned a CX for awhile, and I got about 42 mpg on flat runs down I-5 and around 33-36 over mountain passes. I have never owned a VTEC-E engined car but they are rated higher mpg than the CX.
If you are not running the lean burn technology, I think there is more yet to be gained over your accomplishments utilizing it + starting with a CRX chassis instead of the EG hatchback.
I am working with autocad attempting to design a rear engined aluminum unibody aero car based on civic parts. I imported engines from Japan as a business several years ago and found several options we don't have in the USA, like the 3-stage VTEC
D15B and the Civic EL engine which is a 70HP 16V 1.3L D13B offered in the 96-98 hatchback in Japan.

[basjoos]

The current engine in my car is the 102hp engine from the DX. When it wears out, I plan to install the D15Z1 engine used in the VX, which should greatly improve my highway mileage since, with my car's low drag, I could remain in lean burn on a flat road up to 90mph.

[Piwoslaw]

rkcarguy: Basjoos wouldn't benefit much from any engine swap since he hardly uses it

[rkcarguy]

Originally Posted by Piwoslaw

rkcarguy: Basjoos wouldn't benefit much from any engine swap since he hardly uses it

I disagree. Especially if he switched to the 3-stage VTEC which has lean burn and also 130HP hi-cam, he could see better MPG-over 10%+ possibly, and have more power on tap if you want it.
At a 95mpg best without a VTEC-E, a lean burn engine could push this car into the record books.

[KJSatz]

I believe he's in this for savings and wants any additions to pay for themselves in short order, and that's why he isn't planning on getting a lean-burn engine until his current one gives out.