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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 11-14-2012, 07:25 AM   #1 (permalink)
Master Ecomadman
 
arcosine's Avatar
 
Join Date: Nov 2010
Location: Chicago area
Posts: 1,149

sc1 - '98 saturn sc1
Team Saturn
90 day: 43.17 mpg (US)

Airplane Bike - '11 home built Carp line Tour

rans - '97 rans tailwind

tractor - '66 International Cub cadet 129

2002 Space Odyssey - '02 Honda Odyssey EX-L
90 day: 28.25 mpg (US)

red bug - '00 VW beetle TDI

big tractor - '66 ford 3400

red vw - '00 VW new beetle TDI
90 day: 58.42 mpg (US)

RV - '88 Winnebago LeSharo
90 day: 16.67 mpg (US)
Thanks: 20
Thanked 333 Times in 225 Posts
Engine Compartment Venting

Hi,

Currently, I am venting the engine compartment through gill slot openings in the belly pan. This is making lot of turbulence under the car, it's like having a window open. I am considering venting though the front wheel wells, where the air is already disturbed. Anybody have any thoughts or comments on engine compartment venting?

__________________
- Tony

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 11-14-2012, 11:03 AM   #2 (permalink)
Aero Wannabe
 
COcyclist's Avatar
 
Join Date: Dec 2007
Location: NW Colo
Posts: 738

TDi - '04 VW Golf
TEAM VW AUDI Group
90 day: 53.2 mpg (US)
Thanks: 705
Thanked 218 Times in 169 Posts
Quote:
Originally Posted by arcosine View Post
Hi,

Currently, I am venting the engine compartment through gill slot openings in the belly pan. This is making lot of turbulence under the car, it's like having a window open. I am considering venting though the front wheel wells, where the air is already disturbed. Anybody have any thoughts or comments on engine compartment venting?
This is what has been done on the Aerocivic and on my own car with a full, front to back belly pan. The openings in the wheelwells are plenty large enough to let the air escape. Most of us on this forum already have some of the grill blocked so there is minimal cooling air going through the engine compartment. Watch your ScanGuage. I think you'll be fine.
__________________
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
Old 11-14-2012, 04:39 PM   #3 (permalink)
Master EcoModder
 
Join Date: Oct 2008
Location: Mid-Atlantic
Posts: 491

OurInsight - '06 Honda Insight
Thanks: 170
Thanked 69 Times in 44 Posts
According to Hucho, the very best arrangement is to vent into the area on top of the hood. Venting into the wheel wells and into the underneath are equal and are half as good Cd wise, according to his book.
  Reply With Quote
Old 11-14-2012, 05:06 PM   #4 (permalink)
Master EcoModder
 
Join Date: Jan 2012
Location: United States
Posts: 1,756

spyder2 - '00 Toyota MR2 Spyder
Thanks: 104
Thanked 407 Times in 312 Posts
Quote:
Originally Posted by jime57 View Post
According to Hucho, the very best arrangement is to vent into the area on top of the hood. Venting into the wheel wells and into the underneath are equal and are half as good Cd wise, according to his book.
I think that would vary quite a bit from car to car no? Wheel wells have different designs, underbodies have different designs (or lack thereof), and hoods have different angles and shapes.

Venting under the car could be marginally better if there's one of those higher diffusers.
  Reply With Quote
Old 11-14-2012, 06:30 PM   #5 (permalink)
EcoModding Lurker
 
Join Date: Oct 2012
Location: muskoka
Posts: 81

Speedy Gonzales - '11 Ford Fiesta SES
Thanks: 7
Thanked 11 Times in 7 Posts
Pull out the seal for the hood at the base of the windshield...
__________________

  Reply With Quote
Old 11-14-2012, 08:25 PM   #6 (permalink)
Master Ecomadman
 
arcosine's Avatar
 
Join Date: Nov 2010
Location: Chicago area
Posts: 1,149

sc1 - '98 saturn sc1
Team Saturn
90 day: 43.17 mpg (US)

Airplane Bike - '11 home built Carp line Tour

rans - '97 rans tailwind

tractor - '66 International Cub cadet 129

2002 Space Odyssey - '02 Honda Odyssey EX-L
90 day: 28.25 mpg (US)

red bug - '00 VW beetle TDI

big tractor - '66 ford 3400

red vw - '00 VW new beetle TDI
90 day: 58.42 mpg (US)

RV - '88 Winnebago LeSharo
90 day: 16.67 mpg (US)
Thanks: 20
Thanked 333 Times in 225 Posts
Venting on top would put a lot of dirty air over the car body. Im going to try venting into the wheel wells and close off the openings in the under body belly pan and shoot a tuft video again.
__________________
- Tony

  Reply With Quote
Old 11-14-2012, 08:46 PM   #7 (permalink)
Master EcoModder
 
Join Date: Oct 2008
Location: Mid-Atlantic
Posts: 491

OurInsight - '06 Honda Insight
Thanks: 170
Thanked 69 Times in 44 Posts
Quote:
Originally Posted by serialk11r View Post
I think that would vary quite a bit from car to car no? Wheel wells have different designs, underbodies have different designs (or lack thereof), and hoods have different angles and shapes.
You may think what you like, as may I, as may any of us. I'm only reporting from a reliable handbook on the subject. The original paper is: BUCHHEIM, R., DEUTENBACH, L.-R., LUCKOFF, H.-J., "Necessity and Premises for Reducing the Aerodynamic Drag of future Passenger Cars," SAE Paper No. 810185, Society of Automotive Engineers, Warrendale, Pa., 1981.

Quote:
Venting under the car could be marginally better if there's one of those higher diffusers.
Reference please
  Reply With Quote
Old 11-15-2012, 11:17 AM   #8 (permalink)
Aero Wannabe
 
COcyclist's Avatar
 
Join Date: Dec 2007
Location: NW Colo
Posts: 738

TDi - '04 VW Golf
TEAM VW AUDI Group
90 day: 53.2 mpg (US)
Thanks: 705
Thanked 218 Times in 169 Posts
Quote:
Originally Posted by arcosine View Post
Venting on top would put a lot of dirty air over the car body.
There are some ultra high performance cars that vent radiator air over the hood for better aerodynamics. One possible downside for production cars is the chance of coating your windshield with glycol while driving, if there is any sort of cooling system failure. Also, high performance cars are designed to be driven with big engines and pedal to the floor, generating much more waste heat than your average hypermiler. IMHO if you are already using some sort of grill blocking we are splitting hairs here. Try sealing the underbody and monitor your engine temperature.
__________________
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
Old 11-15-2012, 12:21 PM   #9 (permalink)
Master Ecomadman
 
arcosine's Avatar
 
Join Date: Nov 2010
Location: Chicago area
Posts: 1,149

sc1 - '98 saturn sc1
Team Saturn
90 day: 43.17 mpg (US)

Airplane Bike - '11 home built Carp line Tour

rans - '97 rans tailwind

tractor - '66 International Cub cadet 129

2002 Space Odyssey - '02 Honda Odyssey EX-L
90 day: 28.25 mpg (US)

red bug - '00 VW beetle TDI

big tractor - '66 ford 3400

red vw - '00 VW new beetle TDI
90 day: 58.42 mpg (US)

RV - '88 Winnebago LeSharo
90 day: 16.67 mpg (US)
Thanks: 20
Thanked 333 Times in 225 Posts
Quote:
imho if you are already using some sort of grill blocking we are splitting hairs here. Try sealing the underbody and monitor your engine temperature.
]

it is sealed, read the first post!
__________________
- Tony

  Reply With Quote
Old 11-15-2012, 02:06 PM   #10 (permalink)
DieselMiser
 
ConnClark's Avatar
 
Join Date: Jun 2008
Location: Richland,WA
Posts: 985

Das Schlepper Frog - '85 Mercedes Benz 300SD
90 day: 23.23 mpg (US)

Gentoo320 - '04 Mercedes C320 4Matic
90 day: 22.44 mpg (US)
Thanks: 46
Thanked 231 Times in 160 Posts
Try reading this paper "Interference Effects of Cooling Air-Flows with External Aerodynamics" . It covers how engine compartment cooling effects overall drag.

http://tech.jsae.or.jp/ijae/download...x?pno=20114635

Edit: I think you want to keep your under tray gill slits

__________________

Last edited by ConnClark; 11-15-2012 at 02:14 PM..
  Reply With Quote
The Following User Says Thank You to ConnClark For This Useful Post:
freebeard (11-17-2012)
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