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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 09-23-2010, 08:03 PM   #11 (permalink)
Basjoos Wannabe
 
ShadeTreeMech's Avatar
 
Join Date: Apr 2009
Location: Arkansas
Posts: 870

The Van - '97 Mercury Villager gs
90 day: 19.8 mpg (US)

Lyle the Kindly Viking - '99 Volvo V70
90 day: 25.82 mpg (US)
Thanks: 174
Thanked 49 Times in 32 Posts
Which is kinda along my train of thought. Block the grill off completely, leave an opening under the bumper for the air draw as needed by the radiator fan, and enjoy the MPG savings, intead of worrying about controlling the variable air flow from the front of the car.

The Honda CRX Del Sol had a very small grille opening under the bumper. What if it had no grille opening and just pulled in air as needed with the rad fan?

__________________
RIP Maxima 1997-2012


Quote:
Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 09-23-2010, 08:04 PM   #12 (permalink)
Basjoos Wannabe
 
ShadeTreeMech's Avatar
 
Join Date: Apr 2009
Location: Arkansas
Posts: 870

The Van - '97 Mercury Villager gs
90 day: 19.8 mpg (US)

Lyle the Kindly Viking - '99 Volvo V70
90 day: 25.82 mpg (US)
Thanks: 174
Thanked 49 Times in 32 Posts
Quote:
Originally Posted by talldudenumber5 View Post
we will have to compare grill blocks once we both finish. same car, similar driving environment. let the testing begin lol
Don't forget to put your numbers in, hard to compare when there are so few entries in your log
__________________
RIP Maxima 1997-2012


Quote:
Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
  Reply With Quote
Old 09-23-2010, 09:27 PM   #13 (permalink)
Wiki Mod
 
Weather Spotter's Avatar
 
Join Date: Nov 2009
Location: Midland MI, USA
Posts: 2,042

Max - '14 Ford C-Max SEL
Thanks: 228
Thanked 304 Times in 210 Posts
I like your questions

I did a full upper grill block, and have a lower one that can open and close as I want it . This is the best of both worlds, I can block the grill at start up or when ever I do not need the cooling. Just before the fan comes on I open the lower grill and take the aero drop instead of using the fan.
__________________
  Reply With Quote
Old 09-23-2010, 09:32 PM   #14 (permalink)
Left Lane Ecodriver
 
RobertSmalls's Avatar
 
Join Date: Aug 2008
Location: Buffalo, NY, USA
Posts: 2,257

Prius C - '12 Toyota Prius C
Thanks: 79
Thanked 286 Times in 199 Posts
ShadeTreeMech: An alternator is about 50% efficient, so if your fan draws 20A (275W), that's a 550W accessory load. You can use the calculator to turn it into a percentage if you like.

You definitely don't want the fan running ALL the time, because it is a pretty big draw.
  Reply With Quote
Old 09-23-2010, 09:53 PM   #15 (permalink)
EcoModding Lurker
 
Join Date: Aug 2010
Location: New Mexico
Posts: 41
Thanks: 3
Thanked 3 Times in 3 Posts
Well the aero drag for any of these solutions is the "sinking drag" which is equal to d(mV)/dt

mass (m in slugs) is the mass of air you're bringing up to speed of car (V - ft/sec) either passively or using the fan .... so you have the area (of your grill or opening) you have your speed (mph) and you have the density of the air P/RT (slug / ft^3) ... do the calc and you get in units slugs ft/sec^2 which is lbf ... that's your sinking drag required to cool engine.

So you block off the grill and let the fan suck it in (not too efficient at sucking these fans not designed for that) but it still wants the same heat transfer (mass flow) to cool the engine... but now instead of doing it passively you want to use electricity (juice) to get the job done. Not much sense in my opinion... I agree... take the aero hit instead.

The problem is not when you're cruising down the highway letting the good times roll though... the problem is when you're stuck in traffic in 100 deg heat going nowhere fast and the fan can't suck/push enough mass through the heat exchanger.

A variable area grill block seems like a good idea albeit an engineering problem... Personally I've got a permanent full upper grill block on (those are just for style mostly anyway) No discernible negative effect so far... and this winter I hope to see what a partial lower block can do...

This is one aspect the EV's definitely have going for them.
  Reply With Quote
Old 09-23-2010, 10:07 PM   #16 (permalink)
EcoModding Lurker
 
Join Date: Aug 2010
Location: New Mexico
Posts: 41
Thanks: 3
Thanked 3 Times in 3 Posts
Quote:
Originally Posted by Weather Spotter View Post
I like your questions

I did a full upper grill block, and have a lower one that can open and close as I want it . This is the best of both worlds, I can block the grill at start up or when ever I do not need the cooling. Just before the fan comes on I open the lower grill and take the aero drop instead of using the fan.

Nice... is that thermostat controlled? or do you need to remember to open it... the latter not something I'd trust the wife with.
  Reply With Quote
Old 09-23-2010, 11:19 PM   #17 (permalink)
Master EcoModder
 
Join Date: Jan 2009
Location: Maui, Hawaii
Posts: 813
Thanks: 5
Thanked 34 Times in 26 Posts
Quote:
Originally Posted by ShadeTreeMech View Post
Which is kinda along my train of thought. Block the grill off completely, leave an opening under the bumper for the air draw as needed by the radiator fan, and enjoy the MPG savings, intead of worrying about controlling the variable air flow from the front of the car.

The Honda CRX Del Sol had a very small grille opening under the bumper. What if it had no grille opening and just pulled in air as needed with the rad fan?
Well it needs some opening to pull air in. The smaller the opening, the less efficient the fan is, and you can increase fan power without pulling in much more air.
  Reply With Quote
Old 09-24-2010, 11:44 AM   #18 (permalink)
EcoModding Apprentice
 
Join Date: Jul 2009
Location: Live in Tucson AZ, work and car now in Detroit
Posts: 200

Protege - '97 Mazda Protege DX
90 day: 46.42 mpg (US)
Thanks: 13
Thanked 23 Times in 18 Posts
I blocked about 75% of my grill. Also ran an LED light on the dash to see when the fan cut on. On an 80 degree day, cruising at 55, the fan will cut on for a minute every 4-5 minutes. That seems reasonable to me. Not too many days over 80 here in San Jose CA. Then last night (around 60 outside) it only came on near home when I EOC'd into a light and then restarted when light turned green. Fan came on for 30 seconds on engine restart.
I also took the snorkle off the air intake so I am pulling air from about a foot behind the radiator fan. When the radiator fan is running I can get air temps of 90-100. When the fan is off then the air temps are only 5 or 10 degrees above the outside temp. This data is making me think about at better belly pan/more sealing around hood/lights. I would like to get the air intake temps up a little more before we head into those "brutal" winters here in the bay.
  Reply With Quote
Old 09-24-2010, 11:53 AM   #19 (permalink)
Wiki Mod
 
Weather Spotter's Avatar
 
Join Date: Nov 2009
Location: Midland MI, USA
Posts: 2,042

Max - '14 Ford C-Max SEL
Thanks: 228
Thanked 304 Times in 210 Posts
Quote:
Originally Posted by nmgolfer View Post
Nice... is that thermostat controlled? or do you need to remember to open it... the latter not something I'd trust the wife with.
No it is not automatic. If you want to make it wife proof, then you would need to automate it. Doax did that with his, check his thread out for how he did it.
__________________
  Reply With Quote
Old 09-24-2010, 11:57 AM   #20 (permalink)
EcoModding Lurker
 
Join Date: Apr 2010
Location: jefferson city, mo
Posts: 60

klr 650 - '08 kawasaki klr 650

The van - '15 Dodge Grand caravan Avp
Thanks: 2
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by ShadeTreeMech View Post
Which is kinda along my train of thought. Block the grill off completely, leave an opening under the bumper for the air draw as needed by the radiator fan, and enjoy the MPG savings, intead of worrying about controlling the variable air flow from the front of the car.

The Honda CRX Del Sol had a very small grille opening under the bumper. What if it had no grille opening and just pulled in air as needed with the rad fan?
in my max i have no opening under the radiator ( under belly pan) so that would not work for me i plan to block half of both the lower openings and go from there. lol i was thinking another advantage to an upper grill block is you could paint on a grill from another company( ie BMW split grill) thought it would be funny now to convince my wife to paint it on

i really did not like the log on here to track mpg so i use a program on my wife's ipod
here are my results from may till now these are full tanks
may 13 20.8
may 24 23.8
jun 11 20.1
jun 27 21.9
jul 7 22.6
jul 29 21.8
aug 13 23.3 ( started hypermiling practice again)
aug 23 30.4 (upper grill block and mud flap deletes, mostly highway)
aug 25 24.9 (back to the city)
sep9 27.1 (461 miles ,half tank in branson, half tank highway)

__________________
SCANGUAGE IT REALLY WORKS
  Reply With Quote
The Following User Says Thank You to talldudenumber5 For This Useful Post:
ShadeTreeMech (09-24-2010)
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
First 55+ mpg tank for my '08 Cobalt XFE Fr3AkAzOiD Success Stories 36 11-13-2010 10:27 PM
MPG Baseline for Insight 1 Nailed-Long! jime57 Aerodynamics 1 07-24-2010 10:35 PM
Honda panicking about MPG? Mods current Accord to boost city & hwy MPG. MetroMPG EcoModding Central 15 07-08-2010 04:07 PM
Does this steal MPG? RandomFact314 General Efficiency Discussion 23 05-05-2009 08:08 AM
Keep A/C from running when you don't need it. TeamCF EcoModding Central 13 04-06-2009 12:55 PM



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