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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 03-26-2008, 12:48 PM   #1 (permalink)
Administrator
 
Daox's Avatar
 
Join Date: Dec 2007
Location: Germantown, WI
Posts: 11,171

CM400E - '81 Honda CM400E
90 day: 51.49 mpg (US)

Daox's Grey Prius - '04 Toyota Prius
Team Toyota
90 day: 49.53 mpg (US)

Daox's Insight - '00 Honda Insight
90 day: 64.33 mpg (US)

Swarthy - '14 Mitsubishi Mirage DE
Mitsubishi
90 day: 56.69 mpg (US)
Thanks: 2,469
Thanked 2,537 Times in 1,529 Posts
Swapping in a higher temp thermostat

So, the Paseo look like it needs a new thermostat. I went online and browsed over the selection I have. It seems the stock thermostat is set to 180°F (82°C). Now, I've heard of guys using higher temp thermostats and getting better mileage. So, I continued digging and found I can get a 192°F (89°C) thermostat for the car. Hurray. Now, why does this help? What does it hurt? OEMs must not use 192°F stock for a reason. I'm thinking it probably hurts power output as ignition timing may need to be retarded due to insufficient cooling and hotspot developing. I'm not sure why hotter would be better except that you loose less energy through your coolant system.

__________________
Current project: A better alternator delete
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 03-26-2008, 01:06 PM   #2 (permalink)
Master EcoModder
 
bhazard's Avatar
 
Join Date: Mar 2008
Location: Toledo, OH
Posts: 500

2012 Golf TDI - '12 Volkswagen Golf TDI
TEAM VW AUDI Group
90 day: 45.51 mpg (US)
Thanks: 6
Thanked 34 Times in 27 Posts
192-195 is stock on most cars Ive come across.
__________________
'05 Outback XT, 19 mpg

BP-turbo 93 Festiva (long gone)
1/4 mile - 12.50@111.5
Best MPG - 36.8
  Reply With Quote
Old 03-26-2008, 01:14 PM   #3 (permalink)
Master EcoModder
 
tasdrouille's Avatar
 
Join Date: Jan 2008
Location: Mirabel, QC
Posts: 1,672

The Guzzler - '08 Hyundai Elantra GL
90 day: 33.12 mpg (US)

Got Soul? - '11 Kia Soul 2U
Thanks: 35
Thanked 85 Times in 56 Posts
The thermostat on my 2008 starts to open at 177°F and is fully open at 201°F.
__________________



www.HyperKilometreur.com - Quand chaque goutte compte...
  Reply With Quote
Old 03-26-2008, 04:22 PM   #4 (permalink)
Liberti
 
LostCause's Avatar
 
Join Date: Feb 2008
Location: California
Posts: 504

Thunderbird - '96 Ford Thunderbird
90 day: 27.75 mpg (US)
Thanks: 0
Thanked 7 Times in 7 Posts
I also do not understand the logic behind running a higher temp. thermostat. Theoretically, wouldn't you be lowering efficiency by increasing the temp. of the cold reservoir? Then again, I'm wondering what the true cold reservoir is...the coolant or the air.

The equation I'm thinking of is the Carnot Theorem: 1 - Tc/Th

I can't really think of any benefits...

- LostCause
  Reply With Quote
Old 03-26-2008, 06:08 PM   #5 (permalink)
Pokémoderator
 
cfg83's Avatar
 
Join Date: Dec 2007
Location: Southern California
Posts: 5,864

1999 Saturn SW2 - '99 Saturn SW2 Wagon
Team Saturn
90 day: 40.49 mpg (US)
Thanks: 439
Thanked 529 Times in 356 Posts
Hello -

I am not an authority, but I have read on forums that the higher temp means that the engine is running more efficiently. The analogy would be a cold engine in the morning that does not become "efficient" until it is all warmed up.

If you are an auto manufacturer, I think that you are engineering with two goals in mind. Efficiency *and* reliability. The "balanced" response is to get the engine to be hot enough to run efficiently, but cool enough to be as far away from the "overheat zone" as possible. If you want reliability, you choose the T-Stat that gives you that compromise.

Also, you are designing the cooling system for the broad majority spectrum of drivers. Most drivers are not the "feather foots" that we are, so the cooling system needs to serve their driving habits, not ours.

As an Ecomodder, we are doing mods that "push" the engine for more fuel efficiency. As a result, we have to monitor the engine's health to a greater degree. We have to be vigilant, just like someone who puts a high-performance mod onto their car.

I have the hotter T-Stat. I used to run at about 180 degrees F. Now I run at 190 degrees F.

CarloSW2
__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote
Old 03-26-2008, 06:25 PM   #6 (permalink)
Administrator
 
Daox's Avatar
 
Join Date: Dec 2007
Location: Germantown, WI
Posts: 11,171

CM400E - '81 Honda CM400E
90 day: 51.49 mpg (US)

Daox's Grey Prius - '04 Toyota Prius
Team Toyota
90 day: 49.53 mpg (US)

Daox's Insight - '00 Honda Insight
90 day: 64.33 mpg (US)

Swarthy - '14 Mitsubishi Mirage DE
Mitsubishi
90 day: 56.69 mpg (US)
Thanks: 2,469
Thanked 2,537 Times in 1,529 Posts
You had to see this comming.

Did it make a noticable difference?
__________________
Current project: A better alternator delete
  Reply With Quote
Old 03-26-2008, 06:27 PM   #7 (permalink)
British Ecomod Hypermiler
 
AXMonster's Avatar
 
Join Date: Mar 2008
Location: South Coast, England
Posts: 101

The AXe - SOLD - '97 Citroen Citroen AX 1.1i 5 Door
90 day: 46.78 mpg (US)

Foci - '03 Ford Ford Focus Tdci Ghia Estate
90 day: 64.37 mpg (US)
Thanks: 1
Thanked 11 Times in 10 Posts
IIRC the reason for higher engine temps for economy are:

1) the higher the engine temp the lower the friction (mainly due to design clearances and pumping of fluids),
2) also the better the vapourisation of fuel prior to combustion leads to more complete combustion (a more homogenious mixture)
3) and the lower the differential between combustion flame temperature and piston/cylinder/combustion chamber temperature.

The chamber temperature is an interesting one as the heat released to the metal by the flame (and hence the loss of energy to the coolant) is actually less the higher the engine temperature. This means that more energy is available to expand the gasses in the cylinder and propel the vehicle.

Ideally the engine would run at the same temperature as the combustion flame, so there would be no heat rejection to the coolant and therefore no energy loss & perfect efficiency
__________________
1997 Citroen AX 1.1i SPI
2003 Ford Focus 1.8 Tdci estate
Ecomods: See my garage



  Reply With Quote
Old 03-26-2008, 06:44 PM   #8 (permalink)
Master EcoModder
 
tasdrouille's Avatar
 
Join Date: Jan 2008
Location: Mirabel, QC
Posts: 1,672

The Guzzler - '08 Hyundai Elantra GL
90 day: 33.12 mpg (US)

Got Soul? - '11 Kia Soul 2U
Thanks: 35
Thanked 85 Times in 56 Posts
Thermal losses accounting for roughly 65% of all the energy spent in city driving, there's a lot to gain in reducing those losses.
__________________



www.HyperKilometreur.com - Quand chaque goutte compte...
  Reply With Quote
Old 03-26-2008, 08:00 PM   #9 (permalink)
Pokémoderator
 
cfg83's Avatar
 
Join Date: Dec 2007
Location: Southern California
Posts: 5,864

1999 Saturn SW2 - '99 Saturn SW2 Wagon
Team Saturn
90 day: 40.49 mpg (US)
Thanks: 439
Thanked 529 Times in 356 Posts
Daox -

Quote:
Originally Posted by Daox View Post
You had to see this comming.

Did it make a noticable difference?
Good question. I made the switch in my early less-accurate data recording days. ... dig dig dig ... Ok, here are my gaslogs :

1999 Saturn SW2 with switch to hotter T-Stat
Code:
BEFORE            
Stock T-Stat    Miles Gal(US)      MPG
08/31/2006     192.00    4.84    39.66
09/03/2006     148.00    3.23    45.82
09/07/2006     187.00    6.53    28.63
09/10/2006     140.00    3.64    38.46
09/13/2006     170.00    4.19    40.57
09/16/2006     202.00    6.85    29.48
09/19/2006     259.00    6.94    37.31
09/22/2006     265.00    7.04    37.64
09/26/2006     288.00    7.15    40.27
09/29/2006     275.00    6.99    39.34
TOTAL         2126.00   57.40    37.04
            
AFTER            
Hotter T-Stat   Miles Gal(US)      MPG         
10/02/2006     219.00    6.90    31.73
10/07/2006     279.00    7.00    39.85
10/11/2006     274.00    7.30    37.53
10/16/2006     305.00    7.25    42.06
10/20/2006     292.00    6.00    48.66(*)
10/23/2006     187.00    6.05    30.90
10/26/2006     232.00    5.72    40.55
10/31/2006     265.00    6.25    42.40
11/02/2006     246.00    6.30    39.04
11/07/2006     260.00    6.10    42.62
TOTAL         2559.00   64.87    39.45
39.45 / 37.04 = 1.0548 => 5.5% increase in MPG.

Soooooo, it appears that I got a +5% increase in MPG. Here are my only modifications during this time :

Code:
2006/09/30 - Switched to 192-195 Coolant Thermostat (Napa Part #THM268)
2006/10/28 - Front wheel spoilers (modest aerodynamic upgrade)
(*) Now, here's the rub. On October 19, 2006, I discovered the P&G (Pulse and Glide) driving strategy. This was "mild" engine-on P&G, but my daily runs improved.

Therefore, after October 19th, I cannot say if it was the T-Stat or the modified driving style, .

CarloSW2
__________________

What's your EPA MPG? Go Here and find out!
American Solar Energy Society
  Reply With Quote
Old 03-26-2008, 08:06 PM   #10 (permalink)
EV OR DIESEL
 
Join Date: Dec 2007
Location: South Louisiana
Posts: 1,748

FarFarfrumpumpen - '03 Volkswagen Jetta Wagon GLS Premium

Quorra - '12 Tesla Model S P85
Thanks: 57
Thanked 107 Times in 83 Posts
Send a message via AIM to dremd
Efficiency improvement simple, you are wasting less heat from combustion in to the cylinder walls/ head.

+ other things.

I didn't believe it at first, but it is true.

__________________
2012 Tesla Model S P85
2013 Nissan LEAF SV totaled by now deceased intoxacated driver.
2012 Nissan LEAF SV
6 speed ALH TDI Swapped in to a 2003 Jetta Wagon
  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Engine efficiency improvement through higher temp thermostat? Lazarus General Efficiency Discussion 23 09-16-2015 02:27 AM
DIY - Thermostat Install SVOboy DIY / How-to 2 11-18-2008 03:32 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com