Welcome to the North American Subaru Impreza Owners Club Tuesday June 2, 2015
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Normally Aspirated Powertrain

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 02-28-2001, 09:19 AM   #1
KITTbri
Scooby Newbie
 
Member#: 2748
Join Date: Oct 2000
Location: Atlanta, Ga
Vehicle:
1992 WHT SE-Rw/stuff
2.5RS & '01 Mazda MP3

Question engine temp & hp

talking with a gear head friend of mine...
what about installing a lower temp thermostat and running the engine at a lower temp. somewhere around 180. or does the ej25 already run low?
* Registered users of the site do not see these ads.
KITTbri is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 02-28-2001, 09:29 AM   #2
nikkicalves
Scooby Newbie
 
Member#: 3608
Join Date: Jan 2001
Location: the T-dot - The green igloo billowing black smoke
Vehicle:
2000 Impreza
Tanned - BRP

Post

Why?? what is the reason for changing the operating temp.
nikkicalves is offline   Reply With Quote
Old 02-28-2001, 09:37 AM   #3
BongMan
Scooby Specialist
 
Member#: 2399
Join Date: Sep 2000
Location: fremont, in the bay man
Vehicle:
2001 Impreza RS
Blue

Post

yea that sounds like a good idea, i did that in my old camaro and it worked like a charm, i'm almost certain that should help cool the engine temp.

I'm gonna put in an oil cooler myself because of thouse horrific engine temps.

I'm not sure what kind of temp the car is at right now, maybe you should get some kind of gauge and hook that up to your ecu and figure it out.
good luck
larry
BongMan is offline   Reply With Quote
Old 02-28-2001, 09:38 AM   #4
DigDug
Scooby Newbie
 
Member#: 4077
Join Date: Feb 2001
Location: Eastern US
Vehicle:
1999 Impreza 2.5RS
Aspen White

Lightbulb

Usually people put in thermostats with higher temp threshold... I am not sure why you would want a lower temp one. I don't think there are gains to be had there with an EJ25, and certainly not a stock EJ25...
DigDug is offline   Reply With Quote
Old 02-28-2001, 09:40 AM   #5
DigDug
Scooby Newbie
 
Member#: 4077
Join Date: Feb 2001
Location: Eastern US
Vehicle:
1999 Impreza 2.5RS
Aspen White

Question

Horrific operating temps? Are we talking about Subaru's here? Are you running a turbo, or have you raised redline to 8K or something?
DigDug is offline   Reply With Quote
Old 02-28-2001, 09:51 AM   #6
KITTbri
Scooby Newbie
 
Member#: 2748
Join Date: Oct 2000
Location: Atlanta, Ga
Vehicle:
1992 WHT SE-Rw/stuff
2.5RS & '01 Mazda MP3

Post

from my friend:

We are talking about lowering the engine coolant temperature. It is controled by what is called a thermostat. It is a valve in the cooling system that opens and closes at a certain temperature. It has a bimetal spring that changes its tension at a certain temperature with actuates the opening and closing. These are not adjustable. If you want to change your coolant operating temp just swap thermostats.
Most emissions cars operate at either 195 F or 210 F. Older cars operated at 180 F. The 195 to 210 is for emissions reasons. 180 is ideal and any colder is non-productive. If you reduce the coolant temp then you also reduce the temp of the engine block and the engine components. When the engine draws in air it pulls it through an intake manifold and a cylinder head port before it gets to the cylinder. The heat from these components radiates into the intake air heating it up. Colder air is denser air which means more air per volume which is more fuel per volume. A 10 degree reduction in temp is probably worth a couple of horsepower.
Also hot engines tend to detonate more than cold engines. Hot spots on the cylinder head cause detonation. A cooler head helps reduce this allowing you to use lower octane gas, or raise compression with the same octane gas.

KITTbri is offline   Reply With Quote
Old 02-28-2001, 10:10 AM   #7
tmat3
Scooby Specialist
 
Member#: 2817
Join Date: Nov 2000
Location: NYC and Troy, NY
Vehicle:
2001 Impreza 2.5RS
BRP

Post

If you lower the operating temp of the engine by installing a lower-temp thermostrat, sometimes the computer thinks the engine is not hot enough and puts itself in open-loop mode. Thus, leading to poor gas mileage. I read that on http://www.2carpros.com.
tmat3 is offline   Reply With Quote
Old 02-28-2001, 10:13 AM   #8
DigDug
Scooby Newbie
 
Member#: 4077
Join Date: Feb 2001
Location: Eastern US
Vehicle:
1999 Impreza 2.5RS
Aspen White

Talking

I seem to remember ours being 180, but I could be wrong. You're just not going to get gains out of our EJ25 (stock anyways) by "upgrading" the thermostat.
DigDug is offline   Reply With Quote
Old 02-28-2001, 10:21 AM   #9
2.5GT
Scooby Specialist
 
Member#: 2697
Join Date: Oct 2000
Location: Olney, MD. Work in McLean, VA
Vehicle:
2000 Celica GT-S
Spectra Blue

Post

A couple of friends of mine swapped thermostats on their vw golfs with good results. The problem, depending on where you live, is that you may have to swap the thermostats when the ambient temperature drops. Sometimes, I was told, if the thermostat temp is too low given the outside temp, the engine will not be operating at it's optimal operating temperature which could decrease performance/longevity of the engine. But that's just what I heard.

2.5GT
2.5GT is offline   Reply With Quote
Old 02-28-2001, 10:26 AM   #10
DigDug
Scooby Newbie
 
Member#: 4077
Join Date: Feb 2001
Location: Eastern US
Vehicle:
1999 Impreza 2.5RS
Aspen White

Lightbulb

Exactly. The thermodynamic efficiency of our engine was determined at the factory, by real-life engineers. Trying to make your engine run substantially cooler than it already does (unless you are REALLY modifying the engine) is just not a good way to make power. Look into forced induction. That is the way to make power!
DigDug is offline   Reply With Quote
Old 02-28-2001, 10:31 AM   #11
jacktam1
Scooby Specialist
 
Member#: 1783
Join Date: Jul 2000
Location: Richmond,BC,Canada
Vehicle:
2000 2.5RS
silver

Post

I've the lower-temp thermostrat which is for ej20 and ej25, no problem at all for almost a year.
jacktam1 is offline   Reply With Quote
Old 02-28-2001, 10:34 AM   #12
KITTbri
Scooby Newbie
 
Member#: 2748
Join Date: Oct 2000
Location: Atlanta, Ga
Vehicle:
1992 WHT SE-Rw/stuff
2.5RS & '01 Mazda MP3

Post

jack - what about gains? notice any?
KITTbri is offline   Reply With Quote
Old 02-28-2001, 11:51 AM   #13
KITTbri
Scooby Newbie
 
Member#: 2748
Join Date: Oct 2000
Location: Atlanta, Ga
Vehicle:
1992 WHT SE-Rw/stuff
2.5RS & '01 Mazda MP3

Post

from what i understand 180 is within closed loop mode unless the ecu is uppity.
KITTbri is offline   Reply With Quote
Old 02-28-2001, 08:59 PM   #14
P.K. Motorsports
Scooby Specialist
 
Member#: 1110
Join Date: Mar 2000
Location: USA
Vehicle:
1999 RS
Silver

Post

Every Japanese car I've owned ran at 180. I have seen domestic cars running 195 and 210 though.

The only time your lower temp thermostat would make the engine run at a lower temperature would be on the freeway. In stop-and-go, at hot idle, and on the track the temperature is controlled by the fans kicking on and off. This is not a small block Chevy with a belt-driven fan - the fans only run when they are needed to reduce the temperature. By the time your fans kick on the thermostat is wide open and putting a colder one in won't make a whit of difference. Only with good airflow and moderate throttle will the thermostat engage to retain hot coolant in the block, thus maintaining engine temperature... as in on the freeway.
P.K. Motorsports is offline   Reply With Quote
Old 02-28-2001, 11:43 PM   #15
mcgyver
Scooby Newbie
 
Member#: 1655
Join Date: Jun 2000
Location: Novato, CA
Vehicle:
MY98 RS w/WRX Conv
I-Speed Tech

Exclamation

OK here's my $.02

I have a Bad head gasket on my MY98, I had a Track Day coming up on 2/23. So, I originally suspected that it was the thermostat, I replaced several with no beneficial results. It turned out to be the head gasket.

My original thermostat, the dealer replacement, and an aftermarket thermostat all were 170 degrees. Our cars run with 170 degree thermostats, you can't get much lower.

But in my quest to keep from Overheating, I found a 160 degree thermostat, which made No difference. So, to keep my car from Overheating, I removed the thermostat entirely. I made a restrictor plate with a 1/2" opening, this let the car run just warm enough. It's able to drive down the freeway and light throttle, but drive it hard and it just pushes out the coolant and begins to Overheat. My car runs on COLD and I far as can tell there is NO performance gain. It is going in this week for head gaskets, after that the experiment will end.

Just my $.02

Adam
mcgyver is offline   Reply With Quote
Old 03-01-2001, 07:10 AM   #16
svxtrem
Scooby Newbie
 
Member#: 1008
Join Date: Mar 2000
Location: Grand Forks, ND
Vehicle:
2006 STI
Steel Grey Metallic

Post

The lower temp thermostat trick works best on engines that have an intake manifold that is exposed to lots of heat. Lowering the temp of the actual heads/cylinders is not what you want. The only gains to be had is to lower the intake temp. On the subaru, the easiest way is to put a valve into the water hose that runs to the throttle body. This hot water is used to keep the throttle body from icing up in cold weather. In warm weather (or for Southern folks), you can either shut off the valve, or remove the water hose (reroute around) altogether. Don't bother fooling with the thermostat, as this mod is easier, more practical, and lowers the temp in the intake to ambient temps, rather than to 180.

svxtrem
svxtrem is offline   Reply With Quote
Old 03-01-2001, 04:10 PM   #17
WRX1
Scooby Specialist
 
Member#: 3533
Join Date: Jan 2001
Chapter/Region: MWSOC
Location: St. Paul MN, USA
Vehicle:
2002 Impreza WRX
WR Blue

Post

I don't know of anyone doing this is smaller cars, but in the domestic stuff (carmaros, mustangs, etc) I have seen and done alot of this, and it works. My buddy has a 94 Z28, and we droped in the 160 in place of the factory 195. By seat of the pants (forgot the g-tech at my house), it made a difference. Along with keeping the motor cooler for more dense air charge, it will trick the computer into think that the motor is still cold. When the motor is cold, it give is a little more gas to compensate for the dense air charge. Like I said, I don't know of anyone doing this on imports, but is does work for the bigger stuff. I even run a 170 in my PU truck in the summer for better torque (and I still get 20 mpg crusing on the freeway).
WRX1 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
FS: DEFI: Oil temp & pressure, coolant temp, EGT, Boost & Link w/ housing GC8WSI Interior/Dressup/Audio & Security 16 10-20-2008 10:16 PM
defi water temp & oil temp - suggestions/help on install please BeeSTi Electrical & Lighting 2 12-05-2005 06:39 AM
Temp gauge on cluster... is that oil or engine temp? gopsu Newbies & FAQs 1 10-02-2005 10:45 PM
FS: Autometer Guages Oil Temp & Press & A/F mixture cjfike Private 'For Sale' Classifieds 2 04-14-2005 09:33 PM
Cooler engine temps = engine not blowing up? CynicX Factory 2.0L Turbo Powertrain (EJ Series Factory 2.0L Turbo) 4 11-20-2003 09:07 PM


All times are GMT -4. The time now is 11:02 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2015 Axivo Inc.
Copyright ©1999 - 2015, North American Subaru Impreza Owners Club, Inc.