• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

what degree thermostat to use? 195* or 180* please help

  • Thread starter Thread starter 88GTMustang
  • Start date Start date Aug 20, 2007

88GTMustang

New Member
Oct 31, 2003
247
0
0
LA california
Aug 20, 2007
#1
  • Aug 20, 2007
  • #1
what would be better to use the 180 or 195. the stock one is at 195 and i heard its better to run a little bit cooler? what do you think? gt40p heads and e cam other than that stock.
 

bill302

Active Member
Nov 2, 2005
2,131
1
46
alabama,gadsden
Aug 20, 2007
#2
  • Aug 20, 2007
  • #2
180* mr. gasket ar stant super stat thermostat are my reccomendations...
 

NKau

Founding Member
Dec 15, 2001
1,346
0
37
Jefferson, WI
Aug 20, 2007
#3
  • Aug 20, 2007
  • #3
I run a 192 degree thermo, because supposedly the engine operates at better VE running at this temp, and I believe that's what the EEC-IV computer expects to see.
 

Mustang5L5

That is…until I whipped out my Bissell
Mod Dude
Feb 18, 2001
43,260
17,945
224
Massachusetts
Aug 20, 2007
#4
  • Aug 20, 2007
  • #4
Fuel injected engines run better hot.

I run a 180, but i would never go colder than that. Next time around, i'll stick with the stock t-stat
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Aug 20, 2007
#5
  • Aug 20, 2007
  • #5
Don't bother with worrying about the rating as much as the target temp. Some guys run a 160* stat and operate at 210*F. Others run a 195* stat and run right at 195*.

Use what works best for your combo. Were it me and I was where you live (LA), I'd go for the 180*. But if you have a very adequate cooling system, the 195 is cool (optimal coolant temps are said to be 190-210*F).

Good luck.
 
Reactions: mattys91gt
8

86bluecobra

Advanced Member
Dec 20, 2004
4,265
12
69
B.C. Canada
Aug 20, 2007
#6
  • Aug 20, 2007
  • #6
I run a 180 degree but I doubt you can go wrong with either.
 

Fett

New Member
Nov 2, 2004
766
6
0
Aug 20, 2007
#7
  • Aug 20, 2007
  • #7
I run 180*, but I live in South Florida.
 
S

Sicarius428

Active Member
Jan 6, 2004
2,085
5
49
Aug 20, 2007
#8
  • Aug 20, 2007
  • #8
I run a 180. The higher ones are really for emissions I believe.
Kevin
 

302RollinHard

New Member
Sep 26, 2005
0
0
0
Columbus, OH
Aug 20, 2007
#9
  • Aug 20, 2007
  • #9
it does no good to run a cooler thermostat if your cooling system can't reject enough heat to reach target temperature. I say buy a good quality 192-195* stat.
 

Fett

New Member
Nov 2, 2004
766
6
0
Aug 20, 2007
#10
  • Aug 20, 2007
  • #10
When I first installed my 180* thermostat, my car ran slightly cooler. It normally ran just above the midway point on the gauge, after the 180* stat, it ran just slightly below the midway point.

Of course this is with the stock gauge, so take it with a grain of salt.
 

twistedwankel

Member
Sep 7, 2006
200
0
17
Spring Hill, FL
Aug 22, 2007
#11
  • Aug 22, 2007
  • #11
An old racer's trick in stock class is to use the 180F or lower to fool the computer into thinking it's still cold and run a bit richer for slightly more performance.

(You can get a better constant rich condition by simply unplugging the O2 Sensor wire for short drag race runs. It takes 5 minutes from cold start for an O2 sensor to "lightoff" and affect the mixture to lean anyhow in a normal engine.)

A. You will get lower gas mileage slightly but better WOT performance.

B. This might cause you some issues during an emissions test requiring a fully hot engine? So you should change it back to 195F before your test.

C. Either 180 or 195F both work well. So depends on if you live in an emissions State or not?
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Aug 22, 2007
#12
  • Aug 22, 2007
  • #12
HEGO's light off in 30-120 seconds. That's the whole point. It can take EGO's factors longer.

O2 readings are largely ignored at WOT so I dont understand that argument.

FWIW, the engine can go lean at around 170*F at the ECT because the EEC wants it to warm up just a bit more.
 

LtDavis

20+ Year Stangneter
Nov 19, 2004
75
2
19
Raleigh, NC
Aug 22, 2007
#13
  • Aug 22, 2007
  • #13
if you trick the computer and make the engine run richer... won't that reduce performance??
 

twistedwankel

Member
Sep 7, 2006
200
0
17
Spring Hill, FL
Aug 23, 2007
#14
  • Aug 23, 2007
  • #14
LtDavis said:
if you trick the computer and make the engine run richer... won't that reduce performance??
Click to expand...

Normally one advances the base timing up to 3 degrees to utilize the richer mixture and still not activate a knock sensor. Agree lean is fast but also can create alot of heat and damage. I prefer to err on the conservative side myself. It's not awe inspiring but a few 1/100's of a second in a stock class is winning vs. who finished 2nd?
 

302RollinHard

New Member
Sep 26, 2005
0
0
0
Columbus, OH
Aug 23, 2007
#15
  • Aug 23, 2007
  • #15
We ain't got no STEEEEENKING knock sensors...............mang
 

vristang

15 Year Member
Mar 31, 2005
4,933
101
124
Seattle
Aug 23, 2007
#16
  • Aug 23, 2007
  • #16
twistedwankel said:
An old racer's trick in stock class is to use the 180F or lower to fool the computer into thinking it's still cold and run a bit richer for slightly more performance.

(You can get a better constant rich condition by simply unplugging the O2 Sensor wire for short drag race runs. It takes 5 minutes from cold start for an O2 sensor to "lightoff" and affect the mixture to lean anyhow in a normal engine.)

A. You will get lower gas mileage slightly but better WOT performance.

B. This might cause you some issues during an emissions test requiring a fully hot engine? So you should change it back to 195F before your test. (Or just unplug the O2 wire.)

C. Either 180 or 195F both work well. So depends on if you live in an emissions State or not?
Click to expand...

As JT said, HEGO's kick off pretty quick...
A. Yes, you will lose mpg, However... there is no guarantee you will gain performance by removing the O2's. I would say 50/50 on gain power/lose power.

B. I doubt you will pass emissions without the O2's. EEC-V no way, as they should be checking for codes... EEC-IV - If the rest of the 'TUNE' is correct, then the car could pass without the O2's. But if anything is slightly out of whack, as it usually will be with evenly a slightly modified Mustang, it is doubtful the car will pass emissions without O2 sensors.

C. Both stats should pass emissions. A 195F stat should make it easier if you are pushing the limit on HC's though.

I'm not trying to be argumentative, or a jerk...
I just wanted to offer my thoughts on the items you brought up.
Which are all good aspect to be thinking about BTW.


jason
 

vristang

15 Year Member
Mar 31, 2005
4,933
101
124
Seattle
Aug 23, 2007
#17
  • Aug 23, 2007
  • #17
I hate double posters!!!

They should be tormented in front of all the other members of the forum.
 

KENS89LX

Member
Mar 12, 2006
302
1
19
Cross lanes Wv
Aug 25, 2007
#18
  • Aug 25, 2007
  • #18
Oh crap! I just installed a 160 in mine....stills rins a little warmer than that.
 
You must log in or register to reply here.

Similar threads

Engine Themostat
  • Mindseye007
  • Jan 30, 2026
  • Fox 5.0 Mustang Tech
  • 2
Replies
21
Views
763
Fox 5.0 Mustang Tech Feb 1, 2026
86HO5.0
8
9
Engine Donor '00 Mountaineer meet '91 Fox
  • 91firecracker
  • May 11, 2026
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
41
Views
927
Fox 5.0 Mustang Tech May 28, 2026
91firecracker
9
Resolved Got Too Hot!!!
  • PonyGTrider
  • Apr 27, 2025
  • Fox 5.0 Mustang Tech
Replies
7
Views
598
Fox 5.0 Mustang Tech May 6, 2025
PonyGTrider
M
Resolved 1988 Foxbody - Overheating Summer
  • MDrisc
  • Oct 26, 2025
  • Fox 5.0 Mustang Tech
Replies
16
Views
703
Fox 5.0 Mustang Tech Jul 17, 2026
fasterthangas
F
Engine Suggestions on an engine rebuild. Stock cam/GT40Ps or aftermarket on both for a fun weekend driver?
  • MadSquirrelTech
  • Apr 28, 2026
  • Fox 5.0 Mustang Tech
  • 2
Replies
23
Views
848
Fox 5.0 Mustang Tech May 7, 2026
MadSquirrelTech
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?