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Sanity check regarding thermostats and cooling

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
I installed a scirocco radiator and two big fans over the summer. I also installed a 180* t-stat and played with my coolant offset a bit to get my OL thresholds inline. This all worked fine and dandy. Now it's winter and I'm rarely seeing my car go over 180*. No big surprise there given the t-stat I have. it drives well enough with the coolant offset telling the car it's 10* warmer than it actually is, but I'm getting a bit concerned that driving around at 174* (normal cruise. it gets up to 186* when I drive with a bit more spirit or up a long hill) might not be the best thing for the motor, either. I mean it's not the end of the world, but it's not where (I think) the car wants to be.

There's a 190* t-stat sitting in the passenger seat of my car right now. I plan on putting it in after lunch today, but I wanted to make sure I'm not crazy. I've searched the forum and there's a number of discussions regarding problems people have running much colder than me or much warmer than me. So, where does the car like to be when running? Stock temp ranges (190-206) or 2g ranges (180-196)?

What I really wish is that someone made a 185* t-stat for our car. seems like I'd get the best of both worlds. Without it, I suspect this summer I'll either be replacing the fans I got at Autozone with high-flow/high-performance fans, or swapping the 180* t-stat back in.

Well that, or putting in a bigger radiator, but f*** if I want to do that again.
 
Last edited:

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
Done and done. Temps now settle around 190 (as you might expect), and run between 190-196 under normal driving. Pretty much exactly what I was hoping for. Now when the weather warms up, we'll have to see how things behave...
 

diambo4life

Well-known member
Joined
Jul 7, 2013
Messages
315
Location
Edmond, Oklahoma
I would be shocked if you didn't overheat in the summer with those AZ fans. They are rather worthless. I worked there and have run them. You may need to get a nice high output fan. The difference in the amount of air they move is staggering. I suppose you could just wait and re-evaluate summertime.... /ubbthreads/images/graemlins/dunno.gif
 

thomcasey

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Joined
Sep 24, 2014
Messages
907
Location
Indianapolis, IN
I ran 1 @ 10" FAL fan on a single core Scirocco radiator in my swapped Colt. I could never get that thing to overheat, even in 95°, high humidity heat sitting in line @ the shootout. For Oregon, he could be good considering he has two. The Scirocco radiators are amazing at cooling. Considering they are designed to cool at constant high RPM since VW's are geared high like DSM's
 

Tisquantum

Active member
Joined
Sep 20, 2015
Messages
25
Location
Northern Willamette Valley, OR
I as wondering about all this myself as the car has about 10 miles on it with the Scirocco rad in it and reliability is my top priority. I've commuted high strung, finicky 4G63s before and thermal issues are the LAST thing I want to deal with.

Engine compartments with out any provision for air to leave over the cowl are bad in many, many ways to persons with performance in mind. We all know that thermal exchange is a function of surface area and flow. Even a mod as simple as propping the rear of your hood 1/4" to 1/2" with washers and longer bolts will reduce drag and lift, increase front grip at speed and provide more efficient cooling both at speed and in traffic.

Venting the rear of the hood is obviously much easier, less permanent and most important of all less conspicuous than gnarly hood vents.
 

thomcasey

Well-known member
Joined
Sep 24, 2014
Messages
907
Location
Indianapolis, IN
You have other issues if you need to vent the hood. I have never had under-hood temp issues unless the fan stopped working in traffic. Proper coolant mix, a good radiator and a quality fan for under 30mph traffic and you should be good. Now, if there is a big 'ol FMIC blocking flow to the radiator you then might want to be sure the airflow ducting is in place and maybe alter it to fit with the FMIC and such. This will help the cruise airflow and can help the fans pull fresh air during low speed/traffic (Here is where the quality fan and proper coolant mix comes in as over 30MPH, you get more airflow than with a fan). You can also consider some coolant additives such as Water Wetter and ensuring all heat deflectors are in place or use heat tape on exhaust components to help keep the temps down.
 

prove_it

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Joined
Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
/ubbthreads/images/graemlins/rofl.gif Venting the rear of the hood.
 

iceman69510

Turn Right Racing
Staff member
Joined
Mar 5, 2001
Messages
10,964
Location
Michigan
Cowl induction, baby!
 

prove_it

Well-known member
Joined
Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
It still amazes me that people think that it vents air. For 50yrs muscle cars do it to for more air intake, yet people still think it lets air out. /ubbthreads/images/graemlins/rofl.gif
 

gvr4ever

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Joined
Aug 6, 2002
Messages
6,190
Location
central Indiana
I thought the vents in the EVO/GVR4 was to let heat escape. Some cars got functional ram air, others have functional vents for a top mount IC. Can't bunch all hoods together.
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
I figure come summer, I'll be putting in better fans. At the time, I was just working with what i had on the timeline I had. I'm not excited about the idea of having to swap thermostats twice a year. Not a solution.
 

thomcasey

Well-known member
Joined
Sep 24, 2014
Messages
907
Location
Indianapolis, IN
This summer, running a stock Galant single core radiator, stock fan, stock 195° thermostat driving the galant to the shootout I averaged 170°-180° temps before the thermostat at speed (over 40) in the Ohio heat/humidity. Fans kicked on a couple times while waiting to enter the race park. Having a VR4 or Colt for that matter, you have better airflow through the radiator even with a big FMIC due to having an actual grill to take air in.

I can see running a 180° thermostat in Arizona/Nevada/New Mexico/Texas where temps tend to soar, but in the PNW, you should not have issues unless your cooling system isn't in good shape.
 

prove_it

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Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
Quoting gvr4ever:
I thought the vents in the EVO/GVR4 was to let heat escape. Some cars got functional ram air, others have functional vents for a top mount IC. Can't bunch all hoods together.




Yea the hood vents over the engine will, due to the louvered design creating negative pressure trough the holes. He mentioned lifting the rear of the hood. This lets air IN due to the high pressure area generated at the base of the windshield.
 

89Patches

Well-known member
Joined
Jan 30, 2013
Messages
723
Location
Ontario Canada
Quoting Tisquantum:
Even a mod as simple as propping the rear of your hood 1/4" to 1/2" with washers and longer bolts will reduce drag and lift, increase front grip at speed and provide more efficient cooling both at speed and in traffic.



This is by far the dumbest thing I have ever read while being a member here. /ubbthreads/images/graemlins/uhh.gif
 

prove_it

Well-known member
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Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
I missed the front grip part. OMG too funny.
 

prove_it

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Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
Your the one who posted a long technical sounding post with no knowledge of what your talking about.
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
Quoting prove_it:
Yea the hood vents over the engine will, due to the louvered design creating negative pressure trough the holes. He mentioned lifting the rear of the hood. This lets air IN due to the high pressure area generated at the base of the windshield.



Well sure, but aren't they meant more for a car that's at rest and not in motion? If your car is overheating at-speed, you've got larger problems since at that point, the fans become irrelevant as well. At that point, it's all about the efficiency of your radiator, coolant mixture, and AFR's (since lean=hotter EGT's), right?

The only issue that I need to solve for in summer is my resting temps. The car likes to get a bit hot in stop-and-go traffic in the warmer weather. I figure new (READ:real) fans will help and hood vents won't hurt.
 

prove_it

Well-known member
Joined
Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
Quoting Fish:
Don't the Honda guys stack washers under their hoods for some reason?



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