I am just wondering if this is too hot for my car. I heard that the best thermostat is 160 degrees. But I also heard that 220 is the best to have your engine running at.


Will a 195 degree thermostat work or not?


I live in AZ so that might make a difference in what thermostat i get too.
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85 Trans AM
305 5sp
180,000 miles
KYB struts front shocks rear
polyurathane bushings
solid panhard bar
new world class t-5
new clutch

[This message has been edited by 85TA-AZ (edited March 04, 2001).]

 

The 195 will work fine. The fan doesn't turn on until 225, so a cooloer thermostat will do you almost no good unless you change the fan switch. Hypertech makes one that comes on at 200 and off at 185. I use that in conjunction with a 180 degree thermostat. I think a 160 is too cold for normal use unless you are racing in a very hot climate. Also, i fyou plan to use the car in the winter, a 180 is about the lowest you should go.

 

TA,

195°F is the rating of the original factory installed thermostat, so I think anyone would have trouble justifying the argument that it is too hot. Your car should operate just as it always has, and if that's good enough for you, then you should be happy.

On the other side of the coin, if you want your engine to perform a little better, and last a little longer, you can install a 'stat rated at a lower temperature. Lowering the coolant temperature allows more spark advance, better fuel enrichment for acceleration, and helps prevent the oil from reaching a critical breakdown temperature, keeping you engine newer, longer. But you can't overdo it, either.

Presuming your TA is a TPI, if you delve into the ECM programming for your engine, you'll discover that there are several coolant temperature dependent functions that should help you decide what is too cold. If you are using an aftermarket or custom PROM for the ECM, your scales may vary, but with an O.E.M. PROM there are several important functions that don't get enabled until the coolant reaches 176°F (80°C). These include Acceleration enrichment multiplier factor, Acceleration enrichment decay factor, Target IAC idle RPM, Fuel limiting factor timer counts, Cooling fan duty cycle for AC, and EGR Duty-cycle at MAX percentage. If your car must pass an emissions inspection, you need to reach that operating temperature. A 170°F thermostat begins to open at 170°F, and is fully open at about 182°F. If your coolant temperature sensor is in perfect operating condition (i.e., no variation from factory standard) and the replacement thermostat is perfectly set to 170°, you might just be able to reach the necessary temperature of 176°F. It should definitely be safe to use a 180°F thermostat, and I've had one installed in my '86 TPI for several seasons with no problems (and no overheating, either). A 170°F thermostat is more difficult to find, and might be on the borderline. A 160°F thermostat is almost definitely too cold for a TBI or TPI engine with stock PROM. If you have an E4ME carburetor, you might be able to use it with few problems, but not likely with an injection system.

Another thing to consider is that the ECM still controls the fan operation on your TPI. In order to take full advantage of the extra cooling, you'll need to install an auxilliary fan switch or fan control. This is relatively easy and inexpensive, but should be planned when you do the thermostat swap/cooling system flush (you WERE planning to flush the system when you changed the 'stat, weren't you?)

MikeInAZ has an article about this on his site, The 3rd°, and Mike used a DeRale fan control for his, about $40.00.

I used a direct sensing element on mine, and I have an article at this link: Cooling.pdf. That file requires Adobe Acrobat Reader to view/print it.

My installation is more like this:


I'm glad you're planning ahead. Living in AZ probably requires all the cooling you can get.


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Later,
Vader
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"I'm'a do Things My Way - It's My way or the Highway."

[This message has been edited by Vader (edited March 04, 2001).]

 

I live in southern IL and it gets to the 90's in the summer (probably nothing compared to AZ), the 180 has always been fine for me, never overheat's nor is it too cold for those -5* winter's that we sometimes have.

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89 IROC-Z 350 TPI

-Flowmaster Catback
-Performance Resource Chip
-700R4 (Rebuilt) Too much done to actually list
-K&N Airfilters
-Ported Plenum
-2.77 Gears (not much to brag about but eh, its there)
-MSD 8.5 mm plug wires
-Problems every other day with the car (probably not a mod, but to me it sure makes a difference)

 

I was running a 160* in my car with the Performance Resource chip and it was working pretty good. Then I read that you should use a 180* stat with that PR chip, so I got a 180* and I haven't had a chance to see how it works as my car has been disabled now for about 6 weeks. But I'll let you know how I like the 180* compared to the 160* in a week or so.

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1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!

 

I agree with Jeff (Vader); the T-stat has a LOT of parameters that are inside the eprom that needs to be changed in order to get the full benefit. A 160* T-stat is too hard to control. The engine thinks it is in "cold start" and causes a lot of problems. Too hard to control properly.

I personally believe (now...my opinion has changed over time with all this testing of the eprom) that the BEST combo is a HOT engine with COOL oil. So a hot T-stat with an external oil cooler is the best setup IMO.

But if you don't have an external oil cooler, a 180* T-stat works quite well and doesn't require too much "fiddle farting" in the eprom. Even something as the IAC "learn mode" is affected by the temperature. There is a LOT more affected than most people think inside the eprom and I am finding new stuff everyday.