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160 Thermostat


Sep 14, 2001
Chicago Ridge, IL, USA
'04 Z-WOW-6
I have my '93 LT1 up on blocks replacing shocks and the optispark. As long as the H2O pump is off I thought of swapping out the original thermostat with a 160 degree. Can I just do it or will I have to also change or reprogram the chip? Any real life experience would be appreciated.

Ken Linderborg
i put a 160* thermostat in my 96 camaro without changing the chip and i never had problems. i noticed the car stayed cooler for a bit longer but was back to running at the normal operating temperatures within 30 minutes.
i think if u change the chip all it does is turn on your fans at a lower than factory setting, there by insuring your car doesnt go over a certain temp.
88canadian vette's info is interesting in that the 160" thermostat didnot ultimately effect the final temp reading. This would lead you to believe that the only necessary change would be to reprogram the fan(s)
& forget about the thermo?

I would try it without the thermo
& see what results you get.
You really should do both at the same time to get the benifits of a cooler running car.
If you do just the thermostat, it will not cause any problems, will cool the car a little lower when driving on the highway, but not when ideling in traffic. If the fans come on below 190deg stock thermostat, it will do no good because the water would not be circulating thru the cooling system (and motor)

Ken, the easiest time to change the thermostat is now, while you have the cooling system openned up. I would change it out now!

I cannot give specific's on a 1993, but I'll bet you could install an inline manual switch to turn the fan / or fans on at the flip of a switch under the dash when in traffic or hot conditions. Or just bite the bullet and install a new re-programmed chip!

Best of Luck,
Prom chips

Ken, if you go with a custom prom you can tell your chip burner what temperature to program in for your fan engagement. The other advantage of a custom prom is it can be programed to take advantage of your other mods i.e. headers, catback exhaust, the altitude you run at etc. etc. etc. Good luck 91 ZR1 Red/Saddle #2039
Ken, I just installed a lower temp fan switch. It turns on at 207 degrees and off at 86 degrees. I left the stock stat in because the bolt that goes into the water jacket was frozen and I did not want to twist off that bolt unprepared.
It appears to work just fine the way it is. This morning going to work the fans never came on. Since it turns on at 207 the temp never got to that. Because the traffic was light. Going home tonight will probably be another story. I expect it to come on. But the purpose in this endevour was to keep the engine from getting into the 220's like it has been doing. It appears to be doing that quite well without lowering the temperature of the thermostat.
Also there are two fans on my '85, one is turned on by the fan switch in the block, the other is turned on by the ECM. Now they are both turned on by the switch so the temp goes down dramatically then the fans shut off. Works pretty good so far.

I cannot give specific's on a 1993, but I'll bet you could install an inline manual switch to turn the fan / or fans on at the flip of a switch under the dash when in traffic or hot conditions.

I can say that this worked wonderfully well on my '89, and has the added benefit of improved A/C performance with both fans on. I did it with a toggle switch under the dash wired to the fan relays, so the switch wasn't carrying full fan current. (The a/c works better when there's better heat transfer at the condenser, plus you get lower head pressures, so you won't have the compressor clutch burn out, as is all-too-common here in North Texas)

BTW, I did the 160 'stat several years ago, with no ill effects even though the aftermarket chip makers would have you believe that a re-calibrated chip is essential to make this work.
One of the things you get from cooler running is reduced tendency to spark knock, meaning that the knock sensor does not have to dial the spark back as much, meaning more horsepower without running octane booster or race gas.
In fact, my car runs fine on regular. I just use premium when I anticipate wanting to run fast.

I would go with the lower temp fan swich if your not getting a chip. If you go with the 160 stat get the chip, it works better that way.

Remember, we live near Chicago and it gets pretty cold sometimes in the fall. The car will get down right *****y on a 40 degree day. I opted not to go with the 160 stat because of this as I drive the car whenever the roads are clear of salt.

Thanks for all the suggestions. I investigated Ecklers and Mid America for the parts that might be available. I decided to keep the 180 stat and just install a manual switch for control of the fans. My main reason for looking into the subject was that when I autocross ( every chance I get ) , the car really heats up. I really can't change the chip and still stay in the street class, so changing the stat seemed a waste of time,energy and $. Again thanks for your interest.

There is probably good reason for them not letting you run that chip in "street" class Ken. It increases the spark at WOT and I think it also removed (or increases) the rev limiter. I am guessing that is all it does. I have ordered an EPROM programmer so before long I will know for sure what it does but I am pretty sure of those two variables.
In crashing around those thirdgen links I noticed that the '85 Fiero and the '85 Corvette both take the same chip. I did not carry it out for enough to see if they are both programmed the same but I bet they are. (The Hypertech chip)
A few years ago when I was in the Fiero community (before I got waxed by a Corvette! :)) we compared that Hypertech chip to a stock chip and those were the only differences. I would almost bet the farm that the Corvette is the same. But I will know for sure when my programmer arrives.

Good luck with it Ken, it sure work well that way........
Change to the 160 therm and make your own switch to jump both relays, you will have to watch the temp to turn on the fans yourself, but its way cheaper and lower temp therm allowys the fans to ultimately bring the coolent temp down to near the therm rating. Total investment is 30 bucks. Leaving the line at 170 is great and if you have to wait in the staging lanes and dont want ot keep starting and stoping the motor, its the way to go. Dont forget to bypass the coolent line on the TB.
That's a good idea Warren. I did something similar, I bought a 160 degree thermostat and a 200 degree fan switch. Since the bolt was frozen on the thermostat housing I wound up just putting in the fan switch. It works pretty well so far. I suspect when summer really hits though the fan will stay on a good bit of the time. Well, they did before anyway. But right now the temp stays at about 197 to 200. Once in awhile (in traffic, etc) it goes up as high as 207 but then it quickly (because of the fans) drops to about 190 again. It has excursions to 187 but it hovers around 197 or so except on the highway where it runs about 186. I will have to remove the intake manifold to change the stat so I think I will try it this way awhile.
The good news is I am no longer boiling away the anti-freeze (or water) because it had a loose bolt on the stat housing. (not the one that was frozen! :)) It was causing the system not to pressurize.
That sucks about the frozen bolt, I never feel good about forcing aluminuim so would not want to break it.

On my 95, the temp would go right up to 220 or higher and than the fan would kick on. Though the car had 13000 miles on it when I bought it in January, all of the hoses were dried out and brittle and some of the wiring harness was also cracking. No doubt caused by the heat cycling. If the water was getting hot I bet the tranny fluid was cooking good to. So now I let it go to 180 before I throw on the fans.
I also have found my bolts on the thermostat housing stuck. I was gonna swap a 180 thermo in for my 195 one. I didn't see the need for a 160, since my coolant temp is never below 180 after warm-up anyway.

Any ideas on getting these bolts unstuck? Does it work better in the morning when its cold? Does WD40 help?
It seems that these cars sure do run very warm from the factory. I recall reading in several places that the factory setting for the fans was actually 228.

I know alot of people just don't feel comfortable with that high of a temp. I have yet to do anything with my car in this regard, but toy with the idea from time to time.
I reprogrammed my fans to come on a 193.....they stay on most of the time, but they keep the temp below 205 at ALL times. Without the fans this low, my car sits around 215.
My fan kicked on at 228 when controlled by the 'puter. It would hit 230 before it would start to cool. Now I knew come late July and August in Vegas I was gonna be in trouble. I put in a manual toggle switch today to a ground and the green/white wire coming out of the fan relay. Headed for the stop and go action on the strip and hit the fan at 180 and never broke 190. I put the toggle in the center console so I can reach it with my finger when in first or third gear. Makes it hard to forget when you can see and touch it. My fiance was being a smart a** and asked if it was my 'nitrous' switch.....little does she know. :J
warren -

The Build Sheet is essentially the "recipe" for a car that is being produced. A Build Sheet contains the following information: VIN number/sequence number, all factory installed/original options, paint color/code, leather color/code, engine that was installed, tranny that was installed, rear gear ratio, date and time of completion of the vehicle, rim size(s), tire size(s), Dealership to which originally delivered, original order number, etc......

It's just a nice piece of paperwork to have with the car. :)

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