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Discussion Starter #1
I just found out that there is also a 160 degree thermostat, anybody has one?! Any pros? or is it just going to help run your car cooler?
 

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From the Technical Articles:

Change (or remove) the factory thermostat
This is based on the fact that cooler air is denser, so the less you heat the air coming into the engine, the more air/fuel mixture you can pack into each cylinder. An old shade-tree mechanic fix, but it's got several strikes against it. First, you never want to remove the thermostat completely. The cooling system has been designed with the thermostat restriction in mind, and removing it will actually _hurt_ cooling. Second, cylinder wall wear increases as operating temperatures are lowered. The stock Mustang thermostat is set for 196° Fahrenheit. Dropping to 180° will increase wear somewhat, and dropping to 160° or 140° will increase wear dramatically.

On EFI cars, cooler thermostats are rumoured to increase performance because the engine will run richer at temperatures below 180° Fahrenheit. True, the EEC-IV will richen the mixture, but staying in "warm up" mode entails more than just a richer mixture. The EEC-IV will be more conservative with the timing curves, and will never get into "closed loop" operation (where it uses the oxygen sensors to fine-tune the mixture). The result will likely be poorer drivability and decreased performance. Also, catalytic converters can be damaged over time by an engine that's continually running rich.

VERDICT - Don't remove the thermostat entirely, and don't use a thermostat below 180° Fahrenheit on an EFI car.


http://www.tccoa.com/articles/overall/mods.html
 

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Discussion Starter #6
Hhmm.. Should have searched uh?!:confused: Thanks guys!!
 

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" and dropping to 160° or 140° will increase wear dramatically."

my 95 mark 8 got a 160 thermostat at 78,000 miles and still had one in it at 400,000 miles when it was stolen.

I logged ECT and usually while running down the road my coolant was about 10-14 degree's above the thermostat...usually 170-174 range.

just because you put a 160 or 180 thermostat in the car that doesnt mean that's the temperature the car is gonna run at.


IMHO if your oil temp reaches 212 degree's then it's as warm as it needs to be.
at 212 the water boils out of the coolant and at 212 degrees any fuel contamination has long been vaporized.

stant makes a 160 for the 4.6 2v PN# 133396
 

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"On EFI cars, cooler thermostats are rumoured to increase performance because the engine will run richer at temperatures below 180° Fahrenheit. True, the EEC-IV will richen the mixture, but staying in "warm up" mode entails more than just a richer mixture. The EEC-IV will be more conservative with the timing curves, and will never get into "closed loop" operation (where it uses the oxygen sensors to fine-tune the mixture)."

On my EEC IV Mark 8 the temperature to "switch FROM cold table TO base fuel table" is 160 degree's.. since the car ran 10-14 degree's ABOVE 160 at no point or time is the car operating IN the wrong fuel table.

ALSO the coolant temp to "switch back" to cold table is set 10 degree's below the above scalar.. meaning at 160 the car goes to the base fuel table..and the temp has to fall BACK to 150 for the car to go back into the "cold fuel table".

On my OBDII mark 8 the sensors start switching at or about 90 Degrees of ECT, so the car doesnt get stuck in "open loop" either.

BUT.. your PCM setting may differ from what I listed above.. I'm only talking about what I have seen in a first gen 400K mile car and my second gen that I just got about 30K ago.
 

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On my OBDII mark 8 the sensors start switching at or about 90 Degrees of ECT, so the car doesnt get stuck in "open loop" either.
Totally agree I'm tired of hearing that a car will remain in open loop with a 160 T-stat. All it takes is a scanner plugged into your OBDII port to realize cars switch into closed loop at temperature bellow 100 degrees F.

I personally prefer a 180 degree T-stat as I feel it keeps a car plenty cool. Also no matter what T-stat you choose I recommend getting your fans adjusted to jive with it. It doesn’t make sense to have a car that runs at 170 degrees but the cooling fans don’t come on until 220.
 

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Thermal efficiency is a big part of the engines. The cooler you run the engine, the less thermally efficient you are. I have always heard this from many mechanics. You would never even notice a difference. If you wanted to show a difference show some tack slips of stock/180/160 thermostats with whatever EEC updates you wate. Of course these engines are rebuilt every race, but here is what they do at Nascar.

Heat is on
Steve from Redwood City, Calif.: At what temperature do the Nextel Cup teams run their engines? Specifically, what water temperature do they consider "normal" ... 180 degrees, 230 degrees .... ? I'm interested as I've seen debates on whether an engine gets more power when it runs "cool" versus runs "hot."
Tom Jensen: I walked out in the garage here at Phoenix and put your question to Robert "Bootie" Barker, crew chief of Johnny Sauter's No. 70 Chevrolet. He told me that optimal temperatures are 200 degrees for the water and 240 for the oil. In general, he said, teams try to get the oil as hot as they can, without driving the water temperature up too much, adding that when the water gets above 220 degrees, the motor loses power.
 

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Thermal efficiency is a big part of the engines. The cooler you run the engine,
adding that when the water gets above 220 degrees, the motor loses power.
Thermal Efficiency?
That's a neat set of words, but...

The heat in your radiator is the "HEAT" that is left over from the combustion cycle.
It's wasted heat...holding that heat in the radiator only lowers the amount of HP the engine can make by increaseing the AIR INTAKE CHARGE.

Since you quoted Nascar, lets take that a step further or backwards.
Roundy Round racers often run 160 thermostats or NO THERMOSTAT at all, those with no thermostat run a flat washer with a opening in the middle that keeps their car at the temp they "CHOOSE" to run.

There is a formula the roundy rounders have used for many years.
Every 10 degree's you drop the AIR INTAKE CHARGE you net 2% HP.

2% doesnt sound like much until you "do the math".

Take a 300HP engine (such as a 4v DOHC)
2% of 300HP is 6HP

you drop the intake temp from 200 degrees down to 170 (via a 160 thermostat) and you've increased the HP of the engine by 18-20HP.
Far more HP gain that "YOU" got out of butchering that MAF sensor.

If you want to ignore 18HP feel free.

Ever wonder where the HYPERTECH CHIP gets its 20HP...it AINT IN THE CHIP, it's in the THERMOSAT that they tell you to run "WITH" their chip.

Feel free to leave that 18HP on the table.. it matters not to me.
MATH and PHYSICS dont lie.
 

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SInce you asked about "tack times"...

Recently 01-30-09 I went to HRP, ran the car "HOT" off the street with no cool down
ECT was 200 degrees
IAT was 80 degree's
Car ran [email protected] caculated hp onthis run 252.12 HP

Cooled the car down for 1 hour
ETC was 175
IAT was 55
Car went [email protected] caculated hp on this run 265.17 HP

See what 25 degree's of coolant temp and 25 degree's IAT do to ET's.
..there you have it..13 HP

those nascar mechanics would cut off their left testicle for 13 HP more than the rest of the field.
 

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haha I said tack times. And Nascar would cut it off like you said, but they found the optimal temperature to be what I posted.

Well relating to the track times I first ran my Cougar at 15.7. All that was done was an aluminum cold air intake all the way to throttle body, underdrive pulley, and modified the MAF. Now I get 15.3S. According to your calculation what horsepower increase does that make?

Also I'd like to see you start cold first and then hot to see the difference hopefully with less time in between.
 

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Thermal efficiency is a big part of the engines. The cooler you run the engine, the less thermally efficient you are. I have always heard this from many mechanics. You would never even notice a difference. If you wanted to show a difference show some tack slips of stock/180/160 thermostats with whatever EEC updates you wate. Of course these engines are rebuilt every race, but here is what they do at Nascar.

Heat is on
Steve from Redwood City, Calif.: At what temperature do the Nextel Cup teams run their engines? Specifically, what water temperature do they consider "normal" ... 180 degrees, 230 degrees .... ? I'm interested as I've seen debates on whether an engine gets more power when it runs "cool" versus runs "hot."
Tom Jensen: I walked out in the garage here at Phoenix and put your question to Robert "Bootie" Barker, crew chief of Johnny Sauter's No. 70 Chevrolet. He told me that optimal temperatures are 200 degrees for the water and 240 for the oil. In general, he said, teams try to get the oil as hot as they can, without driving the water temperature up too much, adding that when the water gets above 220 degrees, the motor loses power.
Funny you mention Nascar.... I can tell you there is on major difference between a Nascar engine and a fuel injected mod motor... I already gave you hint ;)
 

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And what's that have to do with the explanation of why a lower water temperature is better and why the optimal temperature is different for a carburetor?
 

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And what's that have to do with the explanation of why a lower water temperature is better and why the optimal temperature is different for a carburetor?
Optimum manifold temps are vastly different for "carbed cars" vs "EFI cars".

Carbs require heat in the manifold to keep the atomized fuel in "suspension".. whereas an EFI car is directly injecting the fuel into the cylinder AT the port and doesnt suffer from "puddling in the manifold" like carb cars do.

This is why 190-210 Thermostats were put into cars, for fuel economy reasons in a car with a CARB.

it's old school enginnering being uselessly carried over into the EFI world.
 

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haha I said tack times. And Nascar would cut it off like you said, but they found the optimal temperature to be what I posted.

Well relating to the track times I first ran my Cougar at 15.7. All that was done was an aluminum cold air intake all the way to throttle body, underdrive pulley, and modified the MAF. Now I get 15.3S. According to your calculation what horsepower increase does that make?

Also I'd like to see you start cold first and then hot to see the difference hopefully with less time in between.
not enough real "DATA" to give a horsepower estimate.

If you didn't make the runs on the same day, they are not valid.

here in houston there is a .5 {half a second) swing from summer to winter ET's.

SO.. if you ran your 15.7 in the summer or spring and the 15.3 in the colder months THAT could easily produce the .4 ET swing you have "credited" to your mods.

I made my passes in the manner that gives the best data.
I made my "hot pass" right off the street.. to get my "slow time".
It take more than 3 hours to completely get a 4.6 dohc completely "cooled down".

so I made my hot pass first, then cooled the car down for an hour until the coolant temp was at the temp I wanted to run the second pass at.

and.. my passes were on the same day, same car, same driver.
if your test passes were NOT on the same day, that is pretty much useless data.

BUT if you post the complete timeslips including the 60 foot times, 1/4 mile ET and MPH AND the cars "actual weight".. I can guestimate what the HP increase was... but again, if they were run under different conditions, this isn't "solid data".
 

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damn now i am confused again. I am doing a PI head swap on a 97 GT and was a little worried about more detonation per the added compression so I got plugs (motorcraft agsf22fm) one range cooler and a stant 170 degree thermostat. Doesn't heat help detonation to happen? Should I stay with the stock? What degree is it? 190?
 

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The cooler thermostat and colder plugs should help curb detonation
 
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