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I saw that a lot of people have a 180 degree thermostat upgrade. What kind of performance advantages does this have? Also any recommended companies? Thanks in advance.
 

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It's lowers the engines temperature to prevent heat soak. When temps are higher, the computer pulls timing to prevent detonation. Jet makes a great t-stat that can be purchased from one of our vendors.
 

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Discussion Starter · #3 · (Edited)
Thanks for the quick reply. Modifying N/A V8 is a whole new thing for me. The last vehicle I had worth modifying was an Audi TT 225. It was a 4 cyl. turbo charged coupe. But pulled the triggered and just ordered the Jet T-stat from BMC.
 

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I saw that a lot of people have a 180 degree thermostat upgrade. What kind of performance advantages does this have? Also any recommended companies? Thanks in advance.
I personally don't find it an upgrade at all, but a downgrade. Reducing cooling system temperatures has a lot of drawbacks with a street driven car. A race car is a whole different story. Reducing cooling system temperatures will increase engine warm up times, resulting in greater fuel dilution of the oil, which reduces both oil and engine longevity. This will also cause a decrease in fuel economy and an increase in emissions as well. I think a far more effective method of reducing engine operating temperatures is by using a good synthetic oil, which can reduce engine operating temperatures up to 50 deg. F., without affecting cooling system temperatures.

When modifying a car I think it might be best to compliment what a well trained group of engineers already came up with, (the stock design), not totally toss it out. The engineers who designed your Challenger probably aren't stupid. :bigthumb::woot:
 
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No...but they were probably not trying to get the best performance in a warm climate but the best emissions overall.
 

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No...but they were probably not trying to get the best performance in a warm climate but the best emissions overall.
Exactly. They have such strict laws now wit emissions and the cars have to to be able to run in all climates not just Hot places. Same reasons they use their filter and not CAI from factory and alot of other little things.
 

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the dyno has shown 7hp to 10hp gains on the 5.7 hemi. this is the best bang for the buck. 10hp for $4. nothing compares.
 

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I read an an article in Mopar Action magazine where they showed the 6.1 running stronger as it got warmer. I agree with most here that it is a downgrade. Warm engine, cool intake is the key to performance. I bought one and it is in the package, probably for good.

the dyno has shown 7hp to 10hp gains on the 5.7 hemi. this is the best bang for the buck. 10hp for $4. nothing compares.
 

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ask those with the fastest hemis as see what they say. when the engine temps go over 190*, performance falls off.
 

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ask those with the fastest hemis as see what they say. when the engine temps go over 190*, performance falls off.
Shhhh.. Don't give out all of the secrets. Otherwise all of our cars will run the same. :rofl:
 

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I have never seen synthetic oil lower temps in any engine i have used it in. I still use it in everything I own because I think it is a superior product, but it doesn't run any cooler, not even in my air cooled Harley. What it does do is stand up better at high temps. Its been proven in many tests that syn oil breaks down at a much slower rate at temps over 200 degrees.

Oh, and about the stat, been using that trick for years in 5.0 Mustangs. I'm a believer!
 

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BS, that only may apply when in the balda$$ desert. I am an engineer, licensed mechanic and raced since 1978. I would get into the dynamics of disapation but would probably be wasting my time.

ask those with the fastest hemis as see what they say. when the engine temps go over 190*, performance falls off.
 

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if u know what you are talking about let us know i for one would like to know.
 

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highberg, I don't think he is saying that the temperature itself is killing the performance, but the computer is pulling timing out of the motor at these temps. I don't know this to be true but the theory seems sound.
 

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No question, there are numerous design issues with the current hemi. First, it isn't a true hemispherical combustion chamber as anything with 2 spark plugs can't be. Further, the oil consumption, so called heat soak, etc. are also make this engine less than the original hemi designs.

So, two things to explore;

First, engine heat. Friction coefficient is in play for the mating of parts moving against each other as the engine runs. Friction is reduced in these moving parts as the temperature is raised, in fact cylinder wear is increased when the engine is cooler. This is true until there is too much heat and the factor starts to work backwards. If engine oil is not breaking down and lubrication remains solid, this maxes out around 230F before the curve drops. Also, with higher temps, the burn is more complete therefore producing more energy from the same event. Now, the possibility for preignition can occur from two situations, hot spots created in the cylinders or on the valves. If combustion isn't as complete as in lower temperatures, carbon will form and leave hot spots causing this condition. If the valves are doing this (outside of the combustion chamber), then it is likely a design flaw as the cooling jackets must be insufficient to keep the valves at a proper temperature. People attribute higher engine temperatures to emission control but it was the introduction of closed cooling systems that allowed manufacturers to raise the temperature to where they wanted it. The old rads had no overflow so as they heated, the expansion pushed the coolant out. When it cooled, it refilled with air. Overflows allowed it expand and contract without losing the coolant.

Second, is the fuel charge temperature. Here, the cooler the better. This is the disapation I mentioned earlier. You want to get the fuel very cool as it will cause the air fuel charge to mist, causing droplets. You lose when the air fuel is gaseous. The reason for this is the basis for getting engine power. Volumetric efficiency is what you are after. Fill the cylinder as complete as possible, compress it as tight as possible to receive the highest energy. This is the concept of just about every performance mod out there. Push or allow the engine to breath in an air fuel charge to increase volumetric efficiency. Superchargers and Turbos do this very well as they push into the cylinder and increase volumetric efficiency to above 80% which is not available in normal aspiration. Cams, heads, intakes, bigger valves, etc. are just trying to the get this efficiency as high as possible. So, when the fuel is in liquid droplets, it will expand as it turns to gas and get a higher efficiency. Also why engines perform better at lower altitudes as the pressure helps fill the cylinder. You have about 14lbs at sea level to help fill that cylinder.

Hope some of this made sense. In theory, reducing engine temperatures should not be improving performance. In practice, you should not get reduction unless you are getting above that 230F mark. I agree that car companies are messing with the computers to protect themselves by retarding the spark.

Scan from the magazine I mentioned attached
 

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I 100% agree with everything you just said. I too have some engineering background and have been racing since the 80's. One thing I can't do though is reprogram a computer, so if I can run the engine a little cooler to keep the computer from killing horsepower, seems like an easy fix. I don't think we are running them cold enough to hurt combustion efficiency much if at all. If we were running 160 degree stats in these things I would be worried.

I hope you are not taking my posts as butting heads, I really like technical discussions. This is how we all learn something new. And believe me I am still learning. I do not bring up my engineering background to impress anyone. I mearly bring it up to let you know that I understand the points you are making so that we can continue our discussion. And I certainly am not single minded enough to think that my theory is bulletproof. I welcome anyone to blow holes in it so that we all can learn. I have an itch for anything automotive technical related that I can't seem to scratch.
 

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No offense taken. I got caught up in the 180 thermostat event as so many were making points to support it. I bought one going against my internal judgment just to find this article that negated everything. I live in a reasonable temperature climate at high altitude so I won't put it in. If it helps those at high temp climates to run better, go for it.

A lot of people putting them in have also noticed mpg decreases.

I 100% agree with everything you just said. I too have some engineering background and have been racing since the 80's. One thing I can't do though is reprogram a computer, so if I can run the engine a little cooler to keep the computer from killing horsepower, seems like an easy fix. I don't think we are running them cold enough to hurt combustion efficiency much if at all. If we were running 160 degree stats in these things I would be worried.

I hope you are not taking my posts as butting heads, I really like technical discussions. This is how we all learn something new. And believe me I am still learning. I do not bring up my engineering background to impress anyone. I mearly bring it up to let you know that I understand the points you are making so that we can continue our discussion. And I certainly am not single minded enough to think that my theory is bulletproof. I welcome anyone to blow holes in it so that we all can learn. I have an itch for anything automotive technical related that I can't seem to scratch.
 

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It's lowers the engines temperature to prevent heat soak. When temps are higher, the computer pulls timing to prevent detonation. Jet makes a great t-stat that can be purchased from one of our vendors.

What do you mean by heat soak? Do you mean gas vapor lock? Where I live its usually always around 100 degrees or high 90's so I was also thinking off adding a cooler t-stat but not sure. I heard someone say that when they added the predator he added a 180 t-stat aswell.
 
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