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How the Dodge Demon Uses Air Conditioning For More Horsepower

Date: 09/04/2017

Performance cars don’t like air conditioners. Racing cars instead, have little bottles of water with tubes to keep the driver from dehydrating. This is because ACs add weight and sap power- about 5-12 HP. For smaller engines, they sap so much power that turning the AC off, acts almost like a boost button. But what if you could use the AC to get more power instead?

Sounds implausible or even downright idiotic. The Dodge Demon achieves just that. It sounds implausible, because it means creating more engine power by using engine power but Dodge engineers have figured it out.

The system is extremely complex. First we look at the basic setup of the Dodge Demon, without the AC wizardry. The engine gets air from the outside through the air filter, like any normal engine. This then goes through the supercharger – a 2.7 liter supercharger - which compresses the air like any supercharger, allowing more air for combustion. This causes the air to heat up. This is not welcome as hotter air is less dense and is more likely to create knock. The supercharger also draws power from the engine, but we’ll get to that later. The hotter air from the supercharger, is then sent into an intercooler that cools this air which then sends it into the engine. And then the all familiar internal combustion takes over.
The engine needs cooling of its own. This happens through a radiator and an engine cooling fan, like any other internal combustion engine. A water pump, that draws power from the engine itself, pumps cooled water from the radiator into the engine cooling circuit. This hot water is then pumped into the radiator, where it is cooled by the ambient air.

The intercooler needs cooling too. It has its own cooling circuit that has its own pump. This pump however, is driven by electricity from the battery. Coolant from the intercooler goes through a heat exchanger at the front of the car. Here, it is cooled by the ambient air but is then cooled further by a power chiller before being sent back into the intercooler. We’ll get to the power chiller in a bit.

The air conditioner, roughly, works with the help of a compressor that is driven by the engine power. This compresses the hot refrigerant (in gaseous form) and sends it to the condenser at the front of the car. Here, some of the heat is removed from the refrigerant, but more importantly it is no longer in gas but liquid form. It is then sent into an expansion valve, where it expands and cools further. It is then sent into a cabin evaporator, from where it can finally be sent into the cabin, through the AC vents.

Here’s where it gets different. This chilled air in the intercooler, can also be sent through a power chiller instead. The power chiller is used to make the air travelling into the intercooler even colder. By a whole 10 degrees. This is in addition to the 45 degrees Fahrenheit temperature drop, achieved by the heat exchanger. This leads to an increase in power output of nearly 5.5%, according to Dodge literature. Unfortunately there is a choice. You can either run the power chiller or the AC. Not both together.

This means that contrary to normal cars, when the Demon is on the drag strip - its natural habitat- the AC needs to be on. The AC compressor is in fact, connected to the engine with a clutch. This clutch keeps the power chiller – coolant circuit running the whole time the engine is under 4500 rpm.

If any of this made sense, then the obvious question would be why. Why would you use engine power to create engine power? Frankly this is nothing new. Not even in the car itself. Because the car uses a supercharger. The supercharger uses about 90 HP to run. But for that, you get a whole extra bar of pressure, which means more air goes into the engine. This gives it all the power that the Dodge is known for. More power than it takes to run the supercharger.

The fact is, that the quest for power knows no bounds. Efficiency and comfort be damned. And this car is all about power. It has a 6.2 liter V8 and running it on High Octane gives 32 extra horsepower. It goes from 0 to 60 mph in an eye watering 2.3 seconds. This is the car with the largest functional hood scoop, ever fitted to a production car. It even has another intake that replaces a headlamp. This means that at peak power, 1150 cubic feet of air is going through all the intakes, every minute. This is more than the Hellcat V8 before it. It is in fact, the largest induction volume of any production car. The car even has an After Run chiller that ensures that the car is on its proverbial toes, even after recently completing a run. This system keeps the engine cooling fan and the cooling circuit running, even when it is not required - even when the car is turned off - so that the car’s intake temperature is kept low.

All of this is made possible by the mad engineers at Dodge’s SRT division, so that customers can actually enjoy the 840 bhp of power and 770 lb-ft of torque that car comes advertised with. This machine is truly a collection of demented numbers, kept running through mechanical wizardry of some very talented engineers. Dodge has always been an eccentric when it comes to their SRT division, whether it be the Viper,the Challenger, the Hellcat or the Demon. The amount of power they put in a road going everyday car, is rarely seen even in supercars. And then, they sell it for as low as 85 thousand dollars.

But the true miracle here is the internal combustion engine. In a time when the threat of the electric car is larger than ever, this car and its engine can be seen as a swan song, to the marvel of mechanical engineering that is the internal combustion.

If you have a nice sports car or any vehicle that matter and it needs a little TLC bring it in to our new Mesa Az location today. We fill all makes a models.