How the Demon 170 Hemi Differs from the Redeye Hemi: Deep Dive

When the embargo lifted on the 2023 Dodge Challenger SRT Demon 170 on Monday, we focused on key parts of the new package, including power, performance, and production numbers, but we didn’t get into how this package makes so much more power than the closely-related Redeye. Today, we dive into what makes the Demon 170’s supercharged Hemi so much more powerful—reaching 1,075 horsepower. (See our initial piece about the 1,025-horsepower, 8-second Demon 170).

Dodge Challenger SRT Demon 170

When Tim Kuniskis introduced the 2023 Dodge Challenger SRT Demon 170 to a small group of media in early March, he held up a camshaft and said that it was the only component that was directly shared between the 6.2-liter Hemi in the Demon 170 and the 6.2-liter Hemi in the Redeye. Everything else was revised, if not replaced altogether.

The Blower

Starting at the top, the Demon 170 Hemi is topped by a 3.0-liter IHI supercharger similar to the one used on the Hellephant crate engine series, and fitted with a 3.02-inch pulley. This blower setup provides 40% more boot pressure and 30% better flow than the Redeye, with peak power at 21.3 pounds of boost. Air is introduced via a 105mm throttle body; fuel is provided by a set of injectors that flow up to 164 gallons per hour. That huge fuel flow is needed for E85, as the engine uses roughly twice as much fuel than gasoline to achieve the ideal air-to-fuel ratio.

Dodge Challenger SRT Demon 170

The Redeye Hemi, by comparison, has a 2.7-liter supercharger with a 3.35-inch pulley, a 92mm throttle body and 700cc fuel injectors, making peak power at 15.3 pounds of boost pressure with roughly half the fuel flow.

A fast-response ethanol sensor, integrated into the fuel rail, constantly monitors the level of ethanol in the fuel system, unlocking peak power when it sees more than 65% ethanol; under that level, the engine stays on the pump gas tune, which delivers 900 horsepower and 810 lb-ft of torque.

Dodge Challenger SRT Demon 170

Demon 170 Cylinder Heads

The Demon 170 cylinder heads are similar to those of the Redeye engine, but due to the incredible cylinder pressure levels under peak boost, the fasteners had to be upgraded. The Demon 170 heads are held to the engine block with aerospace-grade high strength steel studs, but the team was concerned about the strain on the head where the studs made contact. To protect the aluminum, the heads have unique steel inserts where the studs pass through. The steel inserts to take the load of the stud, rather than the aluminum head material, leading to 38% more load clamping power.

Dodge Challenger SRT Demon 170

The other key change to the heads of the Demon 170 Hemi are nitride-coated intake valves and upgraded valve guide/seat material. Ethanol has a slightly corrosive nature and can cause accelerated wear to certain components, and these unique materials in the cylinder heads help to prevent any of that. Of course, the Demon 170 also has unique spark plugs for the ethanol application.

Dodge Challenger SRT Demon 170

The Bottom End

The heart of this supercharged Hemi is another 6.2-liter cast iron engine block, but this block features unique machining for the new billet main caps and stronger main cap fasteners, leading to 44% more load clamping ability than the Redeye bottom end. Since the Demon 170 creates around 32% more cylinder pressure at peak power, more than 2,500 pounds of pressure, the engineers made sure that the bottom end could withstand all of that force. The main and rod bearings now feature an upgraded copper-lead design to handle the extreme cylinder pressure.

Dodge Challenger SRT Demon 170

As you might imagine, all of that cylinder pressure is hard on the moving parts in the bottom end, so the pistons, connecting rods, crankshaft, connecting rod pins and the fasteners that hold everything together in the Challenger SRT Demon 170 engine have all been upgraded as well. On the front end of the crankshaft is a new fluid damper to help cut down on torsional vibration.

Powerplant Similarities

While everything other than the camshaft inside of the 2023 Dodge Challenger SRT Demon 170 engine has changed or been revised, there are some components that are shared between the Redeye and the Demon 170. Both cars feature the SRT Power Chiller, which uses the air conditioning system to cool the intercooler, greatly reducing engine intake air temperatures (by up to 45 degrees Fahrenheit) and the Race Cool Down mode.

Dodge Challenger SRT Demon 170

Both engines also use the same exhaust system design, so the Demon 170 sounds a great deal like the other supercharged Challenger models.

Dodge Challenger SRT Demon 170

2 thoughts on “How the Demon 170 Hemi Differs from the Redeye Hemi: Deep Dive”

  1. I wonder how much the development of the modified engine cost Stellantis, and how profitable they’ll be in only selling a limited number of them. Of course, it’s a pretty expensive car, so I guess their business case is likely sound. Still, all the changes you describe aren’t cheap from the engineering standpoint nor the components standpoint. It would be interesting to know how it all works out financially for them.

    • Well, if we assume a very low average selling price of $100,000 (that is based on MSRP, not MSRP+ADM), 3,000 US models leads to $300 million in gross receipts, so these cars will bring in a pretty decent chunk of change.

      The other thing to consider is that the initial Hellcat engine that was launched for the 2015 model year had a breakeven point on the engine development of about 5,000 units. They have sold over 100,000 of those engines, so it could be said that the original Hellcat has covered the development of this engine.

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