High-powered Hellcat Redeye engine a model of innovation

by Jim Kerr . Apr 05 2019
FCAThe 2019 Dodge Challenger SRT Hellcat Redeye is capable of sub-11-second quarter-mile runs.

FCA

The 2019 Dodge Challenger SRT Hellcat Redeye is capable of sub-11-second quarter-mile runs.

Each fall, a group of technically savvy journalists (some may call us gearheads) from the Automobile Journalists Association of Canada (AJAC) get together to hear presentations from the automotive industry on new technologies and innovations in the auto industry.

This year, 30 entries were pared down to the top 12 — with four in each category of safety, innovation and green technologies. These 12 were presented to the panel members, with the winner in each category announced at the Canadian International Auto Show in Toronto.

Here is one of the entries presented to the panel: FCA (Fiat Chrysler Automobiles) presented its 2019 Dodge Challenger SRT Hellcat Redeye powertrain in the Innovation Category.

The Challenger SRT Hellcat Redeye must be known by every drag-racing fan in North America. With 797 horsepower in the Redeye version — 717 hp in the regular SRT Hellcat — the Hellcat Redeye is capable of sub-11-second quarter-mile runs. That is quick for a race car, but this is a car that has a factory warranty and can be easily operated on the street.

There are several features of the Hellcat Redeye to help produce that power and maintain reliability. To increase maximum engine r.p.m., the valve keepers were designed with a single groove rather than the standard three-groove keeper. This aids in stability of the valve train. The valve springs were also redesigned, with a damping coil on the spring moved to the top of the spring. This enhances durability and damping of vibrations in the valve train. The camshaft was changed from a ductile iron shaft to a gun-drilled 5150 steel shaft with induction-hardened cams to handle the higher loads.

Power requires fuel, and to ensure adequate fuel delivery, the Hellcat Redeye uses a dual fuel-pump system so that at full throttle, and with the fuel injectors open 90 per cent of the time, both fuel pumps can maintain full fuel pressure. At idle and low-throttle openings, fuel pressure is reduced, with only one fuel pump operating.

The Challenger hood was redesigned with twin hood scoops to aid in vehicle stability and allow cooler air to the engine. The open airbox system with cold-air induction pushes more dense air into the supercharger and helps produce more power. Simply going from a rainy day to a sunny day can equal a 50-hp loss because of higher air temperatures, less dense air and less humidity. That is why the top drag racers constantly monitor drag-strip air temperature, barometric pressure and humidity, so they can tune their cars for the most power.

The heat produced by the Hellcat Redeye is amazing. At full power, there is enough heat to heat around nine homes. To control this heat and let the coldest air into the engine, the Hellcat Redeye uses three heat exchangers for heat rejection. The radiator and cooling system are the primary methods of getting rid of engine heat. But the intercooler on the supercharger is also used to cool the air as it enters the engine.

The third method of controlling the heat utilizes the air-conditioning system. When the vehicle is in track mode, the air conditioning system is switched from cooling the vehicle interior to cooling the coolant circuit located in the intercooler for the supercharger, which is mounted in front near the radiator. This cools the engine’s intake air by about 10 C, which increases the air density to produce more power. To accommodate this two-phase air-conditioning system operation, the AC compressor has been increased about 10 per cent in capacity.

This is innovation at its best, using existing components to perform additional tasks to produce better performance.

james.kerr@sasktel.net