Inside the “Firefly” or “T4” GSE 1.3 turbo engine

Years after Fiat and Chrysler came together, a team of engineers from nearly every part of the country, including Americans, Italians, and Brazilians, came together to create brand new small (GSE) and medium-sized (GME) four-cylinder engines. The acronyms stand for “Global Small/Medium Engine;” in Brazil, the GSE is marketed as the FireFly.

The first of the GME engines was the 2.0 turbo, which is used in rather different forms by Alfa Romeo and Jeep. The first of the GSE engines were a 1-liter and 1.3-liter turbo, producing 71-76 hp and 100-108 hp respectively. Both contain elements of past Fiat engines (e.g. the FIRE series which yielded the 1.4 Turbo of the Dodge Dart, Fiat 124, and Abarth 500) and Chrysler engines (e.g. the Neon 2.0, which was still, with many modifications, produced in Brazil, and the Pentastar V6). The 1.3 liter engine, coded T4, displaces 1,332 cc (1.332 liters).

T4 1.3 turbo GSE engine

Features of the GSE series include MultiAir III variable valve timing and a low-inertia turbo with an electronically activated wastegate (the latter having been produced by Chrysler since 1985). The MultiAir system uses solenoids and oil pressure to set valve timing and lift for each cylinder individually, and acts on both intake and exhaust; exhaust gas recycling is enabled by advance opening of the intake valves, while more power can be gained by delaying valve closure to increase compression.

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The 1.0-liter version, launched in 2016, is not available in the United States or Canada, and has been a Fiat exclusive. The 1.3-liter version is available, in essence, globally. A 1.5 liter turbo is reportedly just around the corner.

Jeep’s version of the 1.3 turbo boasts an impressive 177 horsepower at 5,500 rpm and 210 lb-ft of torque at 2,200 rpm. Debuting on the 2019 Jeep Renegade and Fiat 500X, the 1.3 FireFly Turbo engine (coded T4) was 20% more efficient than the old 1.4 liter FIRE engine; and was planned to be a foundation of upcoming hybrid-electric powertrains.

Renegade engine HP Torque MPG (FWD)
1.3 turbo (auto) 177 210 24/32
1.4 turbo (manual) 160 184 24/31
2.4 WGE (auto) 180 175 22/30

The new GSE engine replaces both the old Fiat 1.4 T4 and Chrysler 2.4 liter “World Gasoline Engine,” but with better fuel economy, though 91-octane premium fuel is recommended (as it was on the Fiat engine, while the Chrysler took regular gas). It has more horsepower and torque than the 1.4, and nearly the same horsepower as the 2.4 with far more torque and better mileage when packed into the same car.

Secrets of Fuel Economy and Power

The 1.0 and 1.3 liter versions of the GSE series are nearly identical, except for their control calibrations.

The FireFly has a 200-bar direct injection system, adding to fuel economy and performance. Peak torque comes at 2,200 rpm, which is 1,700 rpm lower than the 2.4-liter unit; the engine is also more responsive because the low-inertia turbocharger can spin up more quickly. The redline comes at 6500 rpm as used on the Jeep Renegade; the engine weighs in at 100 kg.

The third-generation Multiair valve timing system, which uses a solenoid-activated hydraulic system to permit the right amount of air to flow into the combustion chamber, is more accurate than before. The new turbo engine also warms up faster, thanks to an integrated exhaust manifold and an electronic thermostat. As with modern Rams, the system has a variable displacement oil pump. Coil-on-plug ignition is a natural, as is a “smart charger” alternator used on cars with stop-start systems; the alternator works while the vehicle is slowing down to reduce parasitic drag, and stops charging when more power is needed. Finally, the oil is 0W20 or oW30 to reduce friction; and alcohol-burning cars, mainly sold in Brazil, have heaters in the fuel rail for easier cold starting.

T4 firefly GSE 1.3 turbo engine

A relatively long stroke (86.5 mm, vs a 70 mm bore) increased low-end torque, while a timing chain cuts maintenance needs. FireFly engines without turbochargers use cam phasing, as the Chrysler Pentastar V6 does, to cut costs.  The block itself is cast aluminum, with cast-in iron liners (Chrysler’s solution for aluminum engines from the start).

The combustion chamber and valve setup is remarkably similar to that of Chrysler’s second-generation 4.7 liter High output V8, including the plug positions. The block itself has many carryovers from the “E.torQ” engine, originally based on the Neon 2.0, including the internally balanced crank rotating assembly. The integrated exhaust manifold is an evolution of the Pentastar Six’s setup. The open deck block uses an offset crank similar to those of the Tigershark WGE engines, to reduce piston-to-cylinder-wall loading.

To deal with the particulate emissions of direct injection engines, a particulate filter is placed behind the catalyst. The new engine conforms to Euro 6D rules (which are based on the Worldwide Harmonized Light Vehicle Test Procedure, or WLTP, and the Real Driving Emissions test).

Real-life reviewers have not been quite as full of praise for the engine, at least as it is in the Jeep Renegade. Car & Driver pointed out that it was slightly slower in 0-60 (9.0 seconds; 17.1 second quarter-mile) than the older Renegades with either engine choice. They found it felt a little more energetic, but there is still a delay before power comes on, and the low redline was an issue; and they were disappointed at the gas mileage, too.

Development and Production Sites

The FireFly was originally developed in Brazil by a global team led by Powertrain Coordinator Bob Lee and Powertrain Engineering Director for Latin America Aldo Marangoni. Bob Lee was in charge of engines and electric propulsion since 2011, and joined Chrysler in 1978, leading both the New Hemi and Pentastar V6 programs (he was likely also in the 4.7 V8 program). Aldo Marangoni had a hand in the MultiAir, FIRE engines, diesels, and the highly regarded TwinAir.

The modular architecture of the GSE series is based on the 333 cubic centimeter cylinder unit; from there, different blocks and dressings can be added. FCA integrated systems to make plug-in and mild hybrid versions easier to handle, and these have already come to fruition. The block was developed with Fiat’s Teksid division.

It is made in Bielsko-Biała, Poland, which attained the World Class Manufacturing Gold Level in 2012. The same plant, where the company has employed over 1,200 people, also produces the FCA’s 1.3L MultiJet diesel and the 0.9L TwinAir gasoline engines. FCA invested over €200 million for a state-of-the-art production line with a 70% automation level. Since the site became operational in 2003, it has produced more than 7.5 million engines.

Oil change

Changing the oil, at least in the Renegade/500X, requires 10 mm and 13 mm sockets, a T30 socket, and three and six inch extensions, along with an adjustable oil filter wrench. It takes four and a half quarts of synthetic oil 0W30; look for conformity to Mopar MS13340 or your owner’s manual to find the right oil.

If you do not have the Trailhawk, you can skip the skid plate instructions and you will not need the T30 or 10mm sockets.

  1. Put the vehicle onto ramps, pop the hood, and set the emergency brake; put transmission into Park or first.
  2. Take off the oil cap
  3. Remove the skid plate if you have one (TrailHawk model only); the perimeter has the 10mm bolts, with both the other sockets also needed.
  4. Find the drain plug, which faces the back of the vehicle.
  5. Place the drain pan carefully; the oil can shoot out by around a foot, possibly more, possibly less.
  6. Drain the oil by opening the drain plug (13 mm socket).
  7. Put the drain plug back.
  8. Take off the filter (it’s over the oil pan) and, if it did not come off on its own, the filter gasket.
  9. Lightly oil the new filter gasket; you can use the old oil for this.
  10. Put the new filter on; do not overtighten; use your hand for this.
  11. Refill the oil.
  12. Start the engine and check for leaks.
  13. Reinstall the skid plate, going in a rotation (don’t tighten one screw, then another; tighten each one a bit in turn, preferably going in an “opposite-sides-first” pattern).



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