Is A 1.5-liter Firefly Engine (GSE) In The Works?


Mopar Maniac
Staff member
May 23, 2018
United States
Is A 1.5-liter Firefly Engine (GSE) In The Works?
Evaluating The Rumors From Around The Web...
by @Bili

FCA Italy powertrain team presented a new generation of turbocharged engines during this year’s Vienna Motor Symposium.

These engines, known collectively as the Global Small Engine (GSE) family, were presented in 1.0-liter 3-cylinder and 1.3-liter 4-cylinder variants. Both engines feature the highly innovative MultiAir III technology, providing a much wider operation and better response compared to the last generation of MultiAir technology.

By implementing specific intake and exhaust cam profiles, low-load efficiency is improved by recirculating the exhaust gas by opening the intake valves in advance, while the high-load output is improved at the same time by delaying the intake valve closing. In other words, MultiAir III technology can reduce the real compression ratio, controlling knock and substantially improving fuel efficiency when the engine is delivering high power.

They also announced the development of a twin-scroll turbo version of this engines. Of course, a twin scroll turbo can be applied only on engines with an even number of cylinders, which leaves only the 4-cylinder variant of GSE as the possible application for this technology.

However, currently, there is no twin-scroll turbocharger for an engine which is smaller than 1.5-liters in capacity. A twin-scroll turbocharger is an ideal choice for a turbocharger on an engine of this size because it offers better responsiveness at lower RPMs.

Lately, we’ve heard some whispers about 1.5-liter GSE under development for Alfa Romeo. This engine could be extremely important for the European market where Giulia’s competitors like Mercedes Benz C-class, Audi A4, and BMW 3 Series all offer 1.5-liter gasoline engines. Making this engine even more important is the eventual demise of the diesel engine in Europe.

Engines in the GSE family are very compact. They have 77mm bore spacing and 70mm bore. That’s pushing the limits for what is possible on an HPDC engine block with steel liners. Currently, 71mm bore is the biggest they can achieve with steel liners, so this rumored 1.5-liter engine would have a very long stroke of 94.5mm or 97mm to achieve 1.5-liters of capacity.

We don’t know if the company will seek power or efficiency out of a potential 1.5-liter GSE powerplant. Currently, both GSE and GME in their most powerful versions have power around 135-140 HP per liter and a torque numbers around 205 Nm (151 lb-ft) per liter. A 1.5-liter GSE could very likely have around 205 HP and a 310 Nm (229 lb-ft) of torque.

One competitor is offering a belt driven mild hybrid system with their 1.5-liter gasoline engine. Alfa will likely produce a similar solution. Belt-driven mild hybrids are in the Alfa Romeo 5 year plan, so this engine could benefit from that technology, currently known as eTorque on the Jeep Wrangler JL equipped with the 2.0-liter turbo and the 3.6-liter Pentastar V6 2019 Ram 1500.

A lot remains in question about this engine, but the benefits it would provide Alfa Romeo are numerous. It will allow Alfa to better compete with German luxury brands that already offer similar engines. Stay tuned to Mopar Insiders for more information on this engine.


May 31, 2018
The 1.5L Firefly would be a good upgrade for the next 500 Abarth (whenever it's coming out :mad:)


Active member
Sep 19, 2018
I’d have thought they’d go with an e-turbo for several reasons:
  1. Already running the necessary 48v system for the eTorque BSG
  2. Low end torque
  3. Instant boost
  4. Flexibility seems to mesh well with the MultiAir III intake system
  5. The only real drawbacks I can see might be cost and increased size of 48v battery system


Active member
May 4, 2018

We'll see. Currently I'm not so sure that we will see a 1.5 liter engine. Yes, it sounds like a likely development.

Twin scroll turbo fits perfectly into the story. As I have written. In current catalogues there is no twin scroll turbo suitable for an engine smaller than 1.5 liter. Of course it must be a 4 cylinder, or have a even number of cylinders to use such technology.
FCA Italy team during a presentation said that they are working on twin scroll version of GSE/Firefly.

So I just connected a couple of dots.

Back in the past there was a 1.5 liter Giulia in spare parts catalogue. Last week I have heard new rumors about 1.5 liter FireFly for Alfa. So...

What sounds unlikely? This engines are very compact with very small bore spacing, with a tiny bore. But turbocharged engines are in love with a long stroke. But for 70 mm bore they must go with a very long 97 mm stroke. That could add a lot of friction.

E-turbo or E-Booster? Yes that's an interesting solution especially if it's paired with a P2 48V MHEV architecture. As we know P2 could give an all electric mode. Current E.Torque can't do that.

And don't forget that E.Torque and similar systems will be exclusive for a RWD based cars.
For FWD like Renegade P2 48V MHEV is previewed but not before 2021. And I believe that a Renegade will not use a GME.
Batteries for P2 48 MHEV could go up to 2 kWh. Compare it to Toyota's full hybrids from few years ago.


New member
May 17, 2018
I don't know much about engines but why do you have to have an even number of cylinders?

They also announced the development of a twin-scroll turbo version of this engines. Of course, a twin scroll turbo can be applied only on engines with an even number of cylinders, which leaves only the 4-cylinder variant of GSE as the possible application for this technology.

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