I am seeing some confusion about the engine in the 4C, mostly in regards to the differences from the Euro 5 to Euro 6 engines. So, I thought I would clarify this, and spell out the differences.
To start with the engine in the 4C is officially called the "B TC 1.8 Di Turbo Jet Euro 6". For reasons that should be obvious, I refer to it as the 4C engine.
There have been many "1750" engines in Alfa's history, and the two most recent, the Euro 5 and Euro 6 engines are often confused.
Let me start by making something very clear. These are two DIFFERENT engines. Don't let anyone tell you otherwise. No car ever sold in the US has the Euro 5 engine. In Europe some versions of the Giulietta pack the 232hp Euro 5 1750, but that is NOT the engine we have in our 4Cs. We have the Euro 6 engine.
So...what's the difference? Pretty much everything. While some parts interchange, they are two different engines.
1. The block is different, and not just slightly, they are totally different designs. The 4C engine has a fantastic 2 piece block design, which I'll talk about more in a tech article on the subject. The Euro 5 engine has a very good, but largely conventional block.
2. The cylinder heads are different. Specifically, the 4C's Euro 6 engine has different intake ducts, exhaust ducts and combustion chambers.
3. The oil/vapor separator's spring calibration is different. This matters because the parts look as if they interchange, but they do not. The separator on the 4C engine is specific to the demands of this engine.
4. The wastegate operation is completely different.
5. The high pressure fuel pumps are different. As with the separators, they look as if they would interchange, but the pumps are different internally.
6. The fuel injectors are different.
7. The crank position sensors are different types. The 4C uses a Hall Effect sensor vs the Euro 5's inductive type. They are also located in different positions on the two engines. (I am glad we have the Hall effect type).
8. The O2 sensors are different, and again, do not interchange.
9. The oil cooler configuration on the 4C engine is different, and in my view superior.
10. The thermostat is electronically controlled by the ECU in the 4C and not in the Euro 5. That's can be an advantage in certain tuning situations, and it's just generally better at controlling coolant temps than the older methods.
So there you have it, all the key differences between the 4C's Euro 6 engine and the Euro 5 engines.