E61: The secret behind the chrome cylinder head - Deep Dive

Deep Dive E61: The secret behind the chrome head

You've opted for a machine with an E61 brew group – perhaps an ECM, Rocket, or Lelit? Then you have a piece of espresso history in your kitchen. The E61 was developed in 1961 by Ernesto Valente for the Italian manufacturer Faema and fundamentally changed the way espresso is brewed.

But why does this chrome-plated head weigh almost 5 kilos? Why does it take so long to get it ready for use? And what exactly happens when you flip the lever? At the Coffee Coaching Club in Bern and Zurich, we'll explain the mechanics to you so you can feel them the next time you make a cup.

Act 1: The Preparation – The Thermosiphon

Before you even think about coffee, the E61 is already at work. The secret to its legendary temperature stability is the sheer mass of chrome-plated metal – and an ingenious, purely physical cycle.

The brew group is directly connected to the hot boiler via two copper pipes:

1. Ascent: Hot water rises from the boiler through the upper pipe into the hollow head of the brew group. Hot water is less dense than cold water – it rises on its own.
2. Heat transfer: In the brew head, the water transfers its heat to the solid brass construction. This takes time – hence the 20 to 30 minute heating phase until the entire head is at operating temperature.
3. Return flow: The slightly cooled water becomes denser and heavier. It sinks back through the lower pipe into the boiler, where it is reheated. This cycle runs continuously as long as the machine is on.

Act 2: The connection starts – The cam controls everything

You flip the lever. What looks like a simple movement from the outside is actually a precise mechanical interplay inside. The central component: the eccentric shaft (cam).

The cam is a metal rod with an asymmetrical profile – not a uniform curve, but rather deliberately raised bumps. When you turn the lever, this shaft rotates, and its bumps open or close various valves. A single lever thus controls the entire water flow: inlet, pre-infusion, and pressure relief.

Lever fully up: Pump starts

1. You fully flip the lever. A microswitch behind the lever activates the pump.
2. At the same time, the cam pushes open the upper intake valve .
3. The hot water from the thermosiphon circuit flows under pump pressure into the center of the brewing group – through a small nozzle element (gicleur) that already slightly restricts the flow – and then towards the coffee puck.

Act 3: The Heart of the Matter – The Mechanical Pre-Infusion

This is where the taste comes into play. This is why E61 espresso has this characteristic smooth, full-bodied character.

If the full 9 bar pump pressure were to hit the dry coffee grounds immediately, cracks would form in the puck (channeling) – and the espresso would be weak and unevenly extracted. The E61 prevents this with a built-in "soft-start" mechanism that works purely mechanically.

The detour of water:

1. The water flows not only to the coffee, but also simultaneously into a small, hidden chamber in the lower part of the brewing unit – the pre-infusion chamber .
2. This chamber is sealed off by a spring-loaded valve. As soon as the pressure in the brew head reaches approximately 1.5 to 4 bar (depending on the spring design), this valve opens and the water fills the chamber.
3. This is the crucial mechanism: as long as this chamber fills and the spring provides resistance, the pressure on the coffee grounds builds up only slowly. The coffee grounds are gently moistened, swell, and "repair" minor imperfections in the puck.
4. Only when the chamber is completely filled can the pressure rise to the full 9 bar. The actual extraction process under full pressure then begins.

All of this happens purely mechanically in the first 4 to 8 seconds of your extraction. You can often hear it because the pump runs a little quieter at the beginning and then audibly "engages".

The finale: Lever back – pressure release

Your espresso is ready, you put the lever back.

1. The pump stops (microswitch is triggered).
2. The cam rotates back. The upper inlet valve closes immediately – no new water flows in.
3. At the same time, the cam pushes open the lower exhaust valve (pressure relief valve).
4. The residual pressure that remains in the portafilter above the coffee puck escapes downwards into the drip tray. That's the typical hissing sound you hear.

This ensures that you can safely remove the portafilter immediately. The coffee puck is relatively dry – no hot water splashes when removing it.

All E61 features at a glance

• Solid brew head made of chrome-plated brass (approx. 4 – 5 kg)
• Thermosiphon circuit for passive temperature stability
• Mechanical pre-infusion via spring-loaded chamber
• Cam control: One lever controls all valves.
• Pressure release during shutdown – clean puck, safe release
• Purely mechanical system – no electronics in the waterway
• Standardized 58mm mount – compatible with a wide range of accessories
• Proven technology since 1961 (patent by Ernesto Valente, Faema)

E61 brew group: Technical overview

Who is an E61 machine suitable for?

The E61 is the right tool if you're looking for a classic, full-bodied espresso. Round, viscous, with a deep body and chocolatey notes. If you celebrate the ritual – flipping the lever, feeling the mechanical feedback, hearing the hiss as the pressure releases. And if you're prepared to set aside 20 minutes for warm-up in the morning (or use a timer).

In combination with a high-quality coffee grinder and our roasts such as Cozy Chocolate or Nutty Delight, the E61 fully demonstrates its strengths: The gentle pressure build-up emphasizes precisely the chocolatey, nutty notes that characterize these roasts.

Do you need more temperature precision, shorter heating times, or electronic control? Then take a look at our machines with saturated brew groups (La Marzocco) or the Arkel Coast – different philosophy, different result.

Experience E61 machines at the Coffee Coaching Club

In our showrooms in Bern (Gerberngasse 44) and Zurich (Hagenholzstrasse 50b), you can see E61 machines from ECM, Rocket, Lelit, and other manufacturers in person. Try out the lever yourself, feel the mechanics, and compare the espresso to that of a La Marzocco Micra . When you purchase a coffee machine for CHF 1500 or more, you'll receive a free 60-minute barista workshop with us – so your first shot at home will be perfect.

Frequently asked questions about the E61 brew group

The massive brass group head (4-5 kg) needs to reach full operating temperature. This takes 20 to 30 minutes. The advantage: Once hot, the E61 maintains an extremely stable temperature – even during multiple consecutive brewing sessions. Many owners use a timer so the machine preheats automatically in the morning.

Yes. The mechanical pre-infusion is very forgiving of minor errors in tamping and grind size. The gentle pressure build-up compensates for slight unevenness in the puck. This makes the E61 a very forgiving platform – especially if you're still fine-tuning your workflow.

A good espresso grinder is essential for any portafilter machine. For E61 machines, we recommend at least a solid single-dose grinder. Depending on your budget, the Varia VS4 , the Option-O Lagom , or a Weber Workshops grinder are ideal choices.

Neither – it depends on your priorities. The E61 delivers a smoother, rounder espresso with more body and is more forgiving of mistakes. The saturated brew group offers greater temperature precision, faster heat-up time, and clearer flavor separation. The best way to experience it is to visit our showrooms and compare them directly in the cup.

Roastery tip

The E61 group head is perfectly suited for medium to dark roasts. Its gentle pressure build-up emphasizes body, sweetness, and chocolate – precisely the strengths of our Cozy Chocolate and Nutty Delight blends . For nutty depth , Very Nutty is particularly impressive on an E61. If you'd also like to try light, fruity roasts: the E61 can handle it, but a machine with a saturated brew group will bring out the delicate fruit notes even more clearly.