I have always felt that lever machines are special but aside from aesthetics, I am having trouble understanding how it differs from a pump machine. Specifically, here is the pressure (red) and flow (black) profile for a dual spring setup provided with the Smart espresso profiler app.



And this is the corresponding plot from my E61 machine (Quickmill Anita).



The E61 machine gives a declining pressure profile because of the decreasing puck resistance. I would suspect the in the case of the lever, it is the same thing. So the decreasing force of the spring probably doesn't have an effect. So shouldn't I be able to get just as good a shot from an E61 machine as from a lever machine? If not, what is different about a lever machine?

I found with a rotary pump E61 the pressure from the pump was constant. With a pump the water flow started and ended with the set pressure after a bit of preinfusion pressure build up on the E61.

With a spring lever I think the extraction dynamics are different. A large group has to fill first at either line pressure if it's a plumbed in HX or boiler pressure if it's a dip tube. That's a good bit of preinfusion you can hold for as long as you want before letting the lever go. Spring pressure on the piston then compresses the volume of brew water at a declining pressure from there. What you allowed to fill the group is the extraction volume you'll get unless you do fellini moves which if you do changes extraction parameters more than I think a pump machine would be capable of without extraction flow or pump pressure control.

I got pretty good extractions with a simple plumbed in rotary pump E61 HX. With a commercial group lever the extractions are a lot better with more character than an E61. I credit that to different control and extraction dynamics of the spring lever compared to the pump E61.

I am not equipped to give a scientific or measurable reason why lever group js better than an e61 pump except just now their coffee taste like to me. All I can say is that my Nurri Leva produces espresso that I find to be more tasty than that produced by my e61 by a significant margin.

Flat 9-bar makes for nice carbonation fizz that tastes amazing in the cup. I try to replicate this with my La Pavoni and I can't wait to receive my pump machine, a Micra. I've tried shots from commercial levers too and they always disappoint. It's like drinking a concentrated pourover, but some people like that I guess. The E61 is probably the single best thing to happen to espresso.

I believe there is also a big taste difference between E61 pump machines and pump machines with a saturated group, like La Marzocco, Synesso, Slayer and KvdW. These last ones bring out roasters taste notes that I can't get with spring levers.
(from light roasts).

Spring levers slam the puck the initial flow at the start is so much more than a pumped machine.

What dual spring lever did you use for the test?

If you look how quick you get peak pressure with the spring Vs the pump machines much slower ramp.

The bigger advantage of a lever to me is the silence.No pump noise.

NelisB wrote:I believe there is also a big taste difference between E61 pump machines and pump machines with a saturated group, like La Marzocco, Synesso, Slayer and KvdW. These last ones bring out roasters taste notes that I can't get with spring levers.
(from light roasts).

Never tried one of these.Expensive.Would love to though.

The grouphead design in general is different. Offen in levet Machines the dispersion screen presses the puck together which is why for many levers only a light tamp is necessary. In a pump machine there is usually clearance between the screen and puck.