Hi,
I've enjoyed my new PV Lusso I purchased from Vaneli's. It's been a month and I am pulling some great shots. I watched Peacecup's video and he does three pulls and gets a double, I believe - (not including his pre-infusion pull.) I can get a nice 2 oz double with two pulls,
The volume in the cup depends on the fineness of the grind as well as the dose (fullness of the basket). I grind fine and dose full (15 g) double baskets, and I only get 0.5 oz per lever pull - I usually take two or three pulls, lately mostly two. These result in very rich
ristrettos (15g per oz is a high coffee:water ratio).
The Ponte Vecchio group has a small vent hole near the top on the boiler side - when the lever is pulled down with a full portafiler once can hear air escaping as water fills the piston chamber. The longer the lever is held down the more water enters the group - the speed at which it fills is affected by boiler pressure.
I use a "Fellini" pre-infusion lever pull technique, first described on HB by Dr. Jim - this is a full downward pull to allow water to enter the group, followed immediately by a partial raise of the lever to force this water into the puck. The lever is then pulled to the bottom again for a traditional pre-infusion. The whole process takes approx. 10 sec, the commonly cited pre-infusion time. In my opinion, the Fellini pull results in a more complete pre-infusion, and therefore a more even extraction. To illustrate just how finely I normally grind, I never see a drop of coffee in the cup during the entire pre-infusion - if I do I usually grind finer the next time.
I have often wondered how the differing pressure profiles of multiple vs. single pulls affect flavor in the cup, but I have never had a chance to use a lever with a larger group. I can say that I prefer the flavor of my home-brew to the VAST majority of espresso I get in cafes, even by some well-qualified baristas. Therefore I conclude that multiple pulls can't hurt too much....
PC