Now that was interesting. The pump started shot kept that higher pressure for quite a while once the spring took over, but without the pump it never hit a pressure level as high. I would have thought that spring pressure would be the same whether started by the pump or not.

Air in the chamber... With the pump pressure the air is more compressed and more water enters, then you can take more advantage of the spring compression.

Yeah, taking a second look at both videos I see nearly identical pressures from the lever when in the same position on both shots - as one would expect. The more compacted spring pressure point is able to piggy back on the pressure buildup from the pump early in the shot it seems, then as the lever moves along you see less pressure just like a normal lever pull.

Hmmmm... I need a winning lottery ticket so I can start a lab...

Tripax wrote:I created a manometer portafilter and created two movies of the pressure profile. One with and one without pump.

Thanks Nick. Great looking manometer setup.

Vlad, a Milwaukee HBer who uses a an old Faema Urania says the higher pressure preinfusion can be emulated on lever machines that have no pump boost by lifting the lever, and holding it steady at the point where it catches, so the flow is interrupted, but the pressure is maintained.

He didn't have a needle valve/manometer setup; so I was wondering if you could check if that's true (no need for a movie).

Hi Nick, great videos! Like Jim said, I on occasion use higher pressure preinfusion on my Faema by putting the lever down for a few seconds to fill the group, raising the lever to the catch point and holding it there for the length of preinfusion. My best guess is that I am preinfusing at around 7 bars instead of 1. The result is a denser, thicker shot. On my machine and my grinder using the same grind level, it means I have to updose the basket 2 grams.

Here is a post describing this technique: High Pressure Preinfusion Without a Pump

I would love to see a video with you simulating these conditions!

Not sure if that worked, the pressure does not seem to hold when I stop the lever (because the flow does not stop).

vberch wrote: Like Jim said, I on occasion use higher pressure preinfusion on my Faema by putting the lever down for a few seconds to fill the group, raising the lever to the catch point and holding it there for the length of preinfusion.

So you are lifting the lever until the spring engages & Pre infusing at that initial spring pressure?

That's correct.

I wonder why it didn't hold? I don't think it worked.

Tripax wrote:Not sure if that worked, the pressure does not seem to hold when I stop the lever (because the flow does not stop).

It's possible to just hold a cloth over the outlet on the Scace device to simulate pre-infusion. It doesn't take much to block the flow.