bostonbuzz wrote:How are you getting the pressure throughout the shot? You u must have drilled a new hole juuust above the shower screen through the back of the group?

In short: For the manometer on the grouphead, I drilled a hole through the piston + rod, and I had to do some machining in the head to get 'to the ouside world'.
For the manometer in the front cover (+ pressure release), I removed the 2 bottom seals of the piston (only using the top one) and filled them up with teflon rings. Then I put 2 solenoid valves in the feed line, between the HX and the grouphead. One valve open/block the flow from the HX to the grouphead, and one valve release the pressure (into the drain).
Not sure if I would do all of that with a new machine, but ours is quite old and decided to take the risk. So far it's working ok...

I just fully understood what you wrote, thanks for the explanation. Quite a mod to change the bottom 1/2 of the piston!

I was wondering how you got a reading on the gauge and the solenoid to function given that the piston covers the water hole quite soon in the stroke. I just installed one on mine and it's really only useful for preinfusion. That makes sense that the hole being open all the time through to the portafilter would allow for that. The flush function would be important since the group water tube may have some coffee from the exhaust still in there, as there is no back-flushing a lever. Cheers.

I thought when lever down until the pump fill the group the pressure will go to 9 or 10 bar.. look like around 2 bar on you two videos.

Marcje wrote:... For the manometer in the front cover (+ pressure release), I removed the 2 bottom seals of the piston (only using the top one) and filled them up with teflon rings. Then I put 2 solenoid valves in the feed line, between the HX and the grouphead. One valve open/block the flow from the HX to the grouphead, and one valve release the pressure (into the drain). ...

That's a very impressive mod. Kudos.

Do you have any tips on making the hole in the machine's faceplate for the additional gauge?

Thank you! I used this drill and lots of lubricant.
It was a bit nerve wrecking to be honest...

Stephane_Paris wrote:I thought when lever down until the pump fill the group the pressure will go to 9 or 10 bar.. look like around 2 bar on you two videos.

The machine is plumbed and I was using the line pressure, not the pump.

Next useless, but fun mod: First step of connecting the Strega to a pressure monitoring dashboard/app.