Nuova Simonelli Oscar - Post Mod Report

Need help with equipment usage or want to share your latest discovery?
Bezman
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Posts: 78
Joined: 12 years ago

#1: Post by Bezman »

Many months have passed since I last posted here. In this time my espresso making technique improved much, to the point where I felt I was limited by my machine - a stock Oscar.
I thought about installing an OPV and a vacuum breaker myself, but after checking with a local shop, I got it done by professionals for a fair price.

After checking the machine, they told me my original CEME pressurestat is acting up and should be replaced. They put a MATER instead. The guys at the shop told me they set the boiler pressure to 1.2 bar and the OPV to 8.5 bar.

I didn't like the low (for an Oscar) boiler pressure, when pulling back-to-back shots, all shots but the first came out cold even without a cooling flush. I went to a hardware store and got a basic pressure gauge and all the needed fittings and raised the pressure to 1.4 bar (at the top of the cycle, 1.2 bar at the bottom). This same pressure gauge at the portafilter showed 9 bar. Unfortunately the gauge is 0-10 bar, so it's not very accurate at the low range. I'll order a 0-2 bar on ebay and measure again when it arrives.
Can't say right now how much the shot quality has improved, but the biggest change I noticed is that I can now use a much wider range of grind-dose settings while getting a very acceptable shot in return. Thank you OPV!

Here is a photo of the pressure measuring setup. Sorry for the quality - phone camera and shaky hands.