# What's the relationship between pump pressure and coffee recipe / ratio?



## Dodds25 (Dec 19, 2019)

I have a Barista Express, which I think is factory set to 14 or 15 bar. Obviously the machine is billed as an espresso maker, but the manual recommends a ratio of about 3.5:1, which is well into lungo territory as far as I'm concerned. I do find I get the best results around there though. If I go shorter, and the pressure rises towards the machine limit, then no matter how careful I've been with the puck prep I get a lot of channelling. I put this down mainly to the pressure, although obviously you can't expect too much from a grinder that's built in to a £450 machine. Is it fair to say that a machine with a higher max pressure is better suited to longer drinks?

I'm thinking of adjusting the OPV but want this to be a one-time thing really. I don't want to be constantly taking the thing apart and putting it back together because I have a long track record of breaking things that way.

AFAIK the standard pump pressure for espresso machines is 9 bar. I guess that's based on a more traditional espresso ratio of about 2:1.

Does it follow that if you want to pull ristrettos, you ideally want a pressure of less than 9 bar?

Is it realistic to adjust the BE to below 9 bar, or is the valve just going to be open all the time if you set it that low (and are going for maybe 1.5:1, so grinding very fine)?


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