# Londinium R PI Pressure



## Dunk (Mar 26, 2015)

I had a play this morning doing a little experiment with how PI pressure effects the taste.

So i pulled two shots back to back this morning. All 18g dose 7s PI time and 36g in the cup in 30-36s. Coffee Craft House Papua New Guinea. 18g IMS basket.

1 - PI pressure 2.5

Lack of taste, sweet but not body or real noticeable flavour, under extracted i suspect.

2 - PI pressure 4

Punchy, maybe a little drying but flavours coming through, slightly over extracted i think.

From this i put the machine to 3.8 bar PI. Kinda crazy how much it changes the shot.

Anyone else done this kinda experiment with their LR?


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## PPapa (Oct 24, 2015)

Does it need to be redialled in? I wonder if changing grind/yield makes a difference after a change in PI.

I'm yet to get a PI module for my LR. I'm just too uncomfortable taking it apart.


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## Dunk (Mar 26, 2015)

PPapa said:


> Does it need to be redialled in? I wonder if changing grind/yield makes a difference after a change in PI.
> 
> I'm yet to get a PI module for my LR. I'm just too uncomfortable taking it apart.


 Yes so at a higher PI i had a slightly finer grind to account for the added PI pressure


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## mctrials23 (May 8, 2017)

I want to play around with PI pressure a bit more but I can't be bothered to keep taking the case on and off whenever I want to do it. Not sure why the wireless module isn't available yet. Frans seems to have had it for about 6 months now and it looked like it was working fine.


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## Mrboots2u (May 10, 2013)

Dunk said:


> I had a play this morning doing a little experiment with how PI pressure effects the taste.
> 
> So i pulled two shots back to back this morning. All 18g dose 7s PI time and 36g in the cup in 30-36s. Coffee Craft House Papua New Guinea. 18g IMS basket.
> 
> ...


 At a 1:2 ratio it is unlikely you are over extracting no matter what the pre infusion pressure. By this I mean hitting over 20% EY.

This doesn't mean it isnt changing taste in the cup though , different flow rates and pressure infusions do have an effect. Same as brewing a shot at 4bar all the way ...

Remember most commercial pump machines are probably running at 3 bar pressure pre infusion in cafes ( NS etc ) .


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