It was a very profitable tour, we got out of it exactly what we wanted to.Steve Spooner
The Under-18s clinical finishing and defensive resolve saw them to victory.
Leo Brown (two), Josh Andrews and Jordan Clarke got the goals as Blues came from behind to win.
Following on from a 2-1 success against Vitoria de Guimaraes, it rounded off nicely the pre-season camp.
"It was an excellent week," confirmed Lead Professional Development Coach Steve Spooner. "We were really, really pleased with the application of the players and the way they behaved on and off the pitch.
"They had three training sessions the other day and put everything into it, and that was typical of their approach.
"It was good to finish with a win and it was a different type of game to the other one, against Guimaraes.
"We seemed a little bit apprehensive at first, as it was Porto. When we settled down we wasted possession too easily and our passing was too slow.
"We went a goal behind but once we picked the tempo up we did a lot better."
Under-16 Andrews equalised for Blues, a poacher's goal after a cross into the area came back off the 'keeper.
"We were on the back foot for 15 - 20 minutes of the second-half," Spooner continued. "But we scored on the counter attack through Leo Brown and then we had to be resolute, keep our shape."
Clarke made it 3-1 when he used his pace to break down the side and Brown added Blues fourth goal by going round the 'keeper and finishing from a tight angle; he also hit the post in the first-half.
"We have been working on pressing high but this was also a case of knowing when to defend deeper, when to block the space and when to commit to go for the ball, when you are under pressure.
"Ironically we didn't play as well as the first game and didn't have as much possession, we weren't as productive with the ball, but the difference was that we took our chances."
Blues flew back to England on Sunday afternoon to put the final touches to their preparations for the U18 Professional Development League campaign, which beings against Millwall at Wast Hills on Saturday, 12 August (noon kick-off).
"It was a very profitable tour, we got out of it exactly what we wanted to," reflected Spooner.