Wow, that's a brutal lesson learned! I feel your pain on the engine carnage. 25psi is definitely pushing it. 18psi sounds safer for a stock S, but every engine is different. Dialing back boost can be tricky, the wastegate adjustment should have an effect. A dyno tune is probably essential, especially with that turbo. For a bit of mindless fun while you wait, maybe check out Crazy Cattle 3D on your phone. I don't know any specific shops in Philly, but a reputable tuner is key. Good luck!

Given your engine blew up from overboost, you're right to be cautious. For your 2011 Mini Cooper S (R56), 18psi is generally considered the safe maximum boost for stock internals; 25psi is dangerously high and will likely cause another failure. You cannot reliably or safely dial back boost mechanically on this engine; the car's ECU, designed for the smaller stock turbo, is commanding too much boost for your K04 GT Dominator. A custom dyno tune is absolutely essential to correctly program the ECU to target a safe boost level, adjust fueling, and optimize timing for your specific turbo. For tuning shops in the Philadelphia area, Helix Motorsports (Philadelphia, PA) and Technik Competition (Malvern, PA) are highly MyCentura portal recommended for their Mini/European car expertise and in-house dynos. Until tuned, avoid high RPMs and boost. 

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"jennifera" is a SPAMMER

I went through something similar with my Mini Cooper S a few years ago. After upgrading the turbo, I didn’t realize how much extra boost was coming through until I started hearing knocking sounds. I found that without proper tuning, the engine could easily get damaged. One thing that helped me was using a game like Snow Rider 3D—oddly enough, it gave me a better understanding of throttle control and boost management in a fun way before committing to real car mods. Definitely get a professional tune to safely enjoy your upgrade!

Hey all.  Complete n00b to boost.  I have a 2011 Mini Cooper S.  Over the years, I've put some easy plug and play mods on the car, (Intercooler, stiff rear sway bar, piggy back chip, etc.)  After a while, I REALLY wanted to go fast, and so I swapped the stock turbo for a
K04 GT Dominator.  I didn't really see anything in that article that warned that this thing would make too much boost out of the box. 

Well lesson learned. 
I think within 100 miles the number 1 cylinder absolutely disintegrated and blew out 2 holes on either end of the crank case.

1 short block and almost a year later, I put a new engine in the car, same turbo and all.  This time around, I would like to make it so that this turbo does not completely blow up my engine hahaha.  I've installed a boost gauge, and did a couple runs in 3rd gear and saw that at ~5000rpm, the car is making about 25psi of boost with no signs of it being limited whatsoever.  From what I've read, some stock JCW could handle about 21psi or 22psi of boost.  The consensus around various online forums seems to be that stock Cooper S's can handle 18psi safely.

So 3 questions:

1. Does 18psi sound correct? or am I going to blow up my engine again? What kind of boost are people running on their R56 S's? 

2. How does one actually dial back the boost? I've tried loosening the two lock nuts around the waste gate actuator and dialing that way back, but nothing seems to have changed.  Is this something that is gonna have be mapped on a Dyno?

3. If the car needs to be tuned on a dyno, does anyone know of a good place to go in the Philadelphia area?

Thanks in advance for any and all advice.