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Discussion Starter #1 (Edited)
Getting ready to rebuild my motor. Bought a 2012 mini cooper S with a broken rod at 65,000 kms. Suspect the rod bolt had incorrect stretch, since its assembled with torque plus degree turn procedure. I could mention the pitfalls of that technique, but in short measuring actual rod bolt stretch is the only reliablw method. Usually 0.0055 to 0.006" rod bolt stretch is the norm.

Anywho, i got the motor out of the car and completely disassembled. Surveying the motor damage and what i can improve upon it. The engine block is garbage since the one cylinder is gouged enough from the rod breaking 2" above the big end. Could go 2mm over custom piston to get rid of the damage, but im not that vested into the car.

I noticed alot of oil, which is from the valve seals and most likely the crankcase breather. The piston ring gap would warrant that oil in the back of the valve or chamber.

The intake port in the bowl area is embarrasing terrible. WOW! What a pile of coal. The roof side of intake port has this drop off just before it enters the throat. And the floor of the port in the bowl is just as bad with a ski jump. I'll be re-arranging the port floor with epoxy to create a crest before the valve leading and shape a gentle radius leading up rite up the throat. And fully utilize the cross sectional area of the throat.

The chamber is heavily shrouded on the intake side. Unfortunately the shrouding on the outside is close to the headgasket, so not much i can do. But the inside will get a good amount of unshrouding, also the intake valve pockets on the piston will get the walls laid back a bit to unshroud also.
Piston acts as a floor at and near TDC on intake stroke.

Ill be adding a manual chain tensioner to get rid of any cold start/low oil pressure timing chain slap. Which creates the eventual demise of the cheap plastic chain guide.

Removing 1 leaf from the headgasket to tighten up squish. Balance and polish the beams on the stock rods. Add a coating to the skirts of the pistons.

Overall just make a better engine. I really think those stock intake ports are hindering this motor. 180hp from turbocharged 1.6L is anemic. Should pick up 35hp at the same boost level.

Picked up KTAG/KESS to tune it after. And see how hard i can lean on it.

I dont want a tire shreader, just a good well mannered car.

Hopefully my ports should maintain good driveability at low rpms and behave like a naturally aspirated car, while having great peak power.

In my opinion linear power delivery makes for a fun car.

P.S. This is my first Mini, and first passenger car in 13 years. Should be fun.

Ill post pics of the porting, engine build and all the good bits if you guys want.
 
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