MINI performance tuning and rebuild

Initially the project vehicle, a 2004 MINI Cooper S was recovered and delivered to Waterfall Garage in Wimbledon, South West London.

MINI repair pickup for Waterfall Garage in Wimbledon SW19MINI performance tuning at Waterfall Garage in Wimbledon SW19

The strip down

Initial MINI engine diagnostic checks revealed a correlation issue with the timing which needed to be checked, so it was necessary to begin a strip down of the whole MINI engine.

MINI engine stripdown at Waterfall Garage in Wimbledon

Removal of the MINI’s intercooler and cam cover.

Removal of the MINI’s intercooler and cam cover

Fault finding

A compression test revealed a problem with low compression, so the MINI’s cylinder head was removed, revealing 16 bent valves.

MINI cylinder head removal

The timing check revealed that the MINI’s camchain had jumped.

MINI camchain repair in Wimbledon at Waterfall Garage
Engine removal

Due to the extent of this damage it was decided to remove the MINI engine completely and carry out a full rebuild.

MINI engine removal and full rebuild in SW19 at Waterfall Garage

This showed that there had been even further damage to the MINI’s big end shells, in fact the vehicle and been almost driven to destruction.

Damaged MINI big end shells

Damaged MINI big end shells and piston rods

MINI damaged big ends

Replacing the MINI’s clutch and lightening & balancing the flywheel

Whilst the engine was removed, it also made sense to replace the clutch kit and lighten and balance the flywheel. By doing this, a reduction of over 2 kgs was achieved between the original MINI flywheel and the lightened and balanced flywheel.

Original MINI clutch kit and flywheel

Replacement MINI clutch kit and lighten and balanced flywheel in Wimbledon South London

Reducing the crank pulley diameter

A further MINI tuning modification was to enlarge the crank pulley diameter by 2%, thus increasing the ratio on the supercharger.

Increasing the ratio on a MINI supercharger in SW19 at Waterfall Garage

The next image shows a layout of the replaced MINI parts.

Replaced MINI performance tuning parts

MINI clutch assembly.

MINI clutch assembly at Waterfall Garage in Wimbledon

MINI engine block honed for refit.

Honed MINI engine block

Machined MINI crankshaft.

Machined MINI replacement crankshaft
The result of the first stage of the MINI performance tuning

The end result is a measurable increase in the MINI performance, as well as a great improvement in the throttle response.

Next steps

The next phase of the MINI performance tuning will involve fittting:

  • New Exhaust – with 25% weight reduction and increased flow
  • MSD Ignition Coil Pack
  • Magnecor KV85 Spark Leads
  • DENSO Iridium Spark Plugs
  • GRS Motorsport Top-Mounted Intercooler

All of which will give a final likely increase in power from 175bhp to around 210bhp

If you’d like to talk to us about improving the performance or the economy of your MINI – give us a call on

020 8543 4799