1991 BMW 850i Stage III Twin-Turbo

Information for this Dinan 8 registry entry has mainly been sourced from an online auction in August of 2016.  Additional information will be updated as it becomes available.

General Information

Chassis Number: CB72129
Production Date: 09/26/1990
Mileage: 66,899
Transmission: Automatic
Owner: Unknown
Location: Joliet, Illinois, USA
Exterior Color: Calypsorot Metallic (252)
Interior Color: Pergament Nappa (0356)

Dinan Modifications


Stage III Twin Turbo Package

  • 5.6L M70 V12 conversion
  • Twin turbochargers (10psi), dual air-to-air intercoolers and associated piping, valves and wiring
  • HP exhaust system
  • Extrude honed intake manifolds
  • Engine electronics


Automatic Transmission

  • Transmission cooler
  • Transmission chip
  • High stall torque converter
  • 3.64:1 Limited slip differential


Stage III Suspension

  • Performance spring set
  • Custom valved shocks/struts
  • 27mm (F) and 17.5mm (R) adjustable anti-roll bar set
  • Front camber plates


Stage III Brakes

  • 345 x 32 mm (F) and 328 x 20 mm (R) floating rotors
  • BMW Motorsports 4-pot (F) and mono-pot (R) calipers


Auction description (08/04/2016):

This 850i was purchased new in 1991 by Donald Rojas of Austin Texas. In April of 1994 Donald sent the car to Dinan Engineering in Mountain View California for a Stage 3 factory performance conversion. At the time of the conversion, the 850 mileage was 36,248 miles. This is one of only seven 850i stage 3 conversions performed by Dinan. The conversion consisted of creating a CSI base, increasing the engine displacement to 5.6 liters, same as the later 850 CSI, installing twin turbochargers and intercoolers, New computer chips for the engine and transmission, free flow exhaust system, high flow intake manifolds, transmission cooler, high stall torque converter, improved brake and suspension systems, and other improvements all of which are listed in one of the photos. The engine was then dynamometer tested showing 607 horsepower at 5,500 RPM and 666 foot pounds of torque at 4,500 RPM (graph in photo).

The 850 was sold to Jay Cooper from Edmond Oklahoma in 2005 and then purchased by me in 2006. At approximately 65,000 miles, an engine ticking noise was noted that sounded like a valve train noise, after over a decade since the conversion this seemed like a good time to refresh everything under the hood from the big stuff to hoses, belts, etc. The engine was sent to Dinan Engineering for an engine rebuild, overkill but since the engine was out it seemed like a good idea.

Golz in Deerfield Illinois rebuilt the heads including new lifters and other valve train components before assembling the heads to the new engine block assembly from Dinan. Since the engine was out of the vehicle and the 850 had accumulated 65,000 miles, it was decided to replace all the other mechanical components such as the water pump, fan clutch and blades, all belts and hoses, new improved turbochargers and waste gate valves, new DK motors, steering box, and other components as listed in the photo.

The 850 has been well cared for. The body, paint and upholstery are totally original. It is absolutely free of rust and in excellent mechanical condition. I have had it insured as a classic car by Hagerty Insurance and it has only been driven to car shows and other special occasions the past several years.

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