M20 "Baby Six"

325i/e, 528, 525i ≥ '91 - 6 Cyl SOHC* Engines
*Single Overhead Cam
Engine SeriesHorsepowerPrice
Core Deposit
E9 - MM 3200 Rally Engine270 HP$16,000$1,500
For ix's, Customer's Core & Additional Charge$300
Options: for the 3200 Rally Engine
MM 12 lb Billet 240 mm Steel Flywheel & High Torque Clutch Assembly with 9 strapping bands$1,500$300
M20 Pulse Chamber Intake Manifold$1,750Manifold Deposit $250
E10 - MM 2800 Boosted Engine14 lbs (1 bar) 500 HP$18,000$1,500

2900 Sport Engine   This build is a great replacement upgrade engine for a stock engine, a true value and a perfect daily driver that provides a sizeable performance increase over a stock engine. In a 325is, the 2900 will run the quarter mile in 14 seconds at about 100 mph and still have the life span of a stock engine, some 200,000 miles.
3000 Sport Rally Engine   A rugged engine for the BMW enthusiast who wants to use a street car in Autocrossing and Driver’s Schools events. This is achieved by combining our deep valve pocket sport pistons with our Rally Engine “H” Beam rods and 84mm stroke crank (86 option is available).
3200 Sport Engine   A “torque lovers” engine built much like our 2900 Sport Engine but larger. The extra displacement results from employing a longer 89.6mm stroke crank and lighter 135mm I Beam rods.
3200 Rally Engine   Our “King Kong” M20 engine for Autocrossing and Driver’s Schools. Will do the quarter mile 13.5 seconds in 105 mph! ‘Nough said!

ALL our Normally Aspirated Sport, Sport/Rally & Rally Engines include the following mechanical upgrades:

  1. Machined and hand ported head with 16.5% flow increase.
  2. Surface Turbulence treatment to the Head reduces detonation, virtually eliminates head cracking, results in greater fuel economy and lower emissions.
  3. Sport Camshaft that offers good idle and driveability.
  4. Modified Head Gasket to improve water flow to the back side of the 4th and 5th combustion chambers – to prevent head cracking.
  5. Stronger 10mm socket Head Bolts for increased clamping load on the head gasket.
  6. New Rocker Arms, 30% stronger than factory. They can handle 525 lb.s whereas the stock rocker arms breaks at about 400 lbs or less.
  7. Lightweight “Bee Hive” Valve Springs & Retainers to reduce Valve Train load.
  8. Manganese Bronze Valve Guides for tighter valve stem – to guide clearance and extended guide life.
  9. All Sport and Sport/Rally Engines have deep valve pockets to prevent the valves from contacting the piston in case of a timing belt failure. Note: To reduce flame travel distance from the spark plug to the piston top, this modification is not performed on our Rally Engine pistons. Routine Timing Belt changes should be made. We recommend Continental Belts changed every 45,000 miles.
  10. Moly Top rings and 3 piece Oil Rings for good oil control & long life.
  11. Rally & Sport/Rally Engines use Coated Tri-Metal Rod Bearings on standard rod journals to prevent rod bearing failure and for greater load carrying capacity.
  12. All our M20 engines have 360° oiling groove main bearings to prevent oil starvation to the rod bearings at high RPMs.
  13. Ported and Blue Printed Oil Pump. Ported at the discharge port and enlarged at the oil feed galley on the exit side of the oil pump for greater oil flow.
  14. Horizontal Oil Baffle in the Oil Pan, to prevent oil starvation under hard cornering.
  15. Optional Windage Tray/Scrapper Bar, Horizontal Baffle and Swing Gate to prevent oil starvation to the oil pump pick-up. These additional modifications, priced at $750, are strongly recommended for track event participants.
2900 Turbo Engine   Specifically “beefed-up” to take boost! Everything from the top of the piston to the rod bearings has been re-engineered and designed with boost in mind. We use a tough 84mm stroke chrome moly forged steel crank (86mm option).
3100 Turbo Engine   The “boost junkie’s” maximum fix built around the 89.6mm stroke chrome moly forged steel crank.

Our Forced Induction Engines include all the modifications listed above plus these mechanical upgrades:

  1.  Our special composite Head Gasket is used on engines running up to 15 lbs. Boost. For engines exceeding 15 lbs. boost, we use a Multi-Layered Head Gasket.
  2.  Our 85mm, 8.2:1, Forged Alusil, Forced Induction Pistons are designed specifically for boost and have the following features:
    1. The piston crown is protected by a ceramic coated heat barrier that can take 1350° F continuously. Also, the crown is .080” or 2mm thicker than our normally aspirated pistons – for greater boost load.
    2. The top ring is moved down on the piston for greater temperature and load protection.
    3. Higher radial tension 4mm wide oil ring for better oil control.
    4. Ventilated skirt design to reduce piston expansion.
    5. Our Turbo Pistons come with a dished top design. Corner valve pockets are not included since the pocket edge is the first area to melt under excessive high temperature.
    6. For those wanting to run more than 12 lbs. boost, we recommend welding the top of the camshaft valley onto the intake side of the head at the number 4, 5 and 6 cam journals. Price for this modification is $750.
  3. “H” Beam Rods are used for higher load carrying capacity. The big end of these rods has four squirter grooves for shooting oil towards the bottom side of the piston to keep it cooled off and to lubricated the cylinder wall.
  4.   Heavy duty 105 gram wrist pins. Our normally aspirated piston uses 80 gram wrist pins.
  5.  Our High Volume Oil Pump with 25% larger gears than used in our normally aspirated engines. This allows for greater oil supply feeding to the Turbo Charger.