ANDIAL ROAD AND RACING
SPECIAL ENGINE PROJECT – 3.7L FROM 3.2L CARRERA (1984-1989)

This conversion is based on the 3.8L RSR technology. The RSR has a 76.4mm stroke crankshaft and 102.0mm bore cylinders resulting in a displacement of exactly 3,743.8mm. The cylinder base sealing is done by the use of an O-ring imbedded in the crankcase bore. No copper gasket is used between cylinder and crankcase.

The 3.7L engine conversion for the 3.2L differs notably from the 3.8 RSR as follows:

• The crank has a 74.4mm stroke instead of 76.4mm
• The housing studs are closer spaced
• The cylinder heads to cylinders use a different mating pattern

For cost reasons, ANDIAL decided to utilize the 74.4mm crankshaft. We are using the original RSR 102.0mm pistons with reduced compression. The shorter 74.4 mm stroke puts the piston 1.0mm below the desired T.D.C. (i.e. 76.4 – 74.4 = 2.0mm total difference or 1.0 mm per side). To compensate for this difference ANDIAL had Carrillo make an RSR connecting rod that is 1.0mm longer, placing the piston in the correct position.

A special cylinder was manufactured by Mahle. It has the correct cylinder stud spacing, the proper match for the cylinder heads and is 4.0 mm longer than standard. The cylinder is longer because the case is machined down 4.0mm to provide a solid footing for the larger cylinders. The case is also bored out to 107.0mm to accept the cylinders and an O-ring grove installed. ANDIAL provides this case machining service, or as an alternative, a good machine shop can do the modifications following our instructions.

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