Engine Position I 
 

The cars Alpina built before 7/87 were the inspiration for Engine Position I. In this position the engine sits well forward in the engine compartment. Due to limited space, the water pump connecting pipe is cut off and the fan is not used. To achieve a proper rate of cooling, an electric fan is installed in front of the radiator.  This is a popular modification to the e30 even with the M20 engine, and is used in many cars to keep the engine temperature within reason. No modifications to the firewall or the floorboards are required in this position. In fact, several centimeters gap remains between the rear of the engine and the firewall. However a special radiator (Alpina) is required. The radiator must fit within the front mask, as there is no room in front of the engine within the engine compartment.  As an additional benefit to this position, the clutch can be changed without removing the engine, as access can be gained from underneath. This engine position was used in all of Alpina's models up until 9/87, thus the aluminum engine mount brackets from these cars can be used. This position will, however drastically alter the handling characteristics of the e30, as the weight distribution is shifted forward to a high degree. Also, obtaining original Alpina parts (engine mount brackets and radiator) will prove extremely costly. Furthermore in this position the engine sits quite high, and Alpina used a special intake to accommodate the height.

Engine Position II 
It is easier and greatly beneficial to the handling to install the engine further back. This way the excess weight of the M30 over the M20 (about 60Kg or about 132 Lbs) weighs less heavily on the front axle.  This position results in a less "top heavy" handling characteristic.

No modifications to the firewall are needed in this position, either.  The water pump connecting pipe must still be sawed off, but no special radiators are needed.  The e28 535i radiator is a direct fit.

Should the clutch need to be replaced, the engine and transmission will need to be raised and lifted forward for access.  This is not a significant disadvantage to mounting the engine in this position, as this should occur very rarely.
 

	Engine Position II.  Here you can see that there is enough room for the e28 535i radiator.  Also the firewall remains unaltered.  Depending on which exhaust system is used, a modification to the floorboards under the front passenger seat may be needed, to prevent bending the down pipe.
	Alpina used this position for its cars starting after 9/87.  The newer steel Alpina engine mounts hold the engine in this position, and are thus suitable choices for the 335i.   Alpina B6 3.5 beginning 9/87 (Engine Position II)
	Here the e28 535i radiator is installed.  The shortened connecting pipe of Engine Position I remains.  With this setup the engine has around 2-3 centimeters of clearance to the radiator.

Engine Position III
In this position the engine is placed still further back. Nearer to a position that would not upset the handling of the car.  The firewall must be altered in the area around the cylinder head. This modification is, however relatively easy to do.  About 4-6 cm must to cleared out of the firewall to provide room for the engine to be mounted in this position.  This does, however leave room for a radiator and fan in front of the engine, and still in the engine bay, unlike the other engine positions. 
 

	Combining this position with the e28 535i radiator leaves room for the fan clutch.  This is desirable to eliminate future cooling issues, or problems that may result from the use of an electric fan.   B7 Motor in an E30
	Engine Position III: Plenty of room for the radiator and fan.  Note that modifications to the firewall are necessary.
	Harge's H35 is a great example of Engine Position III.  Hartge relocated the battery, and the windshield washer fluid reservoir to the trunk.  They claimed they maintained the factory weight distribution of the 325i.
	Engine in position III in an e30 cabrio.  This left plenty of room for the e28 535i radiator and a clutch fan.  Modifications to the firewall were, however needed.  This position also leaves room for the use of narrow oil coolers.  The handling characteristics of this setup hardly differ from those of the factory 325i.

Questions, Comments?