Posted by Mike W. on April 30, 2007 at 20:45:12 from 207.200.116.196
In Reply to: '85 635Csi engine into an '80 528i posted by Rick in Colorado on April 30, 2007 at 19:30:36:
It depends on if you want to go Motronic engine management. If you do, you need the motronic bellhousing, a motronic flywheel, the reference sensors that plug into the bellhousing along with the complete motronic wiring harness and ECU. Motronic is a better system, but it isn't magic. You can get a smoother engine, smoother torque curve with perhaps slighly more peak power, but not much, and slighly better mileage.
If you retain the original L-jet with lambda, power will peak around 5K instead of 5400, and have much more torque. To stay with L-jet you need to get an adapter for the nose of the cam and use your existing upper timing cover and distributor.
Expect to pay about $150 for a bellhousing and flywheel, or $40 for the adapter nut. Prices aproximate of course, YMMV.
Mike