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M10 options


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Hey there! I have some questions about the compatibility of the M10 from other models into the 2002.

I may have the opportunity to get the M10 out of an 84 e30. First, will the 2002 intake manifold and carb fit onto it? Will it bolt up to the stock 2002 trannny?

Or, i can pull the engine out of a e21. Same questions. Will the manifolds bolt up, and will it bolt up to the tranny?

And finally, will the bottom end out of an e21 bolt up to a 2002 "e12" head?

Thanks for all your help, it's greatly appreciated!


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Yes all the M-10's are interchangeable. There are a few differences. The e30 (and some e21?) have the distributer spin the other way. That means the housing at the back of the head, distributer and the cam are also different. The later e21 and e30 M10's are also 1.8 liter and not a 2.0 like the 2002 and early e21. The e30 M10 has the lowest compression stock but has the highest stock flowing head (referenced form somewhere). I also think the e30 M10 is the smoothest running of the bunch. And the hp is not that much less for it to be a factor as far as stock motors go. Of course, if your starting fresh I don't see much reason going to a 1.8 over a 2.0. Maybe for a turbo setup.....

Also keep in mind that higher compression pistons are not interchangeable with all the heads.


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same bellhousing pattern, intake/exhaust manifold flanges, etc, but there are significant detail variations over the 20 year production span from the mid 60's to mid 80's.

Not all crank / rod / piston combinations are compatible with all blocks due to bore & stroke variations; combustion chamber sizes and shapes changed over time so some pistons won't work with some heads; some fuel injection systems had injectors in the intake manifold runners, some in the heads, and later (E21/E30) injected engines didn't have the mounting boss for a mechanical fuel pump machined. Camshaft rotation was reversed on later motors, and cast-in accessory mounting bosses are also different between early and late motors.

There's been a LOT of discussion on this topic on the board - you may have to plow thorugh a lot of different threads, but you should be able to mine a lot of info from the archives............

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