M20B28 Engine Build

Reader Comments

1. What is the all sizes of the spacer at the front of the crank for the oil seal to sit on? For m20 2.8

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   1. Hi Roberts, I’ve added the crank spacer diagram to the gallery above (last image). It is sources from e30zone.net. I used to as the base but sorted out the final details when I turned the piece on the lathe.

      Thanks, Patrick 🙂

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      1. Hi! Are you using stock piston on your M20B28 ??

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         1. Hi – I used the stock M20B25 pistons from a 1988 model. They are short skirt type. If you use early model pistons the the skirts get in the way of the conrods.

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            1. on stock 325i ECU/DME ?

            2. Stock ECU, chip tuned for 2.8 capacity 🙂

2. Patrick I’m lost in details,but can you tell me one thing? The engine block you used in your m20b28 is it from a 2 liter M20B20? Or a bigger 2.5 liter m20b25? I find amazing that a m52b28 crankshaft would fit an M20B20 or b25 block. I am very curious because I would love to increase the cc in my M20B20 wich currently “lives” in a 1990 E34 520i. Thank you!

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   1. Hi, the block is from an M20B25, as are the pistons. The conrods are from the M20B20 – they are a little bit shorter than the M20B25 ones. All that’s needed to make M52B28 (non-VANOS) crank fit is a spacer for the front of it. You need to check piston skirt clearance too – some of the earlier M20B25 pistons have longer skirts.

      I believe it is possible to use the crank from an M54B30 but that’s needs custom conrods and pistons. Each BMW 6 cylinder is a futher development of the previous generation so there tends to be some compatibility between them.

      Thanks Patrick

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   2. There’s a more concise page about the engine build here:

      http://www.msportster.co.uk/question/m20b28-build-in-full/

      I can also recommend this really good article on e30zone:

      https://www.e30zone.net/e30wiki/index.php/Building_a_2.8

      Thanks Patrick

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