Category Archives: Automotive

M10 to M20 Engine Swap – ’77 BMW E21

The time is finally here. After helping Ed through research and general work its time to get the M20 into the E21.

Whist it might look like we’re stood around most of the time, there is a lot of ‘Man Maths’ going on here. Trying to get this 6cylinder engine into an engine bay that it was never designed to go into.

Lucky for us, because an M20 variant was placed in the E21 chassis from the factory we can use the original engine mounting points. Well I say this but this now has a series 2 subframe on it and brand new E30 325i OEM engine mounts.

It was a tight fit, especially over the front slam panel. There are a couple of mounting points on the back of the engine that kept snagging on brake lines and the firewall as well. We all had to keep our eyes pealed for any snagging.

When the engine was ‘in’ the bay, we then had to get it lined up onto the engine mounts. Unfortunately because of how we mounted it the engine crane it was sitting to far to one side. So, the trolley jacks came out to jack the engine on one side pivoting the engine mount inwards so it could be bolted it.

It’s now in and settled, nearly ready to be started now……

M20 Engine Stripdown

As part of my ‘testing’ for timelapse footage I brought my GoPro over to my friend Ed’s to get some footage of us stripping down and cleaning the BMW M20 ready to go into his E21. The M20 is replacing the M10 that has a tiny¬†40k on it from factory. The E21 in question was built in ’77 so the mileage on this engine and chassis is nothing. The M10 block is a 4 cylinder, 1.8(carb) with 90bhp, whereas the M20 is a 6 cylinder, 2.5i with 170bhp. This E21 is going to fly!

The day was a real test for the GoPro as I still had the single original battery, unfortunately it didn’t last long enough :( I shot this a few months ago so I can’t honestly remember the settings I was shooting at.