How To M50 Manifold Swap an M52 Engine | M50B25 Intake Conversion Guide for M52B28 Swapped E30 | 053

How To M50 Manifold Swap an M52 Engine | M50B25 Intake Conversion Guide for M52B28 Swapped E30 | 053

Here are links to things I used in this video:
Creation Motorsport M50 Inlet Swap Kit: https://ebay.us/qGpx5S
Correct Long E34 Throttle Cable for E30 Swaps: https://ebay.us/UJ1xq8
Normal M50 Inlet Swap Kit (No Chopping): https://ebay.us/TV4O6Y
An M50 2.5 Intake Manifold: https://ebay.us/PL11lT or https://ebay.us/K3uxPI
M50B25 Intake Manifold Gasket Set: https://ebay.us/5eH7xI
Brass Fuel Line Adapters: https://ebay.us/YyJBbB
Full Replacement PCV Valve Kit: https://ebay.us/gODNrS

In this video, I take on the challenge of converting my M52B28 motor to use an M50B25 intake manifold.

In my case, this just so happens to be in my M52 swapped E30, but this guide still applies to you if you are trying to fit an M50 intake to an E36 328i or an E39 528i, or E38 728i.

The intake manifold you want to swap your standard M52 one for is most commonly found on an M50-engined BMW E34 525i.

Let's start with the why, it seems counterintuitive to want to fit a 2.5L engine's intake manifold to your larger 2.8L motor. However, the runners on the M50 manifold are approx 60% larger than the M52 manifold so flow more air.

Why did BMW not just use the m50B25 manifold on the 328i M52 in the first place? Good question, likely down to things like emissions and fuel economy, plus the type of car the M52B28 was mostly fitted to.

Bear in mind, those who chose to purchase a 328i, 528i or 728i were not trying to buy the flagship sports model of BMW, they'd opted away from a serious M car to something more daily driver-friendly, but still with grunt.

Using the narrower runners on the 2.8L 6-pot changes the characteristics, with increased air velocity at lower RPMs, the M52 engine produced more low-end torque which makes wafting around feel more effortless. Some of this low-end torque will be lost by fitting the M50 manifold, especially without a good remap to optimise it, but in its place people report peak power gains of beyond 20bhp which is remarkable for a bolt-on mod to a naturally aspirated engine.

As with everything, there are pros and cons, and that makes fitting the M50 inlet a fairly controversial decision. Some love it, some hate it. But as I am a lover of revving an engine out to extract its performance, I think it will suit me perfectly.

So let's get on with the how. Sadly one cannot simply swap an M50 manifold onto an M52. Unfortunately, there's a bit more to it than that. I have been very lucky in being able to purchase an M50 manifold that was already modified to have the port plate from an M52.

This was done by blocking of the single hose connector and chopping a window into it, glueing on an aftermarket plate that allows the M52's plate to screw on. This means normal M52 ports and bracketry for things like PCV, ICV and vacuum lines on your M50 intake.

This method seems old-fashioned now as it involves chopping a very expensive part, thus these plate kits seem to be NLA, so I can't find one to link. Luckily the alternative way is still popular, it involves getting a hose that goes into a T-piece to allow for both ICV and PCV fitment. I've linked it above.

I opted to buy a completely new PCV, which was actually quite cheap to do, linked. You will also want to take a minute to make sure your ICV isn't gummed up, if you shake it in a rotating motion it should clack back and forth. Be aware that the ICV pipe is a common pain point as prone to splitting. I glued mine successfully.

Once that's been solved, you still have the issue with the throttle body. The M50 and M52 throttle bodies are very similar in design, and have the same bore so nothing to gain by swapping.

As you're more likely to use your original throttle M52 throttle body you will encounter an issue with the throttle body gasket. The M50 manifold has the seal mounted directly on it, but the M52 mani does not - it's on the body itself.

Unfortunately, two seals don't make a seal in this case, so you will need a plate linked in the Creation Motorsport kit which effectively sandwiches between to give a sealing surface for both gaskets.

In my case, with my car being an M52 swapped E30, I have to also switch to an E34 Bowden cable to make it work, linked too. I also used brass adapters to connect the chopped fuel rail lines to the E30's stock fuel lines.

Sadly, the M52 fuel rail will not be a direct fit to an M50 intake manifold, so again you need the linked adapters to do this, along with a minor fuel rail bracket chop.

For more helpful how-to guides and restorations: https://www.spannerrash.com/

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#bmwe30 #e30build #m52 #m50 #m50manifold