E34 S52 Intake, Exhaust & Fuel

I used the stock E34 525i intake system, including the intake elbow and intake box - although I used a rotary tool to widen and radius the inside of the intake box to facilitate the increased air flow from the larger engine



I used the M50 intake manifold with fuel rail although there will be some complication when it comes to retrofitting the S52 CCV system to the M50 manifold. The most proper way to do this is to use an M50 manifold adapter kit and weld a return bung onto the E34 dipstick tube for the CCV return/drain hose and maintain the S52 CCV system. That is what I eventually did, as pictured below before the dipstick was painted



Alternately, you can rig up the M50 system without a CCV to be made to work but this always looks a little janky and there are other compromises that you have to make to do it like this. As you can see in the below image, I did experiment with doing it this way but ultimately decided it was worth the extra effort to do things properly



The M50 manifold requires either using an M50 throttle body or an adapter plate for the S52 throttle body. Some people double up on the S52 throttle body gaskets and install it like that, but I am not convinced this creates a secure gasket connection as you are sealing a pliable rubber gasket against a pliable rubber gasket. I also chose to maintain the stock M50 throttle body cooler and it's associated thermostat. It is very easy to bypass this system, but my goal here was factory functionality and appearance, so I chose to maintain it


As far as exhaust goes, stock E34 headers will bolt to an S52 and would appear to be an upgrade over stock S52 units as M50 headers are a larger diameter. We swapped the stock M50 headers onto the S52 and they bolted to the stock exhaust no problem



For the fuel system, I swapped the E34 fuel pump to one from an S52 powered car, while maintaining the stock E34 housing. No further modifications were necessary because M50 and S52 receive fuel in the same places so even fuel supply lines are the same Note: the S52 era cars use a fuel regulator valve near the fuel filter, whereas E34 M50's used a fuel regulator valve mounted on the intake manifold. Because I swapped the M50 intake manifold onto the S52, the fuel regulator valve is not an issue, as it stays in the original location. As such, if you want to maintain the SS2 intake manifold you will need to install a fuel regulator valve near the filter, like the E36 S52 setup



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