E89 DIY - Inlets install on 35i


May 30, 2019
35i e89

I thought a guide on how to install inlets on the E89 Z4 would be helpful since there wasn't a lot of information online about it on our cars. You can find plenty of guides for the 335i but the Z4 is a bit different. Because we're fortunate enough to have a lot more space under the hood a lot of the steps needed for the 335i install are not needed in our case. Also, you may want to attempt this yourself but because of the 335i procedure it might be discouraging at first but I'm going to prove the contrary below.

I'd like to apologise for the lack of visual content, I should've took pictures but I was rushing as I borrowed someone's lift in a garage. Instead, I'll try to use pictures from realoem.

1. Remove your DCI / airbox
2. Remove the FAN connector and the screw holding the FAN at the top

3. Remove the shield from underneath the car
4. Cars with DCT/Auto gearboxes will have this heat exchanger holding the FAN at the bottom in 1 torx screw - please remove it

5. You should be able to remove the FAN upwards now
6. After the FAN is out of the way, remove the screws holding in the front inlet

7. There will be some hoses clipped in - you should be able to use common sense and realise what needs to be popped out of place
8. The inlet should come free now - wiggle it, be gentle, there are lots of coolant hoses around there that may be old
9. Take a second to admire your turbo

10. After you're done looking at the thing that makes you go fast, take the silicone inlet and put some grease on the part that is going to rub against the coolant hoses so you make your life easier (make sure there's no grease on the inside of the inlet otherwise it might slip off the turbo)
11. There is a small metal edge very close to the turbo snout so take that into consideration when positioning your clamp
12. Fix the inlet in place and remove the screws holding the coolant reservoir
13. Move the coolant reservoir towards the radiator, disconnecting the sensor will greatly increase the range of motion (ideally have someone to hold it for you)
14. Tighten it in place (i found it easier using a long ratchet extension and holding the clamp with my right hand so the clamp is not pushed downwards by the ratchet)
15. Based on your silicone inlet brand you may have to use cable ties in order to avoid the pullies eating the inlet, I used one on the fan housing in order to keep it away from them
16. This should be it for the front one

1. Remove the DV and PCV connector
2. Remove the screws holding in the heat shield at the top
3. Remove the screws and bracket holding in the rear inlet

4. The rear inlet should be loose now and ready to be removed - wiggle it it should come out quite easily
5. Prepare your rear silicone inlet with some grease (i used grease all the way up to the 90 degree elbow that goes on the turbo)
6. Put the clamp on and try to keep it grease free
7. Slide the inlet on (make sure not to catch the wastegate vacuum line and wonder why it's not going on for 5 minutes)
8. Use a long ratchet or flathead screwdriver and secure that bastard in
9. Put everything back together and job done

As you may have noticed, there is no mention of downpipes/steering rack removal because it's not needed. The rear of the engine is very accessible so there's no reason why you should go through any of that. Most of the work is done at the top, you only need to go under the car to remove the heat exchanger screw holding in the fan. Also, no cutting is needed either, both inlets can be removed easily without cutting anything.

Hope this guide will benefit people that are looking at having inlets installed on a z4. This is my way of giving back to the community for the plethora of information available on the N54 platform. Any questions please ask.
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Nov 24, 2017
Indiana, USA
Z4 35is, 535xi, X5 35i
Also, because the rear pipe has so much room to move around, it is very easy to pop it off the turbo Inlet just working in the engine bay removing the air filter, etc.

I zip tied it to the rear of the valve cover where the original mounting point is and that took care of the problem.


Lieutenant General
Staff member
Aug 11, 2017
E89 Z4 35i, F10 535d
Let me add a few things. BTW I love the fact that you posted this. Keep posting - I agree not much getting posted on the Z4. The general silicone inlet solution is amateur hour on the N54 but a lot of us run it. I was appalled by the front inlet dangling between the motor and fan. Turns out there is an M5 (if I recall) boss that is unused on the front of the motor. Perfect for an Adel clamp to hold the inlet snugly and keep it from flapping into stuff.


Second, rounding the alternator, more flapatosis. We made a bracket that also holds everything firmly at the ends. You can probably fashion something homebrew style - consider these photos for inspiration.