N52 Swap Discussion

[hoveringuy]

Looks good, is it just the angle of the photo or is the engine very close to the radiator?

I think the engine is identical in distance to the radiator as my M54 was, the issue with the N52 is that the coolant bypass hose runs in front of the engine and it gets within 8mm of the radiator. To the point where I'm not sure if I could run anything thicker than the OEM 33mm core in an all-aluminum radiator, for instance.

Meanwhile, at the back of the engine there's miles of clearance...

The positioning was predicated on the shifter being centered, naturally, and my shifter is maybe 5mm forward of the middle so there's future opportunity for the motor to slide back just a hair, probably 1cm.

It looks much better from the bottom, where I have 2" clearance between the damper and the radiator core.

[Caperix]

Looks good, is it just the angle of the photo or is the engine very close to the radiator?

[hubcapboy]

It's from all the lightness we added

[nando]

Nice! Also, does it have a lift kit? :p

[hubcapboy]

Hey look what showed up at my house the other day tootin' it's own horn:

[hoveringuy]

Throttle pedal, done.

I'm using the Z4 manual pedal which is considerably more svelte than an E90 pedal or anything else. The usual route is to use an E46 pedal and make a bracket and some epoxy, but I think this worked great.

The pedal (P/N 35426853176) is meant to be mounted with an allen head bolt through the baseplate, so I welded an M6 nut in front of the e30 bracket for it.

The rear has a cavity where a catch plate grabs the top of the pedal and secures it from lateral movement as well as rocking forward. Conveniently, the e30 bolt hole sits exactly in that pocket so it was a quick matter to fabricate a plate. It slides down onto the plate and is then bolted at the bottom.

Rock solid!






Comparison of the two pedal styles. The Z4 style (left) is over 1/2 lbs lighter and the plunger is more robust. BOTH of them have the recess in the back for the catch tab. They work the same, but the plug is different between them.

[hoveringuy]

Now that I have it running, I'll switch my E90 injector harness for an X3 one. E90 is incredibly short and won't reach the glovebox

X3 could reach the passenger seat. Or the backseat

E90 top, X3 bottom.

The X3 uses a completely different style of alternator plug, the Valvetronic relay isn't incorporated and there are some other slight differences, but nothing major.

[hubcapboy]

This is outstanding work.

[hoveringuy]

Finally, here's what my exhaust looks like. 2" secondaries into a Burns merge, 2" to 2.75". Why 2.75"? Because 2.5" is too small and 3" is too big....

[hoveringuy]

There are two versions of the thermostat. The X5 and most others. They both work fine, but the X5 one (left) has a 90 in the outlet that results in more direct and cleaner hose routing.



The upper hose is presently a 45 degree fitting and an E30 upper hose. Not difficult.
Missing from this picture are two things 1) the e30 cluster temp sender and 2) a 3/4 nipple on the hose that feeds the heater core.

My plan is to use an M54 straight fitting with the temp sender taken off the lower radiator hose of an M54. That's where the e30 temp sender will live in place of the 45 fitting.

There are off-the-shelf radiator hose adapters that that will give me the 3/4 hose fitting, but I plan to fabricate a stainless 90 at the rad inlet that will allow a tighter 90 required to have the straight fitting on the engine, and that will have the 3/4 hose drop straight down next to the radiator end cap.



Purging the cooling system. You just let the electric coolant pump run for a few minutes and you're done. Neat-O!

[hoveringuy]

The lower radiator hose ended up being a Gates 21887 hose matched with the 90 degree fitting that normally connects to the E90 radiator, except it now connects to the thermostat. The indexing tabs on the thermostat need to be removed so that the 90 can rotate.

There are two versions of the 90; some have the fitting for the radiator outlet temperature sensor, which is used by the DME to control the aux fan. I use the e30 dual-temperature switch in the stock radiator, so no temp sensor here.

What does the Gates 21887 normally fit? It's the lower radiator hose for an E30 with M20. A sign from the Gods! *Update* The M20 upper radiator hose, Gates 21886, actually has a tighter 90 and can be cut to fit. Both work, I think the 21886 works better.




The sharp-eyed may have seen the cross-under tube in the post above and thought I grabbed some conduit I had laying around to fabricate my cooling system. Nothing could be further from the truth, it wasn't laying around- I had to go out and buy it.
it's a prototype to see how it works, the final one will be some kind of bent 7/8 stainless pipe. It replaces the plastic piece found on E90's that won't fit the E30. It's meant to connect both the cooling reservoir* and heater core return to the thermostat.
Works just fine so far. Routing is tidy. Next...



* I'm running the stock e30 reservoir, but there's no reason that it couldn't be on the passenger side. The cross-over would still be needed for heater core return.

[hoveringuy]

My task an purpose this week has been to complete the cooling system and get enough of the exhaust done so that I could let the car idle.

The first challenge was the hose from the radiator to the thermostat inlet. It's tight, and the hose was initially riding on the radiator with a kink in the bend.

Fortunately, the thermostat is bolted to the water pump and can easily be moved back so I did that. An aluminum adapter plate, the holes are 25mm on-center and I moved them at a 30degree angle for 30mm. The math inclined will calculate that it results in an extra 15mm of clearance.

Lots of clearance everywhere now. Sorted.

[wazzu70]

Great update! All these N52 projects are inspiring and its nice to see the solutions available. With Nandos ECU coding it makes it really easy to do this swap without a standalone which is awesome.

[hoveringuy]

One other thing that has been absolutely priceless is the OBD2 port.

The Z4 uses K-line bus communications and the E90 that my harness came from doesn't, so I had one missing wire in the harness to make it work. The #2 pin next to the wake-up signal on #1 needed to be added, that's the K-line signal. Once that was done there were only 3 wires to my OBD2 port: K-line, power and ground.

It's been incredibly useful, because when the engine doesn't start, and you have 6 codes, one for each individual injector being open-circuit, it's a great tip-off that you should probably plug the injector harness in....

I'm working on getting INPA so I can go deeper.

[hoveringuy]

The driveshaft isn't actually fabricated yet, this is a dramatic re-enactment to show how it will look. I cut it to the correct length and dropped it at Drivelines NW hoping they could just weld my yoke onto the e30 shaft but they said it was non-serviceable, I'm having a completely new shaft fabricated. I believe an M3 automatic front section would have fit, however.

These photos also show the difference in how the GS6-17 transmission found in the 328i fits differently than the longer GS6-37. I have the exact same mounting tabs as a G260 and was able to re-use all of my stock mounting hardware. Nice!

X3 booster has miles of room.

I did get the motor to start!

Many thanks to Nando for coding the ECU and providing technical assistance. My MSV70 is coded as a 2007 Z4.
It took exactly 3 wires on the ECU external to the motor to get it to start. Battery, Ground, and the wake-up (IGN) wire. That's it!
I jumpered the fuel pump on and manually energized the starter solenoid. It starts and runs. (loudly, as my neighbor pointed-out..).
After I got it running I wired-in my EKP fuel relay and had an issue with the fuel pump coming on with IGN and staying on. Nando pointed-out that the EKP fail-safe when it doesn't have communications with the ECU is that the pump stays on.
So, even though I had an EKP and the connectors from an X3 which was clearly labeled as a "CAN 11h" protocol unit, there's a difference in how the CAN lines are terminated in the X3 versus the Z4. Remember the ECU thinks it's in a Z4....?
The X3 EKP plugs are missing the jumper loop between pins 8 and 15 and once I added that loop it works great. Pictured is @hubcapboy's Z4 EKP plug.

If I apply wake-up power to the EKP without power to the ECU, the pump will run and stay on. As soon as I apply wake-up power to the ECU the pump shuts off until the ECU senses engine rotation and then the pump comes on again. Sweet.

To do: I need to finish fabbing the exhaust now that I can work with the motor in the chassis and figure-out the cooling system.


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