N52 Swap Discussion

[hubcapboy]

Real time update: Turner already designed a kit that breaks off the intake air temp sensor and uses a $15 sensor to be installed in the airbox... I can't think of a reason not to just install and connect to this sensor. *Particularly* since it can go anywhere, rather than in a special intake tube with a socket designed for the MAF!

[hubcapboy]

This ECU fan control pleases me. I expect that this is exactly what I'm going to be doing, with an additional override after the fan control box that puts my fan on high speed when my AC compressor clicks on. I won't have any feedback issues with an override switch... the thermostat will just behave as designed.

I'm currently extending and appending a Z4 wiring harness to suit the chassis (documentation to follow) and I want to confirm what we'd previously discussed related to the MAF/IAT sensor, because I have a pin number mismatch between the connectors on the X3 and Z4 harnesses I'm combining. Here's the BMW diagram for several of the N52 engines:





Pin 4 on the connector is always sensor ground (M_HFM) and Pin 5 on the connector is always the Intake Air Temperature Signal (A_TANS). These always connect to pins 27 and 28 respectively on DME Sub-connector X60005.

Pin 1 on the connector is always the MAF signal (A_HFM), but the DME pin for that signal changes between models. *I believe* this becomes moot, because Nando's tunes specifically do not use this sensor. Looking at the last diagram, "depending on version" some e90's after 2007 have a IAT sensor that doesn't include any MAF function or wiring. Which versions? Here's one example of a part number:

13627547822

Intake air temperature sensor

From:09/01/2005To:-Weight:0.016 kgPrice:Part 13627547822 was found on the following vehicles:

• 3' E90   (02/2004 — 08/2008)
• 3' E90 LCI   (07/2007 — 12/2011)
• 3' E91   (03/2004 — 04/2008)
• 3' E91 LCI   (05/2008 — 02/2012)
• 3' E92   (05/2005 — 02/2010)
• 3' E92 LCI   (09/2009 — 08/2012)
• 3' E93   (10/2005 — 02/2010)
• 3' E93 LCI   (09/2009 — 09/2013)
• 5' E60   (07/2004 — 02/2007)
• 5' E60 LCI   (11/2005 — 12/2009)
• 5' E61   (07/2004 — 02/2007)
• 5' E61 LCI   (11/2005 — 03/2010)
• 6' E63   (02/2004 — 07/2007)
• 6' E63 LCI   (05/2006 — 07/2010)
• 6' E64   (03/2004 — 07/2007)
• 6' E64 LCI   (05/2006 — 07/2010)

These are all European n52 models, but curiously not the European Z4... which kept the full sensor!

Rather than having these extra signals, grounds and power signals floating around in my harness, I'm going to pull everything but the two wires for the IAT out. Even if I left them connected, I have a 50/50 shot of knowing which pin we would send the MAF signal to based on the info above.

I don't know if power or additional grounding is required for the sensor I have to detect temperature, but I think it's unlikely. If I don't get an intake temp reading when this goes together, I'll track down on of the 13627547822 sensors. Here's the difference:

[hoveringuy]

So from my post above you've gathered that the thermostatic cooling fan and the MSV70 fight each other, and the MSV70 wins. It just says "fuck you" and reduces the coolant flow leaving the aux fan running, needlessly and loudly. I connected the VSS to get a valid road speed and also identified the wire for the fan activation. Not all PWM fan controllers will work, it needs to be one that works on a PWM negative signal. More ground=more blowing. Fortunately, the e46 has a nice little module built into the fan cassette.

Luckily, I had a bracket laying around that fit the module perfectly and mounts it on my stock fan frame that now has my Spal fan. BMW seems to want this prominently in the airstream so tucking it behind the headlights wasn't an option. I sourced the body side of the harness that the fan plugs into, and I could almost have literally just replaced the e30 plug with the e46 plug, it fits that well.

The e46 module gets wired to the battery and is controlled by the PWM signal. Since the stock aux fan has both a low speed and high speed power wires, I just combined those two together and used them for power. Those wires are connected to two relays that are controlled by the thermo switch, so I shorted the harness at the thermo switch so both relays energize with ignition.

In practice, it works perfectly.

[nando]

Yeah, TBH you and Steve have done a lot already. IMO - if we just had some kits, or even CAD files - people can figure it out from there (or hire somebody who can weld, which I'll probably do, lol). If you try to make these to sell as whole kits, that's a whole different nightmare that I doubt would ever pay off. I seem to spend most of my time working on other people's projects, which is part of why I haven't really done anything for my own E30 since swapping to Megasquirt 3 in 2011.

[hubcapboy]

So, when are you gents gonna offer a mount and oil pan set up for us... less able persons? ;]

I have Habla lined up as the next guinea pig because he's local and has been following along, but we haven't nailed down when he actually needs pieces and how much fabrication he'll need to do. If/when we go through with that I'll show off what changes hands and how it gets delivered. I've been leaning towards a "u-weld-it" kit where everything comes bent and tacked so the geometry is locked down, but details like the drain plugs and dipstick aren't included, and the finish welding will need to be done.

If you hadn't noticed from the timeline and Steve pulling ahead, I've got a job and kids that are really stretching this process out, so I'm not going to be going into production in the back yard.

[Bored]

So, when are you gents gonna offer a mount and oil pan set up for us... less able persons? ;]

[hubcapboy]

Is the fitment really that bad? nah. but the connections are pointed in the wrong direction. There's plenty of room to "do a thing." Even if that was a tight formed 90 off the existing hoses it would probably fit, but it would be close. (There's two hoses, one above the other, where you see the hose clamps behind the C101)

I'm not concerned about the core age, but I am concerned about the life expectancy of my control valve and I don't think the pricey e30 replacement is expensive because of some superior design. Swapping to a Z3 core looks like the easiest way of attaching some standard hose to a core.

Regarding abandoning the 3-stage... Power between 2200 and 6900 is exactly what I want, and 250 whp sounds dandy. If there were zero fitment issues I would probably pick this intake over power above 7000 rpm. That combined with the possibility of having an A/B dyno between my car and Steve's on the same day with the only real difference being the intake is very intriguing.

[nando]

I have a few irons in the fire but nothing to report back with conclusions on... So I've moved back to research. I have a problem to solve related to the location that the heater core pipes pass through the firewall. This shows up in post #96 on page... 7. It wouldn't be impossible to put elbows on the end of the existing lines (I don't think) but I've started thinking about the age of the heater core and heater control valve. Heater control valves are a limited commodity and are prone to leaking and heater cores have finite lives, but the only reason we're bound to these parts is they physically fit and the connections work with the other parts in the chassis.

This is the heater core from a Mitsubishi Montero:

I don't have this or an e30 core in my hands, but from dimensions I can find online I believe this will fit in the heater box with a modified cover on the drivers side (it should be slightly smaller and can be padded out with foam and aluminum tape). This would give us hose fittings to run out through the firewall and locate a heater control valve under the hood. The operation of the e30 one doesn't seem to be magical... it's just an NO solenoid valve that closes if your temperature knob is below 20 degrees rotation.

Even if the new valve leaks... it wouldn't be on your foot?

FRUSTRATED EDIT:

https://www.pelicanparts.com/BMW/tec...eplacement.htm

40 min of scrolling through heater core specs to find that one, and 5 min after posting this looking for a photo of how the heater core inserts for people who might not know I learned that the Z3 setup is EXACTLY like this and has the heater control valve under the hood. I can't find dimensions for the Z3 core, but it looks like the coverplate layout is the same as the e30... I really, really wonder if it even points the hose quick-connects to the same firewall penetration

I still have the original heater core in my E30. If a new replacement lasts just as long, I'll probably be dead, or unable to drive my E30 any longer, before it needs replaced again.

Is fitment it really that bad with the 3-stage? It's a great feature to have on the N52, as you know, my DD is a 330i - and it's fun even at 3400lbs! But honestly, I'm not sure it's worth the hassle in an E30. You get more peak torque and sooner, but the E30 is a good 800lbs lighter than the 330i or 328i. It gets worse as you add AWD, automatics, and convertibles. Even with the N54 manifold, which is hardly optimized at all and basically just happens to bolt in - you only lose maybe 10 ft/lb of torque. It's still way over what any stock E30 powerplant put out, and it can actually make more power at higher RPM.

There are some downsides to the 3-stage that I don't think many realize - aside from cost, complexity and fitment, you're limited to the exact powerband that it's tuned for - ~2200 to 6900rpm. You're *never* going to break ~250whp with the 3-stage manifold. It's not physically possible. The "3 stage" name comes from the 3 resonance frequencies it's tuned for, which are activated at different RPM by the DISA flaps (~1700-3200rpm, 3200-4500, 4500-redline). But unfortunately, after the 3rd stage, this highly tuned manifold cause a *negative* resonance. Torque drops off like a cliff above 6900rpm, making it pointless to rev higher (even if you can make the rest of the engine breathe, which you can). It's frustrating and basically insurmountable (and I've tried everything).

The irony is the N52 actually loves to rev and has a head design bested only by the S motors. All those light parts, tight tolerances, and a free flowing head based on the S54.. stuck at 7000rpm or less. :( Remove that bottleneck, I don't see any reason why 300bhp isn't possible - it just takes more revs than you can get with the 3-stage manifold.

And even if you don't want an 8000rpm screamer, is it worth the 10 ft/lbs to reinvent the wheel on heater core replacements? I'm not sure. There are other considerations, such as the external CCV used with the earlier motors (not sure how that works with the N54 or other custom manifolds?).

I don't want to change your mind at all, I've gone back and forth on this myself and still am not totally decided. Just something to consider - and you've actually driven Steve's car (which isn't fully optimized yet!).

I still want to make my S54 ITBs work though. I actually made progress on my adapter, then I got busy, and then my 3D printer died.. lol

[Habla]

I’m getting all kinds of wild ideas now, since I have the entire car. Do I keep the whole heater box? Blower motor changes from under the glovebox? Yes please. Hell, dashboards are so expensive now, ive even considered whittling down the e90 one and put that in there with the cluster 😅

If the aux fan was a pusher, I would use it as is, but I could at least use the controller setup with a spal fan in front.

Excited to cart the pos into the shop and start harvesting.

[hubcapboy]

I have a few irons in the fire but nothing to report back with conclusions on... So I've moved back to research. I have a problem to solve related to the location that the heater core pipes pass through the firewall. This shows up in post #96 on page... 7. It wouldn't be impossible to put elbows on the end of the existing lines (I don't think) but I've started thinking about the age of the heater core and heater control valve. Heater control valves are a limited commodity and are prone to leaking and heater cores have finite lives, but the only reason we're bound to these parts is they physically fit and the connections work with the other parts in the chassis.

This is the heater core from a Mitsubishi Montero:



I don't have this or an e30 core in my hands, but from dimensions I can find online I believe this will fit in the heater box with a modified cover on the drivers side (it should be slightly smaller and can be padded out with foam and aluminum tape). This would give us hose fittings to run out through the firewall and locate a heater control valve under the hood. The operation of the e30 one doesn't seem to be magical... it's just an NO solenoid valve that closes if your temperature knob is below 20 degrees rotation.

Even if the new valve leaks... it wouldn't be on your foot?

FRUSTRATED EDIT:

https://www.pelicanparts.com/BMW/techarticles/BMW-Z3/105-WATER-Heater_Core_Replacement/105-WATER-Heater_Core_Replacement.htm

40 min of scrolling through heater core specs to find that one, and 5 min after posting this looking for a photo of how the heater core inserts for people who might not know I learned that the Z3 setup is EXACTLY like this and has the heater control valve under the hood. I can't find dimensions for the Z3 core, but it looks like the coverplate layout is the same as the e30... I really, really wonder if it even points the hose quick-connects to the same firewall penetration

[hoveringuy]

On cooling...

So on my M54, as it was on the M20, I had a fixed 80C thermostat, which means my coolant temps ran somewhere around 90C/195F and my radiator outlet temps were around 82C. I had the standard 91C/99C aux fan thermostat switch and a SPAL pusher fan.

In normal driving the temp gauge was somewhere just to the left of 1/2 and if I was in slow traffic or at a light it would creep above 1/2 and trigger the aux fan low speed. All was good. (BTW, I never, ever had an issue cooling the M54 with the stock radiator, even tracking on hot days...)

The N52, however, is completely different...

I've had the chance to drive it a bit now and observe its quirks. First, it has a 97C thermostat which means that normal operating temp is around 105C/220F and it can also slip into "eco" mode.at 112C/234F or down to 95C, depending on what I'm doing. So, the gauge can be settled at 1/2 and then spontaneously start moving to the right if I'm not hooning it. it's kind-of disconcerting and probably why the modern temperature gauges just tell you that things are "normal".

Anyway, this means that with an operating temp of 105 my radiator outlet temp is around 95-97C, which clearly triggers the aux fan. Sometimes I even trigger aux "high" at 99C.

What seems to happen is that the aux fan and the ECU end up fighting each other. The aux fan kicks-on to drive down temps, but the ECU is determined to raise them so it just reduces coolant flow. The aux fan ends up running all the time, even at highway speeds.

So, I need the aux fan and the ECU to coordinate with each other. If only there was a way to do that...

To start, I connected C101 pin 14 VSS with 6001 pin 17 speed input and verified that the ECU is registering road speed, I think that's a critical parameter in how it controls the aux fan. I put the car on jackstands and at 40mph the
Geschwindigkeit was 63kph. Sweet!

Next, I need to see about getting an aux fan module and seeing how that integrates with the ECU and the SPAL.

As a final note, early N52's have a radiator outlet temperature sensor, but the later N52K's do not. I think the later motors just assign an outlet temp that's 7.5C lower than inlet. Since my flash isn't necessarily from a late motor, I may or may not need to add the outlet temp sensor to make everything work...

As a final, final note, the cooling parameters have tables and can be mapped like anything else, so there is a degree of software control that's available, but I'm not sure how I would change it.

For documentation, this is the PWM fan signal. It's a 5v signal that's pulled down to ground (open collector), 100Hz. This is 15 percent duty cycle. Some PWM fan controllers are setup for this signal and some are reversed polarity, where duty cycle is time at 5v instead of ground..

[nando]

hours.. there's so much shit in the way. you can't really even fully access the head because the wiring harness runs right over cylinder #5.

[hoveringuy]

It's funny, because in a much smaller car - the engine is actually way more accessible and easier to work on than it was originally.

I can have the valve cover completely off in under 20 minutes (done that 3x now..), or have the electric water pump pulled in about the same.

How long would that take in an E90?

With the N54 intake I'm staring at the starter and the heater core connections are out in space

[nando]

It's funny, because in a much smaller car - the engine is actually way more accessible and easier to work on than it was originally.

[hoveringuy]

See, isn't this better already? That long X3 harness is going to be replaced by one from a Z4, which exits the back of the engine instead of the side. It's going to look great, trust me.