N52 Swap Discussion

[hoveringuy]

Let's talk about my weight.

Just crossed the scales at 2460lbs, with a full tank of gas and the almost exact configuration I had with the M54. That's a 23# reduction from M54 to N52. Some other things that changed are aluminum X3 brake booster (-6lbs) and 5" rear springs (-2lbs), so the N52 is around 15lbs lighter than the M54 which includes a 6speed transmission, dual-mass flywheel over the G260 single, and dope S54 headers over the OBD2 manifolds. (plus I have beefy steel engine mount arms, a steel oil pan that can double as a skid plate, and hydraulic engine mounts.)

Replacing my passenger seat with a Sparco, deleting rear interior (because I won't be able to get people back there, anyway...) and maybe a CF hood would easily get me below 2400.

[hoveringuy]

My fuel pressure was 6 psi short of 5bar, and my stock fuel pump was very noisy, so I installed a new Douchewerks DW200 with the 9-1031 install kit. This is supposed to flow 210 liters per hour at 5bar while drawing 11 amps.

For the install you're supposed to just use a hose clamp to attach it to the support rod, but I didn't think that was secure enough and added a bracket, because I love brackets. I also didn't use the supplied accordion flex line and used fuel line instead. My other hints are that the pickup was hitting the bottom of the tank if I lowered the pump all the way to the bottom, and the position of the clamp is important so that it doesn't hit the fuel transfer tube inside the tank. The filter sock was clocked to the correct position for the tank, however.

It's quieter than my stock pump and boosted the rail pressure.

[hoveringuy]

I haven't had cabin heat up until now and was getting tired of cold feet, so I finally plumbed it up. Some things are different on the N52, but the primary cooling loop is basically the same. Hot coolant leaves the engine, flows through the radiator, is metered by the thermostat and then pumped back into the engine. I fabricated a small manifold to tap the engine outflow and send it to the bottom pipe of the heater core.

It absolutely sucks!

No warm air even when at operating temp at idle. I did get a small amount of hot air when I did some driving. What's going on?

As an experiment I triggered the coolant pump to 95% through INPA once I was back in the garage and got a plethora, a veritable gusher of hot air. Like, a lot!

So, I think what's happening is that the engine doesn't know that I'm trying to make heat and runs the coolant pump at low speed which isn't pushing anything through the heater core. Need either 1) an aux heater circuit circulation pump or 2) a way to tell the ECU to ramp up pump speed for heat.

[hubcapboy]

Huh look, the Mercedes SL heater control valve I bought to experiment with relocating the valve to under the hood has an aux pump attached to it:

[hubcapboy]

Mercedes uses the aux pump to circulate coolant and provide heat when the engine is off but still warm.

[Caperix]

The bigger cars, use a aux water pump to help circulate coolant, even the e60 with a n52 has one off the upper radiator hose. It is adding a potential failure point, though most just drip when they leak. Are you using a can translator board? You would need to find what code the ihka sends to the dme but it should be doable. I know m54 z4's were available with the low ihkr HVAC system in the us, I don't know if that continued to the n52 cars but it should have much less communication involved.

[nando]

There probably is a CAN message from the HVAC system to tell it when you're heating the car. There must be a way to force it to flow a minimum amount of coolant or some other way to tell it you're using the heater. I have never looked at that because nobody has ever mentioned an issue with heat, but it seems pretty important!

On the N52, it uses the electric pump itself to heat the cabin with the engine off (the "rest" function). We have full control over the DME, so I don't see why it couldn't be made to work.

[nando]

Looked into the heat situation and I think the solution is pretty simple (at least as far as work-arounds go). No external pump is needed, indeed that would be silly as the waterpump can flow regardless of if the engine is on or off (N52 cars even have an HVAC button specifically for this). I haven't looked but I sort of doubt that E60s with the N52 have a separate pump just for that when the stock N52 pump can already do this.

I took screenshots of the pump operation in 3 states - at idle with the heater at full blast, the heater off, and also with the engine off and the heater on max (REST). That should tell me the typical states of the waterpump operation regarding heater controls.

here's the heat turned off - minimum pump speed is 15% at idle:


here's the heat set to max (84 degrees) - pump speed is at 76%:


Here's with the engine off, and the heater at max (REST) - pump speed is 35%:


Now, the pump is controlled with thermal load. There's not really a map, but a set of constants
(K_EWP_*). the DME uses demand to decide how much to operate the pump on the fly. All are in units of liters/hour - the N52 pump has a maximum capacity of 7000l/hr:


Suffixes:
MN = min - the minimum pump flow with the engine warmed up.
MX = max - the maximum pump flow
WA = warmup flow rate. Notice the pump is turned off entirely during warm up. This helps to warm up the engine faster.
MN1 = This is the min pump flow at start with an already warmed up engine. We probably don't care about this, it's just designed to get the coolant flowing until the engine is in a "normal" state (there can be hot pockets when you turn off a hot engine etc).
AP = it's not actually clear from the code or the description - but I think this is the base flow rate for using the REST position

So basically, I think if we increase the K_EWP_MN to about 2000l/h, that should give us about the minimum speed needed to run the heater. This is a workaround without needing CAN inputs of course - and it would be easy enough to switch this value back to stock for a "summer" tune.

Also I found this interesting - this is the map for running the pump while bleeding the coolant system:



The Y axis is pump flow and the X axis is time (not sure of the exact units, probably CPU cycles or something). If you've ever bled an n52 engine before, this graph will make a lot of sense..

[hubcapboy]

Looked into the heat situation and I think the solution is pretty simple (at least as far as work-arounds go).

This is outstanding. I just walked over to my harness and clipped out the relay for the aux pump. I'm not stressed out about having the pump idle at 35%; these cars were sold and run in the desert... The duty cycle of that pump isn't a concern. The only compromise to the original design is potentially we'd be sucking enough heat out of the engine that it wouldn't be able to reach it's "super hot" eco operation temperature, which I'm completely fine with.

I've been physically modifying my Z4 harness to incorporate the oil level sensor, tesla booster power, gauge temp sensor, tap the oil pressure switch, add the C101, incorporate the Z4 IVM, add a sport button, an L-Can connection for an OBD reader (TBD if that works), an OBD plug, the accelerator cable, and a dash cable that will carry the cruise control wire, brake pedal switch, clutch switch, tach, wheel speed, and econometer signals between the DME and drivers side. I've also lengthened all the connections on the intake side using a spare X3 harness so that the DME can reach the glove box.

Most of that has been discussed, but the instrument cluster temperature gauge has some new developments. hoveringuy is happily using his original e30 temp sensor in a new bung on the oil filter housing to drive the gauge, and it seems to be indicating for him perfectly. An easier way of doing this is to put a sensor housing in-line with a hose. For some reason I'm not really thrilled about either of these, and after figuring out that my e36 dual temp sensor wasn't going to work in the last 24 hours (it's a four plug sensor with the correct thermistor for the ECU and a second sensor for the gauge... but the resistance values are wrong... I thought I could correct them but it can't be done passively) I've gone in a completely different direction which may or may not work out.

We can get numerical coolant temperature from the DME, and the DME is constantly doing weird stuff with coolant as we found out with the heating issue and the fan switch vs thermostat feedback loop. Watching that needle jump up and down as the DME makes different decisions about what to do with the coolant is as uninformative as using the charge light to indicate if the N52 alternator is charging... Every time you put your foot down, the DME turns off the alternator, and it would look like a fault on the dash.

Instead of measuring coolant level, I'm going to try and use the sensor to measure Head temperature. Garageaholic has a video where he measures the temp gauge's response to different resistances, and his profile of the gauge looks like this:

Gauge Position	Indicated at
	Ohms
End	325
Blue Start	122
Low Line	70
mid	42
High Line	31
Red Start	22
End	14

Through a lot of poking around, The 1k model of this thermistor:

https://www.tdk-electronics.tdk.com/...be_ass_K45.pdf


will present 87 Ohms at 98.6 degrees, which is right around where I think I want the middle of the gauge to be. Using fixed resistance to adjust that creates the same problem I was having in correcting the e36 sender... That since the resistance you're adding is fixed and the sensor is logarithmic, you only see your fixed resistance for a large part of the scale. Using two of these thermistors connected in parallel does two things... It lets you sample (and electronically average) two locations, and it brings the resistance at 98.6 down to 43.5 Ohms... which will read just a little below center on the gauge. Here's the whole table of temperatures I expect to indicate at the different points of the gauge:

Gauge Position	Indicated at	Temp C
	Ohms	2 in ||
End	325	35.6
Blue Start	122	62.9
Low Line	70	80.6
mid	42	98.6
High Line	31	110
Red Start	22	124
End	14	144

I haven't tracked down a good spot to fix the M3 studs, but probably one towards the front of the head and one towards the back.. This will give the actual head temperature (not the coolant temperature, which is a stand-in for that) and won't jump around as thermostats open and close and electric pumps decide to change speed. Even if it doesn't read dead center at operating speed, it'll be good feedback on engine temperature.

[hoveringuy]

I received my Plan B in the mail today. (maybe that didn't come out right?)

Anyway, I received my Mercedes aux pump. It fits into my coffee mug and pumps a measured 1600 liters/hr. Dead silent.

Here's the mind-blowing part. 1600 litres per hour is 23% of 7000 litres per hour, or the main coolant pump running at 23%. So, 2000 liters per hour will cover this pump and plenty for flow through the radiator.

It probably won't go in the car but the Koi love it!

[hoveringuy]

First track day of the year! So how did it do?

First, Nando, was nice enough to update the tune to both make the water pump run slightly faster, so I had cabin heat, and fix the radiator outlet temperature so that the aux fan worked properly and I had cooling. Both of those worked GREAT.

Overall, the motor was down on power from the M54 I had last year. My speed at the end of the straight was down from about 129 to 124 and it didn't pull as hard out of the corners. The M54 dynoed at around 245 so I'm guessing it's at 225-230whp presently. Power also got a little flaky after about 6200 and it didn't pull as hard on the top end as it should. It also used a lot of gas. I could run four 11 lap session with the M54 and still have gas to drive home; the N52 left me on "R" at the end of the third session.

So, the motor is running in limp mode, which means that the timing has probably been pulled back quite a bit which explains the power and probably the gas, too. This will be fixed.

The good news is that there were no other hiccups. The temp was about one needle width to the right of 1/2. No oil pressure issues, ZERO leaks. No banging, exhaust clearance or header heat issues. Started instantly, idled smoothly, sounds awesome! My driving was splendid, obviously.

On deck: I'm pulling the entire engine wiring harness and swapping in a Z4 harness and IVM that will clean things up considerably. Once that's done the final hurdle is for Nando to figure out the maps and braniac stuff to make it run right.

[Bmwtech07]

This is great progress! Has anybody committed to a group buy on the oil pan? I'd buy 2! I have access to a parts ix, has anybody confirmed fitment on the ix setup without modifying the pan? Is there any progress with the tesla booster? I've done the s52 swap. It seems only logical my next build be an N52.

[nando]

You definitely need to modify the pan for the ix I have a bunch of spare pans and an aluminum flange that these guys had made for me, it's a matter of cutting up the stock ix pan, making a jig, and welding it to the new flange.

Actually, if you converted the ix to RWD, the stock N52 pan fits perfectly, lol, but a RWD converted ix is a waste of time...

[hubcapboy]

Steve's track day shows a remarkable level of dedication to shake-down. He might credit it to luck or some inherent quality of the engine that he made it a full day, but I know how this guy drives and he's pushing it.

It's pretty remarkable that on the Rev 1 of most of this stuff that he could cane that thing around a track for a full day and not run into a lubrication, cooling, interference, or fueling problem.

Regarding getting these swap kits into everyone else's hands, I'm reluctant to start releasing parts until we have at least one car fully sorted (now that Steve's is so close... maybe two... which would hopefully include mine). At the moment the parts we've designed are:

-Oil Pan
-Sump baffle
-Engine Arms
-Subframe adapters to take e46 motor mounts (mandatory... the engine arms are designed to mate to these)
-330i 6-speed transmission mount (not needed if you use the lighter duty 328i 6 speed... it's short enough to use the factory e30 5 speed bracket)
-OIl pickup adapter
-Oil pickup mount

I don't think it's realistic (for me, right now) to sell this as a no-welding-required kit unfortunately, There's too many variables for me to guarantee/customize each instance, and I introduce even more if I add the cost of having someone else assemble them. I think the best case right now is to expect that these will be tacked together to define geometry so that you can DIY the structural welding and seams on the pan and include all the features in the location you want (PCV drain, dipstick, sump drain, oil level sensor, it's more than you'd think).

I had a big push a few weeks ago and it strained things around the house and I've been holding off now... so progress has not been great. We have at least one more local swap in progress that I'm happy to support, but beyond that I'm waiting until we can confidently say "at least one way of doing everything is figured out," because I don't want to deliver a bunch of parts and have a group of people waiting for the next news.

[nando]

There are still some things to sort regarding tuning as well. I actually think there's nothing wrong with Steve's calibration, but the adaptation for valvetronic is "stuck" because we switched from a Z4 based tune to an E90 330i base (but with the CAN bus set to the older, E46 generation protocol). It's possible that some of the other adaptations are "stuck" as well, explaining the poor fuel economy and low power. His calibration is actually nearly identical to the one I use on my daily driver - the main difference is he has headers and the N54 manifold, while I have a 3-stage and MILVS with stock exhaust.

Similar to how I got the external temp sensor to work again (I think it was stuck in some sort of diagnosis loop), I need to "unstick" the adaptation routine for his Valvetronic. I have some ideas to force it and hope to get it done this week.

It's possible I could also do it by writing an E90 eeprom directly to his DME. The eeprom is where all adaptations and things are stored when the car is off. BTW, this means that "unplugging" the battery will not reset anything - errors, adaptations, mileage, coding etc - it's permanently stored in the eeprom. But the stored "adapted" values between the Z4 and E90 are different, which I think caused the issue with the radiator outlet temp and Valvetronic. Unfortunately, the only way to write to the eeprom is directly - with BDM, requiring physical access.