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Discussion Starter · #1 ·
I'm not sure if anyone has really done a thread like this, so here goes. :thumbsup:

I wanted to just put to pictures a very general overview of what's going on under the bonnet of the F56 in terms of component location and the general technology involved.

Step 1: Open the Bonnet. MINI is using a new style latch where you do a "double pull"; once to unlock it, and another pull to release it. No more fiddling around by feel to find that latch that's never where you left it. :wink: :razz:

IMG_7400.jpg by Ryephile, on Flickr
-->Note: I had just washed the car, hence the rusty rotors.


Here's what we get: an engine bay shot.
IMG_7404.jpg by Ryephile, on Flickr


On the underside of the bonnet, we have the stickers that show what legal standards the car abides by:
IMG_7399.jpg by Ryephile, on Flickr


If we give a firm tug to each of the 4 corners of the MINI branded engine cover, here's what the underside of that looks like. Thick acoustic foam quiets the sound of the direct injectors and high pressure fuel pump.
IMG_7403.jpg by Ryephile, on Flickr


Here's the exposed valve cover of the engine. Just to point some things out, starting at the middle top with the foam block with the two cables coming out of it, that's the high pressure fuel pump. Clockwise from there, the diagonal tube is the induction pipe going from the air filter to the turbo compressor inlet. Clockwise from there is the big fuzzy box with the red cap, that's the environmental box for the battery, power distribution, and engine control unit (ECU). Then we have the airbox itself, with fresh-air duct connected to the front bumper. We'll get to the rest shortly.
IMG_7394.jpg by Ryephile, on Flickr

Going further on this picture, there are four parallel lateral lines between the valve cover and the intake manifold. The upper one is the low pressure fuel feed line. The next one down is the wiring harness for the Valvetronic servo. The third one down is the evaporative emissions vent hose and solenoid coming from the fuel tank and charcoal canister, and the bottom line is the +12 volt positive cable from the battery to the alternator to the starter.


To be continued...
 

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Discussion Starter · #2 ·
Zooming into the engine itself a bit. Center of the picture is of course the oil filler cap. Bottom center of the picture is the wiring connector for the Valvetronic servo. This is connected to a 3rd camshaft [yes really] that controls how much valve lift the intake valves achieve. This is controlled by the ECU's complicated algorithm to maintain minimum pumping losses across the valve head. The result is a typical MAP of 90kPa, unless turbo boost is being used. Also visible in the lower left of the picture are the two Air Conditioning refilling ports.
IMG_7396.jpg by Ryephile, on Flickr


Pushing in a little more from the last picture, we can see the coil-on-plug's, the fuel rail, fuel rail pressure sensor, and two of the piezo fuel injector wiring harness plugs. In the upper left are the two crankcase ventilation hoses.
IMG_7397.jpg by Ryephile, on Flickr


Ok, switching areas, to the air filter, or "intake muffler" as they're called now. Here is the stock paper filter. Paper is used by OEM's because it's affordable and does a fantastic job filtering small particles. Here, with 72 3-inch tall pleats and a 9.625" average width, this filter has an astounding 2,079 square inches of filter surface area. That's awesome! It will take a very free-flowing [and subsequently not very effective at actually filtering] for the aftermarket to get more filter area in the car.
IMG_7424.jpg by Ryephile, on Flickr


Here's the dirty-side of the airbox. More importantly, the clean-side of the airbox with its reservoir of clean air is important for transient response.
IMG_7423.jpg by Ryephile, on Flickr


Here's the clean-air side of the airbox, detailing the quasi-velocity stack right in front of the mass-air flow (MAF) sensor. This sensor has a direct correlation to how much power the engine is making, which then makes for very nice OBDII datalogging. The smooth radiused inlet reduces turbulence and makes good power.
IMG_7422.jpg by Ryephile, on Flickr
 

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Discussion Starter · #3 ·
...and the final chapter for now...

Here are the two panels you have to remove to service a whole bunch of things. The brake reservoir and booster, the ECU, the battery, and power distribution.
IMG_7425.jpg by Ryephile, on Flickr


With those popped off, here's what it looks like underneath. The white box on the left houses the ECU.
IMG_7426.jpg by Ryephile, on Flickr


Here's a close-up of the battery. Indeed it says "AGM", which means Absorbed Glass Mat design. That would make it a non-spillable battery. 80 Amp-hours is a big capacity, likely to help with the Stop/Start engine operation.
IMG_7427.jpg by Ryephile, on Flickr


The wiper motor is situation above and aft of the battery. Also note the negative battery terminal's strange shape; it uses a pyrotechnic device to disconnect the battery in a collision, greatly reducing the chance of fire.
IMG_7430.jpg by Ryephile, on Flickr


Was this helpful? What topic or area would you like to see expanded on?
 

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Nice write-up. Now I know where the battery is!

This belongs in the Engine Section when we get one.

You must have Engineer genes.....gotta take things apart to see what makes things work! That's a compliment! :)

John

P.S. By the way, Varta has been around in BMW's for decades! Really solid batteries. My 2002's originally came equipped with Varta batteries back in the 70's!
 
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Doesn't look like the new MINI engine bay is very conducive to the addition of a strut brace either. If so, I'd like to see one installed in there! :)
 
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Discussion Starter · #7 ·
Doesn't look like the new MINI engine bay is very conducive to the addition of a strut brace either. If so, I'd like to see one installed in there! :)
Thanks for the engineer compliment. :D

Actually I was just looking at that with a friend yesterday. It does appear there's room between the rear bonnet seal and the red cap of the battery positive terminal. You'd have to cut apertures or slots into the bonnet seal to make it work.

That said, with each successive generation of MINI getting even stiffer, a strut tower brace might not be the low-hanging fruit it once was. It would nevertheless add some engine bay eye candy.
 

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Discussion Starter · #9 ·
You would think using a pyrotechnic device under the hood would be a sure way to start a fire. Hmm.
Thanks for the tour.
You're welcome!

Airbags don't start fires. Same kind of device, except is disconnects the battery terminal. Hence the phrase pyrotechnic, as in intentionally designed to do a specific thing, not just randomly go KA-BLAMO.

As another example of the rigorous engineering that went into the car, outboard of the battery is a molded rainwater drain duct that transports water from the windscreen and cowl into the backside of the fender liner down to the bottom of the car. That's just one example how Water Management and engineering in general is on a higher level with the F56 than generations prior.

Another example is how the valvetrain timing chain is a 2 chain design and is located around the flywheel between the engine block and the transmission, thematically similar to that of a motorcycle. This design allows for a narrower engine design, giving more room for a strong chassis and optimized crash protection.
 

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Thanks for the engineer compliment. :D

Actually I was just looking at that with a friend yesterday. It does appear there's room between the rear bonnet seal and the red cap of the battery positive terminal. You'd have to cut apertures or slots into the bonnet seal to make it work.

That said, with each successive generation of MINI getting even stiffer, a strut tower brace might not be the low-hanging fruit it once was. It would nevertheless add some engine bay eye candy.
Nice write-up.

Just FYI, NM Engineering makes a strut tower bar/brace for the Fxx.

http://www.nm-eng.com/338/0/0/3181/nm358846-nm-eng-billet-aluminum-tie-bar.html#popUp[products]/3/
 

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Discussion Starter · #12 ·
Nice write-up.

Just FYI, NM Engineering makes a strut tower bar/brace for the Fxx...
Thank you! :) I see the NM bar goes fore of the battery terminal.

I added arrows and descriptions to some of my pictures. I intentionally labeled some of the same things in different pictures to retain perspective. Hope this helps!

engine1notes by Ryephile, on Flickr

engine2notes by Ryephile, on Flickr

engine3notes by Ryephile, on Flickr

engine6notes by Ryephile, on Flickr

Cheers,
Ryan
 

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Awesome Ryan! That belongs in the Owner's Manual, but then MINI would be giving owners too much information! :)

I'm sure I speak for everyone that "we appreciate your efforts explaining & describing these functions under the bonnet"!

You are a certified "Miniac"! :D

Cheers,

John
 

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Discussion Starter · #16 ·
You guys ready to raise the bar? Ok, let's start by looking at some OBDII datalogging!

First step is to get yourself a nice little On Board Diagnostic-II interface and some PC software. I use simple but effective software called OBDwiz and an OBDLink SX scan tool cable, that connects from the SAE J1962 standard connector and pin-out to your PC's USB. On the MINI's, the OBDII connector is right above your feet in the footwell of the left side [driver for USA & EU, passenger for UK & Aus].

For the full scoop on OBD and its history, Wikipedia has a solid description.

Ok, so what comes out of this is the interface allows you to read all the sensors the OEM outputs onto that bus. Things like engine RPM, Manifold Absolute Pressure (MAP), Mass Air Flow (MAF), ignition timing, coolant temperature, intake air temperature, Oxygen sensor, and a whole host of other sensors, calculations, and outputs. The Scan-tool also allows you to read and clear OBDII "check engine" light codes, including observing the "freeze frame", which is a snapshot of what the engine was doing at the time the ECU posted the check engine light code.



Let's take a look at some basics. Here is a 13 minute cruise during my morning commute. Most of it is cruise control on the Interstate, in 6th gear at about 2,900 RPM. There are 4 attributes being shown here: MAF, MAP, Wideband Oxygen sensor, and cylinder #1 Ignition Timing.
datalog1 by Ryephile, on Flickr

Don't worry about looking at it too hard. If it looks like greek, that's ok, it's not terribly descriptive with so much data being shown over such a long period of time. If you look closely at around the "1400" mark [timestamp on the datalog], you can see that the MAP and MAF both spike. That was me tipping in to get some passing power. Looking at the exact CSV data cells, that ended up being about 110 HP at 2300 RPM with 10.5 PSI of boost, and an inferred G100 Air-Fuel Ratio of 14.1:1, or Lambda 0.96 actual. Making some assumptions about Brake Specific Fuel Consumption, that equates to about 251 Lb Ft of torque.



Ok, I lost you. Come back! This next graph is more interesting.

datalog2 by Ryephile, on Flickr

This one shows a different time region than the above one, and this time it's only 15 seconds long, in 4th then 5th gear, and me flooring it in the middle of the graph. This allows us to see more detail. This graph shows more sensors, MAF, MAP, Lambda, ignition timing, commanded torque request, and engine RPM. I fiddled with the scales on RPM and Lambda so they had more resolution. For Lambda, the middle of the graph correlates to Stoichiometric, or 14.7:1. Lower on the graph is richer, and the top of the graph is free-air during fuel cut.

You can see that from the left of the graph I was just cruising along. Then the commanded torque goes to 100, the boost rises, the air flow rate increases because the engine is making more power, and the ignition timing retards to minimize knock and get rational combustion for the given torque. This was in "Mid" mode, and at 3900 RPM the engine ended up making about 170 HP, or about 229 Lb Ft of torque. This was also downhill on an on-ramp, so the ECU calculated I didn't need as much torque based on that and my pedal rate of change being reasonably lazy. The torque calculation is very complicated, as we can see. The engine doesn't make a fixed boost level, but instead calculates how much torque you really want and adjusts the boost, throttle body, Valvetronic servo, intake and exhaust cam phasing based on all the sensor inputs.


Clear as mud? Oh one last thing for now. Once the engine is up to temperature, it appears to settle at about 224°F coolant temp and 215°F oil temp. This is totally normal for current cars.
 

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Discussion Starter · #17 · (Edited)
Ok maybe I jumped the gun a bit. Let me step back and explain how our B38 and B48 engines work before going deeper with the datalogs. Here are the fundamental bullet points for the B38 3-cylinder in the Cooper, and the B46/B48 in the Cooper S and JCW:

*500cc per cylinder, giving shared piston, connecting rod, and valvetrain components across the family line-up.
*Cast Aluminum cylinder block, cylinder head, and oil pan. High-temp plastic valve cover [quieter than aluminum].
*three camshafts, one for intake, one for exhaust, and one for intake valve lift actuation [Valvetronic]. Phase adjusters on intake and exhaust camshaft [Double VANOS].
*4 valves per cylinder, two intake and two exhaust. Exhaust valves are sodium filled for improved thermal capacity during long-term stresses like going to the racetrack.
*Bosch MEVD 17.2.3 engine control unit using Infineon's Tri-Core microcontroller, with CAN, and Ethernet. A veritable supercomputer under your bonnet.
*Direct injection using current-gen piezo injectors, centrally located for very precise fuel injection into the piston "bowl", improving the stability of stratified combustion. High pressure fuel pump driven off exhaust cam extra lobe.
*fuel delivered from tank by a returnless single line system
*Single knock sensor mounted centrally between cylinders 2 and 3. Fast response Wideband Oxygen sensor [maybe LSU 4.9, TBD]. Very high density crank tooth wheel, tooth count TBD. MAF, MAP [in intake manifold], and T-MAP [upstream of throttle body] contribute to a highly developed efficiency optimized torque targeting algorithm instead of old school fixed maps.
*structural high-temp plastic intake manifold
*vacuum pump built into cylinder block for consistent brake booster operation during boosted engine operation.
*cast exhaust manifold & turbocharger turbine as one piece. Coolant cooled and oil lubricated CHRA. Electro-pneumatic wastegate operation, electronic diverter valve operation. 3-cylinder gets a single-scroll turbine, 4-cylinder gets twin-scroll turbine.
*twin counter-rotating balance shafts to damp engine resonances.
*two timing chains; one from crank to idler, and idler to both camshaft sprockets. This is routed around the front-side of the flywheel in order to create a more compact engine.
*two catalytic converters, one close-coupled for primary emissions scrub and a secondary for additional cleaning


What does this all mean? The engine doesn't simply use a throttle body anymore, that's just one part of the equation. Valvetronic uses intake valve lift to also "throttle" the engine. In this 4th gen Valvetronic, the ECU uses both the throttle body and the Valvetronic to target a specific minimum pumping loss across both the throttle body and the valve heads to maximize fuel economy, even at full load. When you tip-in the throttle part way, the ECU is figuring it out in real-time whether to use the throttle body, the Valvetronic, or a mix of both in order to give the perfect torque output with the maximum amount of thermal and volumetric efficiency.

The direct injection system has a few key difference compared to old school small block Chevy's, and even more recent port injection systems. The primary differences are the much improved chemical quench that results from a significantly finer mist of fuel, and the quicker combustion speed due to that finer mist and also the small diameter cylinder bore. All those factors contribute to ignition timing much less advanced than many hot rodders may be familiar with. No more are the days of slow-burn SBC's needing 45° of advance to get decent power. With the new MINI engine, it's looking like between 2 and 14 degrees of advance [BTDC] is all that's needed for correctly timed combustion at full load, and as retarded as -13° BTDC at very low load and RPM. Another benefit of the center-mounted DI system is the ability to run at Stoich, or closer to peak torque Lambda at high loads if desired. This is afforded again by the chemical quench of the fine mist, meaning cool EGT and low component stress. This allows for the boost to be turned up at lower RPM, where knock would otherwise make such high boost/low RPM operation impossible.


Ok, hopefully that helps explain some of the philosophy behind the engine operation in general. :)
 

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This is possibly one of the best threads I've ever read on here. I only recently got into cars upon getting my MINI so to see everything I've been trying to learn broken down into excellent pictures and descriptions is a dream! Thanks for this Ryephile.
 

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Discussion Starter · #20 ·
Ok here's a big one. This is torn directly from tim330i's post in the new BMW F48 X1 section on Bimmerfest.com, I did not put this together, only re-host the pictures. It is very relevant for the MINI because the X1 shares the same platform and engines as the MINI.

The all new F48 BMW X1 is arriving in dealership with an all new engine. The BMW B46 inline 4 cylinder engine replaces the N20 4 cylinder found in the previous X1 as well as much of the BMW lineup. The N20 was a great engine but was not universally loved, complaints diesel like vibrations and engine racket were the prime offenses to American based BMW owners use to the silky smooth 6 cylinder engines.

In a never ending quest for more performance and efficiency the N20 is being retired and the B48 takes it's place. The B46 is part of the new BMW B family of engines, we dive into what makes this 2.0 liter TwinPower inline 4 special.

The new engine generation is mainly characterized by lower fuel consumption and fewer exhaust emissions (ULEV II). To achieve low fuel consumption, a map-controlled oil pump, characteristic map thermostat and injection system with direct-rail and electric arc wire-sprayed cylinder barrels, among others, are used. All engines also receive an automatic engine start-stop function and intelligent alternator control as a further EfficientDynamics measure.

Due to the similarities between the B38 3 cylinder engine and B46 4 cylinder engine some images shown are of the 3-cylinder engine.

TwinPower Turbo Technologies

BMW-TwinPower-Turbo-Technologies by Ryephile, on Flickr

TwinPower Turbo is a commonly misunderstood term, often being confused with twin turbo, especially as it was introduced around the time BMW discontinued the twin turbo N54 engine. TwinPower does not mean twin turbo, in BMW nomenclature it is the umbrella term that means the following technologies are used:
  • VANOS
  • Valvetronic
  • Direct injection
  • Turbocharging

Crankcase / Engine Block Design

BMW B46 engine block crankcase by Ryephile, on Flickr

Characteristics of crankcase:
  • Heat-treated all aluminium crankcase made from AlSiMgCu 0.5
  • Electric arc wire-sprayed cylinder barrels
  • Weight-optimized main bearing cap of crankshaft with embossing teeth
  • Closed-deck design
  • Deep Skirt
  • Oil ducts for the use of a map-controlled oil pump
  • Support of counterbalance shaft(s) in cored tunnel

Closed-deck design
With the closed-deck design, the coolant ducts around the cylinder are closed from above and provided with coolant bore holes. This design is mainly reserved for BMW diesel engines. Due to the high combustion pressures in the diesel engine, a greater degree of rigidity is required in order that the forces can be safely absorbed. As the gasoline engine uses the same unfinished cast part as the diesel engine, it also benefits from this robust design.

Cooling concept of cylinder head
The B46 engine has a cylinder head with cross-flow cooling. In the case of cross-flow cooling, the coolant flows from the hot exhaust side to the cooler intake side. This has the advantage of providing uniform heat distribution in the overall cylinder head. Loss of pressure in the cooling circuit is also prevented.

Cylinder head gasket
In order to satisfy the high demands of the B46 engine, a triple-layer spring steel gasket is used as the cylinder head gasket.

Electric arc wire spraying
The cylinder walls of the B46 engine are coated with electric arc wire spray (LDS). In this procedure a conductive metal wire is heated until it melts. The melt is then sprayed onto the cylinder barrels at high pressure. This layer of ferrous material is roughly 0.3 mm thick, extremely wear-resistant and facilitates an efficient transfer of heat from the combustion chambers to the crankcase, and from there to the coolant ducts

Counterbalance Shafts of B46 Engine

BMW B46 counter balance shafts by Ryephile, on Flickr

Due to the operating principle of the piston engine, undesired oscillations occur at the engine housing when driving, which can be transmitted to the vehicle interior. To counteract this negative effect, BMW has already been installing so-called counterbalance shafts in more recent engine generations. Up till now, their role was to cancel out free inertia forces and therefore increase ride comfort. In addition to the inertia forces, so-called 'free moments of inertia' also exist, which can also adversely effect ride comfort. Depending on the engine design and number of cylinders, varying degrees of free inertia forces and free moments of inertia occur.

The B46 engine has two counterbalance shafts which rotate at twice the speed of the crankshaft. The gears of the counterbalance shafts have 48 teeth. The gear of the crankshaft has 96 teeth.

Timing Chain, VANOS and Valvetronic Components

BMW B46 engine timing chain by Ryephile, on Flickr

On of the bigger changes on the B46 is the location of the cam shaft timing chain drive. Typically found on the front of the engine, the B family of engines has the chain drive on the transmission side. The inertia of the transmission at this end of the engine significantly reduces the rotary oscillations and also therefore the loads acting on the chain drive.

Note the two different chains that make up the cam drive chain. In the diesel engines, the high pressure fuel pump is driven by this intermediary gear setup. On the gasoline engines the high pressure fuel pump is located on top of the engine so a simple gear transfer sprocket is used.

To facilitate VANOS repairs the VANOS solenoid valve actuators on the B46 are not mounted to the cylinder head, but in the cylinder head cover. Presumably the cylinder head cover (valve cover) can be removed to change the solenoid so the entire engine does not need to be dropped. Additionally the mounting of the VANOS solenoid valve actuators has also changed. They are no longer bolted on, but are attached to the cylinder head cover using a bayonet fitting and retaining clips.

VANOS
With older VANOS systems, such as that used in the N55 engine, the VANOS units were controlled by separate VANOS solenoid valves integrated into oil ducts in the cylinder head. The oil ducts in the cylinder head are reduced and the adjustment speed is increased by using a VANOS solenoid valve unit and a mechanical VANOS central valve, which is located inside the VANOS unit.

The valve overlap times have a significant impact on the characteristics of the engine. An engine with smaller valve overlap therefore tends to have a high maximum torque at low engine speeds but the maximum power which can be achieved at high engine speeds is low. The maximum power achieved with a large valve overlap on the other hand is higher, but this is at the expense of the torque at low engine speeds. The VANOS provides a solution. It makes a high torque possible in the low and medium engine speed range and a high maximum power in the higher engine speed ranges. A further benefit of the VANOS is the option of internal EGR. This reduces the emission of harmful nitrogen oxides NOx, particularly in the partial load range

Valvetronic
The Valvetronic has been further developed for use in the new Bx8 engines. A distinguishing feature of the VVT4 is the Valvetronic servomotor is located outside of the cylinder head. Valvetronic comprises a fully-variable valve lift control and a double VANOS. It operates according to the principle of throttle-free load control. With this system, a throttle valve is only used to stabilize the engine operation at critical operating points and to ensure a slight vacuum for the engine ventilation. A very small vacuum can be produced in the intake pipe by slightly tilting the throttle valve, which allows treated blow-by gases to be introduced into the intake port during naturally-aspirated engine operation.

Oil Filter

BMW B46 engine oil filter by Ryephile, on Flickr

Due to the construction space, the oil filter housing is suspended in the transverse mounting. The inspection is carried out from the bottom of the vehicle. Using an oil drain plug the Service employee can drain the engine oil from the oil filter module before opening the oil filter cover.

Cooling System

BMW B46 cooling system by Ryephile, on Flickr

In order to protect the thermally loaded engine components, the engine oil and the transmission oil from overheating, they are cooled using coolant. A mechanical coolant pump circulates the coolant in the cooling circuit. The heat quantities introduced to the coolant are emitted to the ambient air again using a radiator. An electric fan assists the radiator output. The coolant in the B46 engine is mainly circulated via a mechanical coolant pump. Several engines are also equipped with an electrical overrun pump which maintains a trickle of coolant to the bearing seat cooling system of the exhaust turbocharger.

Special features of the B46 cooling system
  • Coolant-cooled exhaust turbocharger
  • Mechanical coolant pump
  • And electric coolant pump
  • Characteristic map thermostat

Due to the twin-scroll technology, the B46 engines are equipped with a steel manifold. 'Twin-scroll' means that the exhaust flows are routed via two separate channels to the exhaust turbocharger. The heat produced is absorbed by the coolant which is supplied via a coolant connection on the exhaust turbocharger. When the motor is not running, post-cooling of the exhaust turbocharger is possible with the assistance of an electric coolant pump. This prevents a build-up of heat in the area of the exhaust turbocharger.

Water pump / coolant pump
The coolant pump is a single unit also containing the thermostat. The coolant pump housing is made from the aluminium alloy ALSi9Cu3, the impeller and the thermostat cover are made of plastic. The DME controls the cooling circuit via a map-controlled thermostat.

Lifetime coolant
The coolant is not subject to a change interval, the factory coolant is designed for the entire service life of the engine. Work which requires an opening of the cooling circuit, coolant must be replaced as needed. The cooling system must only be filled with BMW-approved coolant. If the wrong coolant is used, damage to the coolant pumps, coolant hoses, radiators and cylinder head gasket may occur.

Turbocharger

P90143708_highRes by Ryephile, on Flickr

The exhaust turbocharger of the B46 engine is a twin-scroll exhaust turbocharger. To facilitate a fast and direct response, the exhaust flows from cylinders 1 and 4, and 2 and 3 are merged and routed to the compressor via two separate channels. This principle is referred to as pulse turbocharging. The exhaust manifold and exhaust turbocharger housing have been designed as one common cast part and cannot be replaced individually. The charging pressure in B46 engines is controlled via an electrically adjustable wastegate valve.

Blow-off valve
A blow-off valve is not used in current models. Pressure peaks, caused by sudden load shedding due to the inertia of the turbine of the exhaust turbocharger, can be avoided by careful tuning of the Digital Motor Electronics software. With foresighted charging pressure control, pressure peaks can be predicted and reduced by quick adjustment of the electrically-adjustable wastegate valve. Assisted by a delayed load control of the Valvetronic (in the minimum lift direction) or the throttle valve (in the closed direction), the remaining charge air which is produced can be routed to the exhaust emission system via the engine. This form of control thus prevents the exhaust turbocharger shaft from being exposed to excessive torsional stress due to high pressure peaks.

Wastegate rattle
Apparently BMW is fine with a little wastegate rattle at startup. They state if the wastegate valve is opened when cold, pulsation of the exhaust gas may cause vibrations in the wastegate valve, which are perceived as noise. This is not due to a defective component, and is normal running noise. This noise becomes less audible as the temperature of the component increases.

Fuel System

BMW B48 fuel system HPFP fuel rail by Ryephile, on Flickr

The main high pressure fuel pump (HPFP) is a single-piston high pressure pump by Bosch, similar in concept to the unit on the N20/N55. At this point BMW seems to have resolved all HPFP failures so there should be no concerns about that. The high pressure pump is driven by a triple cam which is attached to the exhaust camshaft. Fuel low pressure is supplied to the high pressure pump via the fuel feed from the in tank electric fuel pump.

The direct rail represents a departure from the familiar systems used up till now. With this system, the high pressure lines have been omitted and the injectors are attached to the rail directly.

Directly connecting the solenoid valve injectors to the rail has the following advantages:
  • Less volume needs to be available for high-pressure injection
  • Fewer interfaces and therefore less problematic with respect to leaks
  • Short cycle times during production due to compact design

BMW B46 engine - transmission side by Ryephile, on Flickr

BMW B46 engine - side view by Ryephile, on Flickr

BMW B46 engine - Belt view by Ryephile, on Flickr

Here are some extra pictures from BMW's B38/B48 press release event. This is a picture of the engine cutaway showing the piston crown and skirt. Note the broad piston crown "bowl", this is where the combustion flame kernel occurs. Also a picture of the Vavletronic servo and camshaft cutaway.

P90143710_highRes by Ryephile, on Flickr

P90143704_highRes by Ryephile, on Flickr

Cheers,
Ryan
 
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