BMW 520

[Suxelis]

Interesting that theory doesn't always hold up in practice....examples? The smoothness of the new 159 4-pot and the Lexus V6's; both cases the top of their game.

[Yang62]

test drove the 520 recently. actually, not that bad. just a little bit slower than the old 520i with the 170hp 2.2l I-6.

 

however, at 166.8k, its not really a good deal. You CAN get it at 160k flat if you lend it for a couple of days to PML for their sponsorship of some event here in singapore (similar to the APEC deal...). However, there are a lot of other specs missing compared to the 523i, like a crappier aircon, no auto-folding mirrors, and uglier interior trim (plastic instead of wood). Given that 523i is at 173k plus, would you really go for the 520i?

[Astrid]

Q1. I assume you mean F8/F6 = H8/H6 = boxer on Porsche/Subaru. If that's the case, why are there so few manufacturers adopting this sort of engine? ... even supercar makers.

 

Q2. Dont BMW use balancer shaft to reduce/cut down vibration?

 

Q1: I don't think (am not aware) of any manufacturer still making Flat-8 (F8) engines anymore.

Porsche used to, but only for their track-only racing cars. But not anymore now. Today, Porsche goes strictly F6.

 

I guess the reason is that although Boxer engines are short (and can be mounted lower), they are also very much wider than most engines. Think of it as a 180-degree V-engine and you will get the picture.

 

Putting a F8 engine into the engine bay, together with today's electronics, ECU boxes, ABS blocks yaada yaada, and it will be very very tight.

 

In addition, to balance-tune an F4 engine is so difficult. I have seen Alfa Romeo mechanics tune my Alfa 33 Boxer engine, using a liquid filled manometer (U-tube) and all. Tuning a F8 will require a lot of expertise, and is not something any workshop can do.

 

Even current Porche's F6 engine continue to be situated behind, allowing certain other engine support systems to be mounted in front.

 

Engine accessibility (for servicing and repair) is also something manufacturers consider when evaluating an F4 or F6 engine. Since is normally situated low-down, mechanics will need to remove a lot more equipment above it, just to gain access to the engine below ... even for a simple spark plug change.

 

Susceptibility to floods, an age-old Alfa problem, since the spark plugs are so low down, compared to in-line engines. As long as waters rise above the wheel axle layer, the boxer engine will likely die, earlier, first - before any in-line engine.

 

Thus considering all the pluses and the minuses, it is to no surprise that the F4/F6 engine is not much favored.

 

BTW, unlike the Alfa (or perhaps even Subaru), Porche engines at the back are not mounted in a horizontal position. This thus gives better accessibility and also situates the spark plugs much higher and the rest of 'em.

 

Q2: Why BMW don't use counter-rotating balancer shafts (CRBS) for their IL-6 engines? Because there is no need to!!! Even V6 engines (Lexus included) use CRBS to smooth out the imperfect V6 firing pattern. For IL-6, there is no need to, since each TDC (Top Dead Center) phase is exactly 120 degrees leading/lagging in-front-of and behind the next in BOTH the horizontal and vertical planes. In simple English, the IL-6 is able to attain 100% perfect balance, without the need of CRBS and the additional weight, rotating mass and frictional retardation that the latter introduces to the engine.

 

It is about science and art perfected into a single entity!

Hail IL-6!

Edited January 15, 2008 by Astrid

[Miles]

seems like the valvetronic 4 pot is the engine to avoid huh?

whether its in the 3 or 5.

 

no wonder my friend's wife replaced her 3 with a Nissan... saying nissan has less vibration than her bimmer.

[W210k]

Q1. I assume you mean F8/F6 = H8/H6 = boxer on Porsche/Subaru. If that's the case, why are there so few manufacturers adopting this sort of engine? ... even supercar makers.

 

Q2. Dont BMW use balancer shaft to reduce/cut down vibration?

 

Hi Miles,

 

Well, I think Porker and Astrid are more than qualified in helping me answer your questions, so I shall leave it at that.

Edited January 15, 2008 by W210k

[Akula]

Nah, was jus starting a thread on the " return " of this model/capacity car. Not a fan of BMW as of now, though never know maybe in the future. ( NO offense to the Blue n White propeller fans ). Can Confirm the engine is rated at 156BHP or 170BHP?

[W210k]

seems like the valvetronic 4 pot is the engine to avoid huh?

whether its in the 3 or 5.

 

no wonder my friend's wife replaced her 3 with a Nissan... saying nissan has less vibration than her bimmer.

 

Compared to BMW's current VANOS + Valvetronic implementation / know-how, IMHO, to-date, Honda's 3-stage i-VTEC and Toyota's VVTi-L are much better engineered implentations of combined cam phasing and valve lift timing technology.

 

(I am still uncomfortable on having electric stepper motors to turn cams that control valve lift duration).

 

The torque gap / flat spot experienced by the Japanese technologies at lower-RPMs have been mitigated somewhat (I think) by Honda's 3-stage i-VTEC technology. And I believe Toyota has also got that sorted out ... can't remember the name though (Valve-something, or Something-valve). Both don't use independent electric motors to do the trick, so they (still) remain in the same time-domain as the engine's rotating crank and cam shafts. That is very important (IMHO), from the engineering stand point.

Edited January 15, 2008 by W210k

[inlinesix]

vanos + Valvetronic is difference from i-vtec. Wif valvetronic, it remove d need 4 throttle butterfly in inlet valve. By removing throttle butterfly, it will reduce pump loss during low RPM. It is basically 2 improve emission during start-up.

 

Toyota's is called Valvematic.

 

Honda i-vtec is difference. It has a few variance. 4 SOHC I-vtec, it is basically valve lift + valve timing on intake valve. However, it does not remove throttle butterfly. I think A-Vtec is similar 2 both systems.

[Azarael]

thanks porker and the rest of the guys for explaining all the technology behind in line 6 and V6 and in line 4 engines...

 

u guys can put most car salesmen out of a job with your expert knowledge....i bet if i ask any PML sales exec, she/he will give me the blank look....

 

looks like i will be sticking to in-line 6 and V6 cars in the future ! once u tried a Il-6 or V6, very hard to be tempted by a four pot !

 

looks like i got to save up for the next generation 5 series or buy a old 335i in few years time.

[Carcraze]

Only limited units i think.

 

But totally not worth it. Top up a few k and get the 523i.

[Cmwmsoh]

looks like i will be sticking to in-line 6 and V6 cars in the future ! once u tried a Il-6 or V6, very hard to be tempted by a four pot !

Once you try a turbo, very hard to go back to NA.

[Ahbengdriver]

Hi jus noticed that PML brought in the 520i again. Understand its a 4 cylinder 2 litre ( 1995 cc ) engine similar to the current one in 320i but with direct injection! Think the BHP is 170 with torque of 210NM. Similar to the previous 520i but that was a 2.2 in line 6. List price in Carbuyer is about $168K. Any one have any other info to add.....? Err anti BMW 4 pots/badge also welcome....

 

I would give it a serious consideration. 170bhp/210nm is quite good from a 2L 4 cylinder. The torque especially should be sufficient to pull the car, which weighs about 1.8 tonnes?

[Akula]

Dun think its that heavy, kerb weight should be abt 1.6 tonnes, maybe 1.65t..... 1.8tonnes is in 7 series category.

[W210k]

Hehe ... once you tried IL-6 or V6 RWD, don't think you'll ever want to go back to FWD in any engine configuration!

 

Only way 'up' is to go AWD - aka Quattro, X-Drive, 4-Motion etc.

[Qr25vet]

Hi jus noticed that PML brought in the 520i again. Understand its a 4 cylinder 2 litre ( 1995 cc ) engine similar to the current one in 320i but with direct injection! Think the BHP is 170 with torque of 210NM. Similar to the previous 520i but that was a 2.2 in line 6. List price in Carbuyer is about $168K. Any one have any other info to add.....? Err anti BMW 4 pots/badge also welcome....

this engine is a failure in design itself...only merit i can see from this car is that its basic which means lesser problems...

[Qr25vet]

Only limited units i think.

 

But totally not worth it. Top up a few k and get the 523i.

i'da rather u get the 525I as the engines the same...only the DME is detuned....y pay 2.5L roadtax when u get only 2.3L's worth of power??

Edited January 29, 2008 by Qr25vet

[Qr25vet]

520i 4 cyclinder, it's a joke.

but businesses as businesses go, will bring anything back as long as it sells.

Just like how Ducati downsized the Monster 900 to 400....

 

BMW is losing to no one, it's the number selling car brand in town.

The day they become common like toyotas would be the day they die.

 

For $168k, not point.

 

I sell you my 3 yr old 525i for $125k

 

is that the one with the M54 engine??

[Qr25vet]

Hmmm... Valvetronic + Direct Injection

 

Adding 2 more layers of computer-managed timing functions associated with the Otto cycle, with the help of stepper motors on valve positioning.

Definitely something I personally would stay away from, re longer-term vibrational stability - until tested OTR, for at least one engine model's life time.

 

Will stick to my M52B25 engine, albeit 2.5L.

 

The idea of having a stepper motor (something you'd find in a dot-matrix printer)operating in a very hot engine compartment, sequencing valve open/close timing, does not sound good to me.

 

BMW has had problems with their early V8 Valvetronic engines especially (can be got from BMW USA's own website), since this further requires a pair of such stepper motors to work in sync, to ensure that the left and right bank valves both work in tandem. Having 2 electric motors to work in sync, in the order of milliseconds' accuracy is very challenging indeed. You can get them sync'd when new, but depending on how the electro-magnetic flux of the armature coils deteriorate with wear/tear and time, they can still go out-of-sync with time. All you need is say a 1 or 2 milli-second of valve opening (or closing) retardation on a bank of cylinders that will lead to measurable vibrations.

 

I have nothing against 4-pot BMW engines, though much prefer the IL-sixes for inherent stability. For 4-pot, need to replace engine mounts and do a major retune the block at least every 60,000 km ... otherwise the car's vibrations will not be insignificant. Even a 2L 16v Jap car of the same vintage will feel much smoother on idle, IMHO.

 

I'm guessing that you're driving an X3 from your avatar...and X3s Dont use the M52TU engine at all...its been M54 all the while....