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BMW History and Engine Technology

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#30 of 67 Re: BMW 2.5 V6 [shipo] by circlew Mar 26, 2007 (3:36 am)
Replying to: shipo (Mar 25, 2007 11:21 am) In my humble opinion it is very precient that BMW is still using the I6.   I agree...simple is better. If you look to F1 racing, 4 tubes are the baseline.   I wonder why that has not filtered into the mainstream? I just can not imagine any reason 300 HP can not be achieved with 4 cylinders.   Regards, OW Replies to this message: shipo (Mar 26, 2007 7:03 pm) circlew (Mar 27, 2007 4:13 am)
#31 of 67 Re: BMW 2.5 V6 [shipo] by bruceomega Mar 26, 2007 (5:04 am)
Replying to: shipo (Mar 25, 2007 11:32 am) shipo,   Is the aluminum block with steel sleeves stronger than the magnesium/aluminum/silicone composite block? Was wondering if that is why BMW uses it for the turbo engine.   Is the aluminum block with steel sleeves also heavier? The 535i weighs a bit more, and is more nose heavy than the 528i.   Thanks Bruce Replies to this message: shipo (Mar 26, 2007 7:25 pm) brightness04 (Mar 26, 2007 9:11 pm) bruceomega (Mar 28, 2007 12:22 pm)
#32 of 67 Re: By the way... [brightness04] by fedlawman Mar 26, 2007 (6:47 am)
Replying to: brightness04 (Mar 25, 2007 9:12 pm) "When output are comparable, the lighter cars have significant advantage."   As you have already mentioned, there are minimum weight requirements for each class. Cars that are below minimum must add ballast. Replies to this message: brightness04 (Mar 26, 2007 12:39 pm) fedlawman (Mar 26, 2007 6:24 pm)
#33 of 67 Re: By the way... [fedlawman] by brightness04 Mar 26, 2007 (12:39 pm)
Replying to: fedlawman (Mar 26, 2007 6:47 am) Like you said, both E30 and E36 M3's are B stock. I'm not aware of any stock category cars need to add ballast for races in the same category. BTW, for races that involve different stock categories, the most frequent form of penalty points at this competition level involve time penalty not adding ballast. Stock cars don't have a good place to affix ballast. If not fixed down, ballast can be dangerous in fast turns. Replies to this message: fedlawman (Mar 26, 2007 6:24 pm)
#34 of 67 Re: By the way... [brightness04] by fedlawman Mar 26, 2007 (6:24 pm)
Replying to: brightness04 (Mar 26, 2007 12:39 pm) "both E30 and E36 M3's are B stock"   As are the Honda S2000 and a few Porsche 911's and 944's. The S2000 weighs the same as an E30 M3 and stock, has 40 more horsepower.   I know the stock and modified classes all have different rules, but believe me, it's more than just light weight that allows the older-tech cars to be competitive in their respective classes.   "If not fixed down, ballast can be dangerous in fast turns."   My wife said to tell you that's not funny...
#35 of 67 Re: BMW 2.5 V6 [shipo] by pearl Mar 26, 2007 (6:52 pm)
Replying to: shipo (Mar 24, 2007 12:17 pm) Shipo, you are correct of course that BMW has built I6 engines of greater than 3.0L. That said, I believe that with the demise of the 3.2L "M" engine (replaced by a V8), BMW will not have any sixes larger than 3.0L(correct???). I have read that BMW engineers do not like to make sixes with cylinder volume greater than .5L, so the current 3.0L engine variations may be it. If that were not the case, it would seem that simply punching out the 3.0L engines to 3.5L (or whatever) would have been much cheaper and simpler than designing a twin turbo engine with all the potential negatives (heat, etc) that come with turbocharging. Obviously, I don't know for sure, but short of a sea change in the BMW engine department, I bet we don't see any sixes bigger than 3L from here on out.
#36 of 67 Re: BMW 2.5 V6 [circlew] by shipo Mar 26, 2007 (7:03 pm)
Replying to: circlew (Mar 26, 2007 3:36 am) "I agree...simple is better. If you look to F1 racing, 4 tubes are the baseline.    I wonder why that has not filtered into the mainstream? I just can not imagine any reason 300 HP can not be achieved with 4 cylinders."   Four banger engines. Bleck!   Like V6 engines, with enough wizz-bang wingie-wingie balance shafts spinning twice the engine speed, you can counteract some of the natural imbalances of a four-cylinder engine, however, there is one force that cannot be counteracted. And what would that be? Torque reversals. A four-stroke engine requires a five cylinders (also naturally imbalanced, just less so than when compared to an I4 or a V6) before torque reversals (almost) become a thing of the past. Consider the following points:   1) Every combustion stroke provides meaningful acceleration of the crankshaft for approximately 140 degrees of rotation (approximately between 20 degrees ATDC and 20 degrees BBDC) 2) On a four cylinder engine, when any given cylinder goes "BANG" (more like wooosh actually), that piston will push the crank for about 140 degrees, followed by... what? Answer: 40 degrees of the crank pushing the engine through its rotational phases. Then another "BANG". 3) For every 360 degree rotation of the crank on a four-cylinder engine, the pistons are only turning the crank for 280 degrees. Hmmmm. 4) On a five-cylinder engine, a combustion stroke begins every 144 degrees of rotation, and as such, given the waxing of power on the newest cylinder to have its plug fire and the waning of power on the cylinder before it, torque reversals are almost eliminated. 5) On a six cylinder engine, a combustion stroke begins every 120 degrees of rotation, and easily overlaps the cylinder before it, thus completely eliminating torque reversal.   Can a four-pot engine generate over 300 HP? Yup, piece of cake. Heck, the old 1980s vintage 2.2 liter turbocharged four-cylinder engine from Chrysler was stressed to over 400 HP. I guess it's not too surprising that as a result of the robustness of that mill, there's been any number of aftermarket goodies released to the market to allow that engine to achieve the 300+ HP threshold with relative ease.   Best Regards, Shipo Replies to this message: circlew (Mar 27, 2007 4:13 am)
#37 of 67 Re: BMW 2.5 V6 [brightness04] by shipo Mar 26, 2007 (7:19 pm)
Replying to: brightness04 (Mar 25, 2007 9:01 pm) "Do you remember the current M3?"   M3 3.2 liter engines. Okay, fair enough. That said, I was intending to refer to only the mass-produced 3 and 5 Series engines, not the more hand built factory specials.   "As to smoothness, you'd be hard pressed to find fault in the Acura 3.5 or the Toyota 3.5 in terms of their smoothness."   No doubt that they are smooth enough to live with on a day to day basis, however, if I recall correctly, the balance shafts that they use to tame those beasties only cancel out the average vibrations brought about by the natural imbalances of the V6, and said canceling only completely occurs at one optimal RPM. As the engine RPM moves away from that point, the balance shafts do a poorer and poorer job of, ummmm, errr, balancing.   For my money, gimme an engine that is always in balance; regardless of load and regardless of RPM. That leaves me with an I6, an H6, a V8 (not technically true as all V8s are a little bit out of balance), or a V12.   Best Regards, Shipo Replies to this message: brightness04 (Mar 26, 2007 9:03 pm) habitat1 (Mar 27, 2007 2:33 am)
#38 of 67 Re: BMW 2.5 V6 [bruceomega] by shipo Mar 26, 2007 (7:25 pm)
Replying to: bruceomega (Mar 26, 2007 5:04 am) "Is the aluminum block with steel sleeves stronger than the magnesium/aluminum/silicone composite block? Was wondering if that is why BMW uses it for the turbo engine."   While I would be inclined to think that the composite block would indeed be stronger than the steel sleeved aluminum block, BMW seems to think otherwise. I gotta defer to them.   "Is the aluminum block with steel sleeves also heavier? The 535i weighs a bit more, and is more nose heavy than the 528i."   The block in the twin turbo mill is almost certainly heavier than the composite block in the 528i, however, not all of the weight gain between the two cars is due to the engine block. Consider the extra plumbing and intercoolers and turbos and coolant capacity for starters. Then consider the fact that BMW has a history of doing things like fitting larger and heavier brakes to up-engined models, and you can easily account for the weight gain without even digging any deeper.   Best Regards, Shipo Replies to this message: brightness04 (Mar 26, 2007 9:11 pm) bruceomega (Mar 28, 2007 12:22 pm)
#39 of 67 Re: BMW 2.5 V6 [shipo] by brightness04 Mar 26, 2007 (9:03 pm)
Replying to: shipo (Mar 26, 2007 7:19 pm) The 3.2 M3 engine is the only high output engine (i.e. not a long stroke engine designed for torque) with more than 3 liter that ever got put into the 3 series, which happens to be BMW's core business. It has to resort to iron block for packaging reasons, as an aluminum block would have been too long to fit into the car, and still leave enough passenger/trunk volume plus crumple zones. That's the point that I have been making.   The big advance in isolating/reducig engine vibration felt in the cabin was actually fluid enigne mount. Nowadays, some more advanced engine mounts are piezo-electric, counteracting engine vibration with signal from piston position sensors that have been put there to allow engine computers work anywhere. Regardless the virtues of V6 vs. I6 in the vibration department, Lexus achieved completely vibration-free cabin and steering long before BMW did; BMW is only catching up in that regard with the latest E90. V6's have a huge advantage over I-6 in packaging. That's why virtually every major carmaker has made the switch, with BMW as the lone exception. Aside from BMW, nowadays I-6 only finds new application in FWD transaxles (where the engine can be mounted horizontally) and trucks (where torque, hence engie stroke not bore, is the primary concern, and there's oodls of vehicle length to play with); otherwise, longitudinal I-6 runs into severe length/bore size limitation.   It's not like V6 came before I-6. All 6-cyl engines were I-6 until some smart-alec came up with the V idea to shorten the engine block length.

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