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  #21  
Old February 8th 10, 05:38 PM posted to alt.autos.bmw
Dave Plowman (News)
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Posts: 1,533
Default Engines

In article >,
dizzy > wrote:
> That's my understanding of it. But with more cylinders you can rev
> higher, making for significantly more horsepower.


Not a consideration on road going cars. A four cylinder can rev way beyond
that. Straight sixes don't usually have a very high limit because of crank
twist. Hence the design not having been used in racing for many a year.

> Plus you get the
> smoothness and lose the flatulent, putter-putter, economy-car sound.


Go to the even more economy car sound then - like a three cylinder. ;-)

> I'll take the more cylinders.


> The inline-6 is a great engine design. Both my cars (323 and Supra)
> have an inline-6. Cool! 8)


> Hopefully consumer demand will compel BMW to continue to offer a good
> range of 6's in the 3-series.


I hope they do too. But in the smaller sizes - and remember in most of the
world they will be the big sellers - a forced induction 4 cylinder can
make more sense.

--
*I didn't fight my way to the top of the food chain to be a vegetarian.

Dave Plowman London SW
To e-mail, change noise into sound.
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  #22  
Old February 8th 10, 09:32 PM posted to alt.autos.bmw
Dean Dark[_2_]
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Posts: 126
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On Mon, 08 Feb 2010 16:38:18 +0000 (GMT), "Dave Plowman (News)"
> wrote:

>> I'll take the more cylinders.

>
>> The inline-6 is a great engine design. Both my cars (323 and Supra)
>> have an inline-6. Cool! 8)

>
>> Hopefully consumer demand will compel BMW to continue to offer a good
>> range of 6's in the 3-series.

>
>I hope they do too. But in the smaller sizes - and remember in most of the
>world they will be the big sellers - a forced induction 4 cylinder can
>make more sense.


I just loved the way the 1600 cc straight six in my old Triumph
Vitesse ran and sounded. It's a shame that the car was such a
bleeding rust bucket.
  #23  
Old February 8th 10, 09:51 PM posted to alt.autos.bmw
bfd
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Posts: 133
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On Feb 8, 8:38*am, "Dave Plowman (News)" > wrote:
> In article >,
> * *dizzy > wrote:
>
> > That's my understanding of it. *But with more cylinders you can rev
> > higher, making for significantly more horsepower.

>
> Not a consideration on road going cars. A four cylinder can rev way beyond
> that. Straight sixes don't usually have a very high limit because of crank
> twist. Hence the design not having been used in racing for many a year.
>
> > *Plus you get the
> > smoothness and lose the flatulent, putter-putter, economy-car sound.

>
> Go to the even more economy car sound then - like a three cylinder. ;-)
>
> > I'll take the more cylinders.
> > The inline-6 is a great engine design. *Both my cars (323 and Supra)
> > have an inline-6. *Cool! * 8)
> > Hopefully consumer demand will compel BMW to continue to offer a good
> > range of 6's in the 3-series.

>
> I hope they do too. But in the smaller sizes - and remember in most of the
> world they will be the big sellers - a forced induction 4 cylinder can
> make more sense.
>

The 2010 E92 320d turbo diesel puts out something like 177hp/259ft-lb
torque. 0-60 is supposedly in the mid-7 sec range getting something
like 36mpg....That's not too bad for a "4-banger." Good Luck!
  #24  
Old February 10th 10, 03:16 AM posted to alt.autos.bmw
dizzy
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Posts: 570
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David Skelton wrote:

>You do not necessarily need more cylinders to rev higher.


It sure helps - with more cylinders comes lighter components, shorter
strokes thus lower piston velocities, more area for valves*...
Although Dave' point about I6 being rev-limited by it's long
crankshaft has some validity...

*Note that all these things help the engine wear longer.

>But as revs rise, losses rise exponentially,


Why "exponentially"? Is it a squaring effect? Is it pumping losses
or mechanical friction that's the worst culprit? I don't suppose you
could provide an actual formula?

>wear rates rise and efficiency drops.


It seems they all have plenty of "wear resistance" these days, though.
I don't think engine wearing-out is what usually what brings the car's
life to an end...

>Horsepower is 'work done' and at higher revs more work is done giving more
>horse power.
>Usually, higher revving engines have a shorter stroke and thus lower torque
>values (area under the curve on the graph).


But you can gear them shorter, making-up for the slightly-less torque
(with that "wear penalty"). Torque is really dominated by
displacement, of course.

I wonder if these traditional "torque trade-offs" can be eliminated
with modern VVT technology (especially if lift is also variable)!

>I, too, prefer the smoothness of the straight six. Some 4 cylinder engines
>sound OK, but IMO, not the boxer 4 in the Subaru Impreza.
>I also like the low rev torque of forced induction diesel (428 ft-lbs at
>1750 rpm in our 335d :-))), but the diesel is not as smooth as the straight
>6 petrol.


I think a V4 in a car would be really cool - good balance (no need for
balance shafts if it's 90-degree), a better sound, fairly compact. Of
course, a V is more expensive, with twice the cams, etc, but not
ridiculously so - my motorcycle has a DOHC *twin*, and it's not an
expensive motorcycle.

  #25  
Old February 10th 10, 01:15 PM posted to alt.autos.bmw
David Skelton
external usenet poster
 
Posts: 58
Default Engines


"dizzy" > wrote in message
...
> David Skelton wrote:
>
>>You do not necessarily need more cylinders to rev higher.

>
> It sure helps - with more cylinders comes lighter components, shorter
> strokes thus lower piston velocities, more area for valves*...
> Although Dave' point about I6 being rev-limited by it's long
> crankshaft has some validity...
>
> *Note that all these things help the engine wear longer.
>
>>But as revs rise, losses rise exponentially,

>
> Why "exponentially"? Is it a squaring effect? Is it pumping losses
> or mechanical friction that's the worst culprit? I don't suppose you
> could provide an actual formula?
>
>>wear rates rise and efficiency drops.

>
> It seems they all have plenty of "wear resistance" these days, though.
> I don't think engine wearing-out is what usually what brings the car's
> life to an end...
>
>>Horsepower is 'work done' and at higher revs more work is done giving more
>>horse power.
>>Usually, higher revving engines have a shorter stroke and thus lower
>>torque
>>values (area under the curve on the graph).

>
> But you can gear them shorter, making-up for the slightly-less torque
> (with that "wear penalty"). Torque is really dominated by
> displacement, of course.
>
> I wonder if these traditional "torque trade-offs" can be eliminated
> with modern VVT technology (especially if lift is also variable)!
>
>>I, too, prefer the smoothness of the straight six. Some 4 cylinder engines
>>sound OK, but IMO, not the boxer 4 in the Subaru Impreza.
>>I also like the low rev torque of forced induction diesel (428 ft-lbs at
>>1750 rpm in our 335d :-))), but the diesel is not as smooth as the
>>straight
>>6 petrol.

>
> I think a V4 in a car would be really cool - good balance (no need for
> balance shafts if it's 90-degree), a better sound, fairly compact. Of
> course, a V is more expensive, with twice the cams, etc, but not
> ridiculously so - my motorcycle has a DOHC *twin*, and it's not an
> expensive motorcycle.
>


Your original post:
So... are the lovely BMW 6's going to be replaced by turbocharged
4-bangers? I'm sure the bigger/higher-end ones will still have the
turbo 6 or an 8, but the 3-series that most people buy, may be going
to 4. Lighter and more efficient, you know...


I was giving you reasons why that might happen.
Car companies are under pressure to reduce the impact of the car on the
environment. Therefore, it makes sense to design and build engines that use
less fuel.
You do not use less fuel by revving high.

I agree that lighter components can lead to higher revving engines which
will output more power. But this is at the cost of using more fuel.
Some single cylinder bike engines used to rev to 18,000 rpm.

Losses rising exponentially is non-linear, and both frictional and pumping
losses are partly to blame. It requires more and more energy to keep
increasing the velocity of a mass. Hence, to drive a pump at 20,000 rpm uses
more than twice the energy than it does to drive the same pump at 10,000
rpm. I'm sure that you knew this. An engine could be considered an air pump.

Many, many idiots thrash their engines from cold which does not help as the
oil cannot do its tasks completely until it is up to temperature. Also, if
one races around at full throttle at every chance (as some do), then the
engine will have a shorter life. As will the rest of the transmission. But
they can be replaced.

Lowering the gearing raises the revs which is not good for mpg.

Torque is determined by lots of factors, displacement being one of them.

Variable valve timing and lift is constantly being explored and improved. It
is now much better than it was 20 years ago.
Some BMW 4 bangers have no throttle butterfly, instead the engine speed is
controlled by valve lift. Those engines are called valvetronic, introduced
in around 2001. Here is a link:
http://www.usautoparts.net/bmw/techn...alvetronic.htm

We used to have some cars with V4 engines in the UK, but I have no
experience of them.

A lot of V engines on the market today have fewer main bearings than their
in-line counterparts. It is only my preference to have more bearings holding
the crank, especially when an engine produces a lot of torque. I could not
(many do) trust the 3.0 litre Mercedes-Benz V6 diesel engine producing 372
ft-lbs of torque that has only 4 main bearings, AND an aluminium crankshaft.

Motorcycle engines do not have the same requirements as car engines, so I do
not know what the relevence is.
If you put a 200 horsepower motorcycle engine in a 5 series, it would be
pathetic as they develop no low end torque.

Expensive ?? The expensive part is the design and testing of new engines.
Once the tooling is made, cost per unit reduces as more are made.

Best wishes

David




--- news://freenews.netfront.net/ - complaints: ---
  #26  
Old February 10th 10, 05:33 PM posted to alt.autos.bmw
Dave Plowman (News)
external usenet poster
 
Posts: 1,533
Default Engines

In article >,
David Skelton > wrote:
> So... are the lovely BMW 6's going to be replaced by turbocharged
> 4-bangers? I'm sure the bigger/higher-end ones will still have the
> turbo 6 or an 8, but the 3-series that most people buy, may be going
> to 4. Lighter and more efficient, you know...


Well, the new 5 Series will be available with a four cylinder in some
markets. As were the older ones. 3 Series too. But in the US they may try
to protect the 'exclusive' image (and prices) by not selling the more
basic versions.

--
*Young at heart -- slightly older in other places

Dave Plowman London SW
To e-mail, change noise into sound.
  #27  
Old February 10th 10, 07:55 PM posted to alt.autos.bmw
David Skelton
external usenet poster
 
Posts: 58
Default Engines


"Dave Plowman (News)" > wrote in message
...
> In article >,
>> So... are the lovely BMW 6's going to be replaced by turbocharged
>> 4-bangers? I'm sure the bigger/higher-end ones will still have the
>> turbo 6 or an 8, but the 3-series that most people buy, may be going
>> to 4. Lighter and more efficient, you know...

>
> Well, the new 5 Series will be available with a four cylinder in some
> markets. As were the older ones. 3 Series too. But in the US they may try
> to protect the 'exclusive' image (and prices) by not selling the more
> basic versions.
>
> --
> *Young at heart -- slightly older in other places
>
> Dave Plowman London SW
> To e-mail, change noise into sound.


Dave,

Just after ordering our 335d in July 2009, I looked at the US BMW site. The
US cars had quite different specs and options than those in the UK. Also, US
cars come with pre-paid servicing whereas we have to pay more, if it is
wanted, over here.
I think that Xenons were standard ( we had Xenons on two Audis, they were
not as good everyone said) as were other things that I cannot remember, but
the options list was smaller.

Best regards

David



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news://freenews.netfront.net/ - complaints: ---
  #28  
Old February 11th 10, 01:03 AM posted to alt.autos.bmw
Dave Plowman (News)
external usenet poster
 
Posts: 1,533
Default Engines

In article >,
David Skelton > wrote:
> > Well, the new 5 Series will be available with a four cylinder in some
> > markets. As were the older ones. 3 Series too. But in the US they may
> > try to protect the 'exclusive' image (and prices) by not selling the
> > more basic versions.


> Dave,


> Just after ordering our 335d in July 2009, I looked at the US BMW site.
> The US cars had quite different specs and options than those in the UK.
> Also, US cars come with pre-paid servicing whereas we have to pay more,
> if it is wanted, over here. I think that Xenons were standard ( we had
> Xenons on two Audis, they were not as good everyone said) as were other
> things that I cannot remember, but the options list was smaller.


I've also seen BMW diesels used as taxis in either Spain or Portugal - and
obviously made for that job, with imitation leather seats. In the UK it's
either cloth or real leather.

--
*Ah, I see the f**k-up fairy has visited us again

Dave Plowman London SW
To e-mail, change noise into sound.
  #29  
Old February 11th 10, 11:45 AM posted to alt.autos.bmw
David Skelton
external usenet poster
 
Posts: 58
Default Engines


"Dave Plowman (News)" > wrote in message
...
> In article >,
> David Skelton > wrote:
>> > Well, the new 5 Series will be available with a four cylinder in some
>> > markets. As were the older ones. 3 Series too. But in the US they may
>> > try to protect the 'exclusive' image (and prices) by not selling the
>> > more basic versions.

>
>> Dave,

>
>> Just after ordering our 335d in July 2009, I looked at the US BMW site.
>> The US cars had quite different specs and options than those in the UK.
>> Also, US cars come with pre-paid servicing whereas we have to pay more,
>> if it is wanted, over here. I think that Xenons were standard ( we had
>> Xenons on two Audis, they were not as good everyone said) as were other
>> things that I cannot remember, but the options list was smaller.

>
> I've also seen BMW diesels used as taxis in either Spain or Portugal - and
> obviously made for that job, with imitation leather seats. In the UK it's
> either cloth or real leather.
>
> --
> *Ah, I see the f**k-up fairy has visited us again
>
> Dave Plowman London SW
> To e-mail, change noise into sound.


I'm not so sure about the 'real' leather.
Someone from the far east whom says they make the 'leather' and that it is
not top layer hide, and sometimes it is pigskin.
Either way, it seems to have some sort of coating that prevents our skin
from breathing naturally. In the summer my back and legs get quite damp from
sweat, even through clothing. The trouble with not specifying 'leather' is
that it seems no-one will want the car second hand without leather. :-(

I had another quick look at the BMW US website, and the 335d has a different
engine output to that of ours in Europe, 265 hp in the US, 286 PS (282 hp)
in Europe.
They do not have the choice between an SE or MSport, and the cars do not
have an alarm as standard. But, they do get power seats and a 4 year
warranty, 4 years servicing and 4 years roadside assistance.
The cars are a bit cheaper too. About 20% ish. Grrrrrhhh... Even though we
managed to negotiate more than 12% discount, the US car specced nearly to
the same as ours, retails for £2,000 less than what we paid. , before any
haggling with the dealer.

Best wishes

David

(who is the f**k- up fairy ?)



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  #30  
Old February 11th 10, 12:01 PM posted to alt.autos.bmw
Dave Plowman (News)
external usenet poster
 
Posts: 1,533
Default Engines

In article >,
David Skelton > wrote:
> I'm not so sure about the 'real' leather. Someone from the far east whom
> says they make the 'leather' and that it is not top layer hide, and
> sometimes it is pigskin. Either way, it seems to have some sort of
> coating that prevents our skin from breathing naturally. In the summer
> my back and legs get quite damp from sweat, even through clothing. The
> trouble with not specifying 'leather' is that it seems no-one will want
> the car second hand without leather. :-(


Dunno what type of animal skin it is - but it does come from one or
another. And I think it has a coating of some form of clear lacquer, as
fluids don't sink in. Makes it very easy to clean.

--
*When companies ship Styrofoam, what do they pack it in? *

Dave Plowman London SW
To e-mail, change noise into sound.
 




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