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#21
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"Dave Plowman (News)" > wrote in message ... > In article >, > Malt_Hound > wrote: >> Which brings me to another thought... why do we need fans that run >> directly off the engine, increasing and decreasing with engine speed, >> when in all reality, the biggest need for additional air flow thru the >> radiator will be at the lowest engine speed, and the least need for the >> fan will be at higher rpm when we are making good speed? > >> Seems like an intelligently controlled electric fan would be a better >> design, no? > > Or a progressively driven mechanical one which idles when not needed... > The latest hi-tech zenith of efficiency is the Viscotronic fan. This has an engine management controlled variable speed viscous fan. It is an amazing piece of kit. I happen to have a bit of experience with an application where a diagnostic laptop can be linked to the vehicle and the speed of the fan can be infinitely varied within reason by means of mouse on slider. It so happens that I have two near identical vehicles except that one has a simple viscous coupled fan and the other having the latest viscotronic unit and the reduction of noise from the latter is very noticeable. With the same fan blades it is probable that this equates to a significant gaining of horsepower or reduction in fuel consumption. Huw |
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#22
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"Ross Garrett" > wrote in message ... > > "Jan Kalin" > wrote in message > ... >> In article >, Ross Garrett wrote: >>> >>>"Malt_Hound" > wrote in message ... >>> >>>> Which brings me to another thought... why do we need fans that run >>>> directly off the engine, increasing and decreasing with engine speed, >>>> when >>>> in all reality, the biggest need for additional air flow thru the >>>> radiator >>>> will be at the lowest engine speed, and the least need for the fan will >>>> be >>>> at higher rpm when we are making good speed? >>>> >>>> Seems like an intelligently controlled electric fan would be a better >>>> design, no? >>> >>>I am pretty certain the new era of BMW's have electric radiator fans. I >>>thought I read somewhere that is one of the means they used to lower >>>engine >>>loading to increase power yet maintain fuel efficiency (apparently better >>>battery capabilities mean less load without the fan belt, but also no >>>increased load for the alternator). The fan and fan speed are driven by >>>signals from the engine controller. I also think they might have electric >>>water pumps for the same reason. >>> >>>And I know both my E39's had at least some semblance of an electric fan >>>because it would run long after the engine shut down on hot days when the >>>AC >>>had been used. >> >> That's the auxillary electrical fan for cooling AC condenser. The main >> fan >> is mechanical with a viscous clutch. Check out >> http://www.realoem.com/bmw/partgrp.d...44&hg=11&fg=35 >> for the main fan (located between the radiator and engine) and >> http://www.realoem.com/bmw/partgrp.d...44&hg=64&fg=55 >> for the AC fan (located in front of the radiator). > > Thanks. I was wrong on the new cars' water pump too. The site clearly > shows the water pump and alternator run from the same belt. > Diesel versions have an extra electric water pump which continues to pump coolant around the turbocharger bearing and cylinder head area after shut-down. Huw |
#23
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"Dave Plowman (News)" > wrote in message ... > In article >, > Malt_Hound > wrote: > > Yeah, but my SAABs with 4 cylinder transverse engines all had electric > > fans, and they were pretty darn reliable. > > With a transverse engine and a front mounted rad it would be difficult to > have an engine driven fan... It would be difficult to have an engine driven fan that was between the engine and the radiator. If one didn't care where the fan was relative to where the radiator was, then it would be a relatively simple matter to have an engine driven fan. It wouldn't be a very useful fan though. |
#24
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In article >,
Jeff Strickland > wrote: > > With a transverse engine and a front mounted rad it would be difficult > > to have an engine driven fan... > It would be difficult to have an engine driven fan that was between the > engine and the radiator. Not so - the original Mini did just this. With a side mounted rad... > If one didn't care where the fan was relative > to where the radiator was, then it would be a relatively simple matter > to have an engine driven fan. It wouldn't be a very useful fan though. -- *A bartender is just a pharmacist with a limited inventory * Dave Plowman London SW To e-mail, change noise into sound. |
#25
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great, another thing that can go wrong and cause overheating -
an electric water pump. is it so much better than the aluminum one in the newer E36 ? >>and BMW is using an electric water pump (engine cooling, not just heater core flow) in the E90... |
#26
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Dave Plowman (News) wrote:
>> In article >, >> Malt_Hound > wrote: >>> Which brings me to another thought... why do we need fans that run >>> directly off the engine, increasing and decreasing with engine >>> speed, when in all reality, the biggest need for additional air >>> flow thru the radiator will be at the lowest engine speed, and the >>> least need for the fan will be at higher rpm when we are making >>> good speed? >> >>> Seems like an intelligently controlled electric fan would be a >>> better design, no? >> >> Or a progressively driven mechanical one which idles when not >> needed... err, but it DOES do just that..... |
#27
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In article >,
spare-me-spam > wrote: > >>> Seems like an intelligently controlled electric fan would be a > >>> better design, no? > >> > >> Or a progressively driven mechanical one which idles when not > >> needed... > err, but it DOES do just that..... ;-) -- *Those who live by the sword get shot by those who don't. Dave Plowman London SW To e-mail, change noise into sound. |
#28
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Huw wrote:
> The latest hi-tech zenith of efficiency is the Viscotronic fan. This has an > engine management controlled variable speed viscous fan. It is an amazing > piece of kit. I happen to have a bit of experience with an application where > a diagnostic laptop can be linked to the vehicle and the speed of the fan > can be infinitely varied within reason by means of mouse on slider. It so > happens that I have two near identical vehicles except that one has a simple > viscous coupled fan and the other having the latest viscotronic unit and the > reduction of noise from the latter is very noticeable. With the same fan > blades it is probable that this equates to a significant gaining of > horsepower or reduction in fuel consumption. Cool beans... That is the exact bit of trivial detail that had me asking the question in the first place. On my Z3, once the engine reaches full temperature, the fan noise at normal engine rpm (above 3000 rpm) is annoying, even though I'm tooling along at a high enough rate of speed so that the need for the fan is negligible. -Fred W PS - I'm just back from 2 weeks R&R in northern Maine, in case anyone missed me (or hoped I had dropped off the planet...) |
#29
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spare-me-spam wrote:
> Dave Plowman (News) wrote: > >>>In article >, >>> Malt_Hound > wrote: >>> >>>>Which brings me to another thought... why do we need fans that run >>>>directly off the engine, increasing and decreasing with engine >>>>speed, when in all reality, the biggest need for additional air >>>>flow thru the radiator will be at the lowest engine speed, and the >>>>least need for the fan will be at higher rpm when we are making >>>>good speed? >>> >>>>Seems like an intelligently controlled electric fan would be a >>>>better design, no? >>> >>>Or a progressively driven mechanical one which idles when not >>>needed... > > > err, but it DOES do just that..... > > No, it doesn't. The fan runs even when the car is moving forward at a high speed forcing more air through the radiator than the fan ever could. -Fred W |
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