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Re: [Amps] LK 500 ZA heat

To: "Tom Osborne" <>, <>
Subject: Re: [Amps] LK 500 ZA heat
From: "Roger" <>
Date: Mon, 13 Aug 2007 22:41:55 -0400
List-post: <>

> What was the original question?

Whether to suck or blow.

>> intake fan that is directing cool air at them.  OK, so you notice that a
>> fan in your computer is in the power supply and in the exhaust path.  It
>> is there because it is the cheapest place, not because it works best.

Those old computers had low wattage power supplies that didn't take a lot of 
cooling either.
Check the newer and higher powered computers. I have 5 and all have the fan 
on the INPUT side of the PS, not the output. They are also 140 mm, low RPM, 
nice and quiet fans.

>> The fan on your CPU blows onto the CPU and the fan on your video card
>> blows onto the video chip.

>> BTW, the reason your fan is electric is because most engines are
>> transverse mounted in front wheel drive vehicles and because it is
>> cheaper.

They were using the same set up well before the front wheel drive was 
common, but  an electric fan and control is a fraction of the cost of the 
old mechanical clutch they used for a while. The electric motor is also a 
whale of a lot more reliable. Another reason is that mechanical fan running 
all the time takes substantial energy to run at cruise speed. Also a fan 
that isn't turning fast enough as one at high way crusing offeres more 
drag/restriction to the air flow than does one with the blades stopped. This 
was one of the things they did to try and raise fuel efficency.

BTW I have seen set ups that had the fan drive shaft  run through a hole 
the center of the radiator. I don't remember what they were on and that was 
quite a few years back.


Roger (K8RI)
>> 73, Tim, W2UI
>> jeremy-ca wrote:
>>> Tom, you are so predictable. When you cant come up with a real answer 
>>> you
>>> resort to personal attacks.
>>> I dont know when the last time you lifted the hood in a car but
>>> horsepower
>>> robbing engine driven fans have been out of favor for around 25 years.
>>> The
>>> choice of all manufacturers is an electric pulling fan. This also holds
>>> for
>>> 500-800 hp and higher street rods with big V8's stuffed in very
>>> restrictive
>>> spaces. The Internet is full of studies of the comparisons between push
>>> and
>>> pull cooling.
>>> The air flow analogy is valid no matter the platform.
>>> Carl
>>> KM1H
>>> ----- Original Message ----- 
>>> From: "Tom Rauch" <>
>>> To: "jeremy-ca" <>; "dave arruzza" <>;
>>> <>
>>> Sent: Monday, August 13, 2007 3:28 PM
>>> Subject: Re: [Amps] LK 500 ZA heat
>>>>>> If you pressurize the inlet of a fan or blower, it greatly
>>>>>> increases outlet pressure. If you draw on the outlet it
>>>>>> hardly changes airflow. The inlet fan largely sets the
>>>>>> volume of air. The same is true for restrictions. If you
>>>>>> restrict an inlet, there is a huge air volume change. If you
>>>>> Tell that to the millions of car owners with electric fans that pull
>>>>> the
>>>>> air thru the restrictive radiator. Tests have long proven that trying
>>>>> to
>>>>> push the air thru the radiator is a bad idea.
>>>> Carl,
>>>> It's just silly to drag in unrelated arguments against something that 
>>>> is
>>>> a
>>>> clearly known fact, especially something so easy to prove with minimal
>>>> research or experimentation.
>>>> Cars suck air through the radiator because that's where the drive 
>>>> system
>>>> is. They aren't about to extend a shaft through the middle of the
>>>> radiator, so they burn up some extra horsepower with a less efficienct
>>>> air
>>>> system. Also the movement of the car through the air is what does 90% 
>>>> of
>>>> the air movement, the only real thing the fan does is cool the system
>>>> when
>>>> the vehicle is stopped or at slow speed. That's also when BTU's
>>>> generated
>>>> by the engine is less, since the fuel volume being burned is lowest.
>>>> Analogies to a 200 horsepower engine in a system that is not pressure 
>>>> or
>>>> noise critical and can't put the fan in the optimum place is a
>>>> tremendious
>>>> waste of time.
>>>>> Placing a small fan in exhaust mode has also saved many sweep tube 
>>>>> rigs
>>>>> from premature tube failure. Ask anyone who used Drake C Line in
>>>>> contests
>>>>> for example.
>>>> Anything is better than nothing Carl. He was talking about adding a fan
>>>> to
>>>> a system that already has a fan, not a convection system like the 
>>>> Drake.
>>>> This was just another lame meaningless analogy.
>>>> It is an undisputable fact air movers act like I outlined, and 
>>>> something
>>>> everyone designing or modifying a cooling system should know. Even
>>>> someone
>>>> working on a car.
>>>> 73 Tom
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