Sender: <marv@lancaironline.net> (Marvin Kaye)
To: flyrotary
Date: Fri, 18 Oct 2002 19:33:55 -0400
Message-ID: <redirect-1831905@logan.com>
From: peon@pacific.net.au
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Subject: Re: [FlyRotary] Heat Exchanger Efficiency was Re: EWP Tech Data
Reply-to: leon@promotorsport.com.au
Priority: normal
In-reply-to: <list-1831775@logan.com>

Hey Marv, Ken,  et al,

Cooling is firstly a function of the heat exchanger's ability to reject 
the heat transfered from the engine,  and a function of the specific 
heat of the coolant mediums.

If you have an efficient heat exchanger,  then cooling is NOT a 
problem. (Cooling a 1000 BHP blown ski boat V8 with river water is 
a breeze with a teenzy weenzy little stainless steel water to water 
heat exchanger.  

The principle is easily demonstrated by spraying a garden hose on 
a rad core and see how quickly the temp drops!!  All to do with the 
specific heat of water compared to the specific heat of air!!  Guess 
why they squirt water on intercoolers at full boost??

See,  if the heat exchanger is marginal for the power output of the 
engine (ever notice how 350 Chevvy V8s have bigger radiators than 
2 l Honda 4s?),  then there is most likely to be a cooling issue on 
hot days.

Years ago,  I figured out that a Mazda has about the same power 
as an early Chevvy V8,  (that's why the little suckers go so hard!!),  
so it needs a cooling system of about the same size. 

PowerSport initially had their radiator in a funny position,  and 
airflow through it,  to be kind,  was not optimal.  HIM at that "other 
place" has pointed this out as well on several occasions,  and HIM 
IS a good aerodynamicist.  You can have a humungous radiator,  
but if the air (or the water) can't get through it,  it just won't work.

Current thinking on rads in cars is to have a downflow rad (top to 
bottom) with and many passages as possible,  with as great a 
surface area as possible.  I'd be inclined to think that PowerSport's 
new radiator was a more efficient heat exchanger rather than the 
increased flow of the pump itself.  And maybe they rectified the air 
flow problems that HIM mentioned.

Leon Promet

On 18 Oct 2002, at 18:51, Marvin Kaye wrote:

> Posted for kenpowell@alltel.net:
> Hi Ed, Todd, Rusty, Leon, and List,
>        First of all, I want everyone to know that I really want Todd's
>        testing 
> to be 
> successful - this would solve a lot of problems for me.  I have been
> on record as doubtful of the ability of any EWP to flow enough coolant
> at a reasonalble amp level but you guys are making me wonder if some
> of our assumptions are wrong/incomplete.  But I am also a pragmatist -
> maybe some of our prior assumptions are wrong.  Thanks to Todd and
> Leon we will soon know the true skinny on this subject. 
>        Just as another bench mark, Powersport shared some of their
> instrumented data for us.  Their cooling system with a stock waterpump
> flowing thru a crossflow radiator at 35 GPM and they had trouble
> cooling their 215 HP above 90 degrees at a max rate climb (sound
> familiar).  They changed over to a standard radiator (straight
> flow???) and the flow rate went up to 57 GPH (can anyone verify my
> memory here) - note that their cooling problems went away.  They can
> now cool 215 HP in a max rate climb for a RV-6 on a 100 degree day. 
> Pretty impressive to me! 
> 
> Ken Powell 
> 
> 
> >  As Leon points out the 80 lit/min flow is equivalent to approx 25
> >  US gallons/min. The only 
> > figure I recall seeing on theMazda(if memory serves me correctly)
> > coolant is approx 13 GPM flow. If that is the case, then thedata on
> > the EWP indicates it will have no problem meeting the flow needs of
> > the rotary. .
> 
> >>  Homepage:  http://www.flyrotary.com/