[DeTomaso] Rear Window

Stephen steve at snclocks.com
Thu Mar 24 12:01:33 EDT 2016


I would say "Well Duhh", except, well, I would be saying it to myself.  Your
idea of mounting a box to the external grill and getting air flows is spot
on.  

Your question about mounting the fan to the external grill is another good
one.  I fear that the turbulence behind the car would pretty much trash any
readings from that side - if the anemomether had a cone on its inlet side it
would likely work better, but I suspect the cone would have to be stout to
handle the turbulence.

For a relative reading, where the monitoring fan is now is probably not bad.
But, I really like the idea of doing a static test to see what impact the
fan direction has on air flow.  Of course, then there is the issue that
pushing through the condenser (flow from inside to outside) will reduce the
area of the condenser that gets the most airflow.  But, given flows cut back
significantly as now designed, I don't see this as a biggie.

And, lastly, I agree, I suspect adding a rear window will increase pressure
on the back-side of the condenser.

Stephen Nelson



-----Original Message-----
From: Joseph F. Byrd, Jr. [mailto:byrdjf at embarqmail.com] 
Sent: Wednesday, March 23, 2016 8:32 PM
To: 'Stephen' <steve at snclocks.com>; 'Julian Kift' <julian_kift at hotmail.com>
Cc: detomaso at poca.com
Subject: RE: [DeTomaso] Rear Window

My thoughts are the sales info about pusher/puller efficiency does not
distinguish the use of shrouding.  Pushers for coolant radiators would not
have a full shroud since it would reduce frontal area for speed induced air
flow.  The use of a pusher tip diameter shroud does not provide air flow
through all the radiator area.  This does not mean that reversing the
rotation hurts the fan blades efficiency, for a curve or foil design blade
it will significantly.

You have the means to actually measure which provides more flow (at stand
still).  If you fabricate a "box" to fit the condenser exterior grill and
taper to use the anometer so it could measure the air flow in each
direction.

A suggestion/observation...do you think you would get a better
representation of condenser air flow if your computer fan was mounted on the
external grill?   

My guess is that when you add the rear window, you will increase the force
wanting to blow air out through the condesor

Joe

-----Original Message-----
From: DeTomaso [mailto:detomaso-bounces at poca.com] On Behalf Of Stephen
Sent: Wednesday, March 23, 2016 22:53 PM
To: 'Julian Kift'
Cc: detomaso at poca.com
Subject: Re: [DeTomaso] Rear Window

Pushers are fundamentally less efficient - apparently.  Jet indicates that
they are 80% as efficient as a puller.  But, heck, if the flow through the
condenser drops by 50% at speed, and in fact goes up if the flow is
reversed, would likely make up for such a loss of efficiency.

 

Thank you for your comments.

 

Stephen Nelson

 

 

From: Julian Kift [mailto:julian_kift at hotmail.com]
Sent: Wednesday, March 23, 2016 7:41 AM
To: Stephen <steve at snclocks.com>
Cc: detomaso at poca.com
Subject: Re: [DeTomaso] Rear Window

 

I reread my response and my apologies I was not clear in stating that the
stock setup is a sucker fan designed to pull external air through the
condenser into the engine bay, what you found at Jet is indeed a pusher.
Some fans are sold as reversible, but the Jet offering appears to have
straight blades and may significantly reduce efficiency wired as a puller.

 

Julian

  _____  

From: Stephen <steve at snclocks.com <mailto:steve at snclocks.com> >
Sent: Wednesday, March 23, 2016 6:56 AM
To: 'Julian Kift'
Cc: detomaso at poca.com <mailto:detomaso at poca.com>
Subject: RE: [DeTomaso] Rear Window 

 

Could you send a picture of your installation?

 

On fan directions - I guess I am confused - Jet indicates their fan is a 10
inch pusher.  Doesn't that mean it will push air through the radiator, not
suck it through?

 

 
<https://jet.com/product/detail/2aa79945005d4343a7ecd53e0cdd1409?gclid=CLKtu
Pnz1csCFUVhfgodUd8LVQ>
https://jet.com/product/detail/2aa79945005d4343a7ecd53e0cdd1409?gclid=CLKtuP
nz1csCFUVhfgodUd8LVQ

 

Stephen Nelson

 

 

 

-----Original Message-----
From: Julian Kift [mailto:julian_kift at hotmail.com]
Sent: Tuesday, March 22, 2016 9:07 PM
To: Stephen <steve at snclocks.com <mailto:steve at snclocks.com> >; 'Dave'
<davel at emspace.com <mailto:davel at emspace.com> >
Cc: detomaso at poca.com <mailto:detomaso at poca.com>
Subject: Re: [DeTomaso] Rear Window

 

But it's a sucker fan, pulling air into the rear compartment.

 

Larry stock carries a nice upgrade, it fits the stock 10" shroud diameter
perfectly after removing the three mounting tabs for the stock fan (I just
installed one last week) and rated at 950cfm.

 

Julian

 

________________________________________

From: DeTomaso < <mailto:detomaso-bounces at poca.com>
detomaso-bounces at poca.com> on behalf of Stephen <
<mailto:steve at snclocks.com> steve at snclocks.com>

Sent: Tuesday, March 22, 2016 8:54 PM

To: 'Dave'

Cc:  <mailto:detomaso at poca.com> detomaso at poca.com

Subject: Re: [DeTomaso] Rear Window

 

Hmmm - looks like a 10 inch opening in the original shroud, and Spal makes a
low-profile pusher -
<https://jet.com/product/detail/2aa79945005d4343a7ecd53e0cdd1409?gclid=CLKtu
P>
https://jet.com/product/detail/2aa79945005d4343a7ecd53e0cdd1409?gclid=CLKtuP

nz1csCFUVhfgodUd8LVQ  only 2.05 inches thick.  Hmmm.  650 CFM.  Only $58.

 

Stephen Nelson

 

 

 

-----Original Message-----

From: DeTomaso [ <mailto:detomaso-bounces at poca.com>
mailto:detomaso-bounces at poca.com] On Behalf Of Dave

Sent: Tuesday, March 22, 2016 7:42 PM

To:  <mailto:detomaso at poca.com> detomaso at poca.com

Subject: Re: [DeTomaso] Rear Window

 

Or reverse the leads and turn the impeller over.

(Ok - not helpful)

dave

 

 

On 3/22/2016 6:06 PM, Stephen wrote:

>     Hmmm - reverse the leads on the existing fan or move the condenser 
> to

>     the front of the car.  Hmmm...

> 

> 

>     The work I've done suggests reversing air flow would likely be 
> pretty

>     darned effective, especially at speed.  But, will have to wait for

>     summer to see if it really does make the a/c colder.

> 

> 

>     I also suspect it would be interesting to be cruising down the

> road

and

>     s/d the condenser fan - and see if the temperature at the a/c 
> vents

>     goes up, down or holds.  Absolutely, monitor the temperature - and

make

>     sure you don't over pressure your system (an increasing vent

>     temperature would be a pretty good warning).  But, it would give 
> one a

>     better idea of the impact of a sucker fan on the condenser.

> 

> 

>     Fortunately 5332 is still using R12 - I ended up with around 40 
> pounds

>     of it when the big switch hit.  So, plan to stay on it for all my

older

>     cars.  Less risk of hoses going out.

> 

> 

>     Stephen Nelson

> 

> 

>     [1]SNClocks.com

> 

>     Click here to join one of our mailing lists [2]Contact Lists

> 

>     Click here for our new [3]Hammered Dulcimers galleries

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>     Click here for [4]my new blog on finding happiness in retirement

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> 

>     From:  <mailto:jgkrenton at comcast.net> jgkrenton at comcast.net [
<mailto:jgkrenton at comcast.net> mailto:jgkrenton at comcast.net]

>     Sent: Tuesday, March 22, 2016 4:08 PM

>     To: Stephen < <mailto:steve at snclocks.com> steve at snclocks.com>

>     Cc: Jeff Detrich < <mailto:jjdetrich at gmail.com> 
> jjdetrich at gmail.com>;
<mailto:detomaso at poca.com> detomaso at poca.com

>     Subject: Re: [DeTomaso] Rear Window

> 

> 

>     You could always move the condenser to the front of the car like 
> many

>     have done.  I believe this modification is reported to be quite

>     effective.

> 

> 

>     Jeff Kimball/2467

> 

> 

> 

> 

> ______________________________________________________________________

> _

> 

>     From: "Stephen" <[5] <mailto:steve at snclocks.com> 
> steve at snclocks.com>

>     To: "Jeff Detrich" <[6] <mailto:jjdetrich at gmail.com>
jjdetrich at gmail.com>

>     Cc: [7] <mailto:detomaso at poca.com> detomaso at poca.com

>     Sent: Tuesday, March 22, 2016 12:54:02 PM

>     Subject: Re: [DeTomaso] Rear Window

> 

> 

>     You are right Jeff - especially because the fan powers from a wire 
> on

>     the dash-mounted temperature control that is separate from the 
> wire

>     that powers the a/c compressor clutch.

> 

> 

> 

> 

>     Stephen Nelson

> 

> 

> 

> 

>     SNClocks.com <[8] <http://www.snclocks.com/> 
> http://www.snclocks.com/>

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>     Click here for my new blog <[11] <http://www.perfectoldman.com/>
http://www.perfectoldman.com/>  on

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> 

>     From: Jeff Detrich [[12] <mailto:jjdetrich at gmail.com>
mailto:jjdetrich at gmail.com]

>     Sent: Tuesday, March 22, 2016 12:10 PM

>     To: Stephen <[13] <mailto:steve at snclocks.com> steve at snclocks.com>

>     Cc: [14] <mailto:detomaso at poca.com> detomaso at poca.com; [15]
<mailto:tjaarda at astranet.it> tjaarda at astranet.it

>     Subject: Re: [DeTomaso] Rear Window

> 

> 

> 

> 

> 

> 

>     On Tue, Mar 22, 2016 at 1:25 PM, Stephen <[16]
<mailto:steve at snclocks.com> steve at snclocks.com

>     < <mailto:steve at snclocks.com> mailto:steve at snclocks.com> > wrote:

> 

> 

>      The positive pressure under the rear of the car when it is moving 
> at

>        speed, coupled with the likely vacuum behind the car reduces 
> the

>        efficiency of the a/c condenser fan.  My tests suggest that 
> around

>     60

>        mph the air-flow through the condenser is reduced by about 40%.  
> At

>        around 80 mph it is reduced by over 50%.  While I don't have a

>     massive

>        amount of data, what I have suggests that the decrease in flow

>     through

>        the condenser is not directly proportional to car speed, and 
> that,

>     in

>        the 90 to 100 mph range the flow through the a/c condenser 
> drops to

>        around nothing.

> 

> 

>     Sounds like if you are going to be cruising at very high speeds, 
> just

>     having a kill switch on the condenser fans would be helpful. That

would

>     be easy to wire I would think.

> 

> 

> 

> 

>     Jeff

> 

> 

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