[Vwdiesel] Diesel vanagon A/C

Mon Aug 30 10:03:58 EDT 2004

Has anyone on the list used www.evanscooling.com in their diesels? There
are few Ford Powerstroke users that have made the switch. Just a thought
to addressing cooling issues. Here is an email from the Early Bronco
Mailing List from guy that works for Ron Davis Radiator. It is mostly
about fans but there is some information about loads and radiators.

Troy

A few random things I've learned about fans after being in the business
a little while:

Low-profile fans have their bearings very close together, so imbalance
or wind gust leverage at the fan edge has a larger effect on bearing
life. They also have printed circuit-looking armatures, and when the
bearings start to go just a little bad, the armatures hit the stator and
they short quickly. Remember that the bearings take a beating mainly
when the fan freewheels at highway speeds. Not that they're junk or
anything, just another consideration. The pancake fans also generally
have less CFM. Don't everybody start citing catalog data, this is a
generalization. 

Big quality differences between fans. I used to run the old Haydens
years ago, and they were only good for about a year in AZ. Now, there
are fans that will last for many years. The good fans have really good
seals and are balanced to a higher degree. Low voltage is what really
shortens life. We rarely replace fans, but when we do, it's almost
always due to low voltage at the fans. Always use a 30A relay for each
fan and direct wire the relays to the battery with big gage wire. 

A trick way lots of our customers wire their fans is to add two bosses
into the inlet side of the rad for temp switches, and run a 180 on one
fan and a 195 on the other. If the fan shroud has a dividing wall
between the fan chambers, you can run the fans independently. One comes
on regularly, and the other comes on when you really need it. Rad has to
be grounded, of course, for this to work, unless you run two pole
switches. 

CFM ratings by the manufacturers can't always be trusted. We recently
built a CFM test rig and the advertised numbers are often way off. Also,
again, generally speaking only-  the larger amp draw fans will have a
bit more power. Some just eat power because they're inefficient. In
other words, maybe two fans make the same CFM in an open wind tunnel,
but one may pull more air (vacuum) through a dense radiator core.
Granted, some are more efficient than others and this rule may be off,
but just something we've noticed. Good fan data will cite CFM vs. "delta
p" values which is the pressure drop between the two sides of the fan.
I've seen guys use the "business card test."  They'll drop a business
card in front of the rad and they consider the fans OK if it sucks the
card against the core. I pefer to stand behind the car and feel the
breeze... ;-)

The off-road racers we service almost always ask for SPAL fans. They are
made in Italy.  They pull big amps and are the best ones we've found
when you add power and reliability together. Might be more powerful ones
out there, but these rarely fail. Lots of good fans out there, but for
some reason, SPAL's are very prevalent in the pro off-road circles. Road
racers prefer other brands, since SPAL's pull a lot of amps. Really
well-balanced fans. 

Never mount your electric fan with the ny-tie things that go thru the
core. They will sand through the tubes in no time. 

Curved blades are for noise reduction- not greater airflow. The catalogs
will say different, but it's not what we've seen. They are just much
quieter.

We cool big engines, 500+ cubes and 1500+ HP with two 1710 CFM 14"
SPALs. Sounds impressive, but the idea is that for the street, you
aren't using 1500 hp for any length of time. Blowers and turbos add
heat, but nothing that can't be cooled with two big fans. Conversely, we
cool big engine drag cars with tiny 1 row, 1.25 tube rads with 15 x 16"
cores. The idea is the same, but with electric pumps, you cool on the
return pass when you're using 30 hp and in the staging lanes when it's
off and the fans and electric pump do their thing. They don't heat soak
much in 2 burnouts and a 10 sec run, so the little rads and fans can
delay overheating long enough and save weight and voltage. 

The hard part about cooling Broncos with stock sized rads is the load is
greater at low speeds, especially with AT's, so heat comes up more. If
you increase rad size, no sweat running two good 14" fans. Also, the
vertical engine bay traps heat and lowers rad delta p. Vent your hood.
Try running without your hood some time- you'll be amazed at how well it
stays cool. Winches and KC lights hamper airflow. At highway speeds, air
gets kicked up by the front axle and causes a high pressure area inside
the engine bay, lowering rad delta p, or more accurately, not letting
delta p rise to what the engine needs at highway speeds. Don't all rush
out and make air dams for your EB's now, you'll get pulled over by the
fashion police. However, a couple well-engineered air guides between the
grille and core support could funnel more air into the rad at speed,
offsetting the enginebay back-pressure. Air management is a technique
few even consider. 

Sealing your mechanical shroud is VERY important. Use foam tape. Air
takes the path of least resistance, and those 1/2" cracks are a lot
easier than the trip thru the core. Space the fan with it's edge halfway
into the shroud. You don't want the air getting centrifugally thrown off
the ends of the blades until it leaves the low pressure side of the
shroud. Ducted fans are always more efficient, even electrics. A ducted
cage or ringed bladeset is better than a star shape with no duct on
electrics. 

Doug Schulz
saguaro6 at cox.net

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Early Bronco Mailing List (EBML)

-----Original Message-----
From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com]
On Behalf Of Libbybapa at wmconnect.com
Sent: Saturday, August 28, 2004 9:33 AM
To: vwdiesel at vwfans.com
Subject: [Vwdiesel] Diesel vanagon A/C

I've been anticipating getting my '83 vanagon diesel on the road.  Stock

motor is being replaced with a 1.6 TD.  On the timing belt guard on the
old engine 
is the warning "This vehicles cooling system is not designed to
accomodate 
the added load of A/C" (quoted from memory, probably not word for word).
Any 
suggestions for increasing the cooling capacity to accomodate A/C?  I
live in 
Flagstaff which is ideal weather (7000 ft.), but am surrounded by
desert-almost 
unbearable April-Oct without A/C.  Any recommended additional oil
coolers? Non diesel content:  While reading up on the function of the
A/C system it 
popped into my head that the camper has a refrigerator that runs off of
propane. 
 My understanding is that it uses the heat from the propane flame to
boil 
another substance (ammonia? long time since I read up on the propane 
refrigerators) to use the pressure to push the main refrigerant through
the lines.  My 
question is why is the engine used to run a compressor (robbing hp and
economy, 
and increasingneccessity for cooling when it's hottest out) instead of
the 
waste heat from the exhaust?  The only explanations I see are that the
exhaust is 
not hot enough, or the system would be initially more expensive.  How
about a 
small stirling compressor run off exhaust heat?
Fun fact: 60% of energy used in the lower altitudes in the southwest is
used 
for cooling!!  30-40 years ago the first actively solar cooled houses
were 
constructed on the same concept as the propane refrigerator.  Solar
cooling 
proved more effective than solar heating, because as the need increased
so did the 
energy source. 60%?!!!
Andrew
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