Date:         Wed, 2 Oct 2002 02:48:21 EDT
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Re: On the Vanagon Cooling System
Comments: To: damoncampbellvw@YAHOO.COM
Content-Type: text/plain; charset="US-ASCII"

In a message dated 10/1/02 11:22:08 PM, damoncampbellvw@YAHOO.COM writes:

<< I do have a question about one of your main points, though, regarding that
of the radiator capacity.  I am certainly no automotive expert, but it seems
that when looking at the capacity of the radiator core, you'd wan't to look
more at the volume of liquid it is passing through it, rather than the
overall size... I can't imagine a radiator the size of a vanagon's with
coolant flowing through a single tube the size of a drinking straw would
corroborate your conclusion of being overcooled.  Or more subtly, a radiator
that was 671.34" deep by 1" high by 1" wide would not be a terribly effective
cooling device either.
To add more factors into your equation, is the torturous air path through the
vanagon's radiator taken into account?  Making a sharp 90 degree turn right
after the radiator is not the best way to keep CFM up... >>

Damon,

Actually the analysis is quite pragmatic and really summarizes the
characteristics of passenger car radiators. The analysis treats 2 tube
radiators with a 0.1 offset (add to factor) for a 3 tube unit and subtract
0.1 for a single tube unit. As to the airflow issues, I find a 0.5 inch (of
water) pressure differential between the front of the radiator and a point 10
inches behind. Compare this to only 0.2 inches for the equivalent dimensions
on the Chevy small block. Both numbers taken at 35 mph, no fan on. The
airflow into the typical American engine compartment is far more occluded
than the Vanagon. That turn is more like 50 degrees and the radius of the
turn is competitive with the mean diameter of the air wall cross-section.

To treat the problem more thoroughly, the surface area of the radiator should
be added as well as the free air aperture. But in the end the extended
coolant volume will compensate for these smaller effects.

Frank Grunthaner