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RE: Aluminium radiators

To: <mgb-v8@autox.team.net>
Subject: RE: Aluminium radiators
From: "James Nazarian" <jhn3@uakron.edu>
Date: Wed, 21 Sep 2005 18:52:34 -0400
In-reply-to: <000801c5beca$62ddc720$f97f9e18@carlfloy>
Reply-to: "James Nazarian" <jhn3@uakron.edu>
Sender: owner-mgb-v8@autox.team.net
Thread-index: AcW+zKkgXRZG9LfiRLqXZgjO6bdTpwAKiAKg
I don't mean to sound confrontational but in the interest of preventing the
spread of mis-information...

A couple of basic truths:

Aluminum has roughly twice the convective heat transfer coefficient as
brass.
Air has roughly 1/100th the convective heat transfer coefficient as
aluminum.
This means the problem is getting the heat out of the metal into the flowing
air not out of the coolant into the rad.
Construction techniques do effect conduction heat exchange but the biggest
concern is from rad to air.
All fans work better when ducted.
All radiators work better when sealed to the intake of the car (thus forcing
the air to go through them and not around).
A puller is more efficient at cooling than an identical airflow pusher.
The closer the blades are to the rad and/or duct the better.
Any fan blade can be poorly designed and inefficient.
Any electric motor can be poorly designed and inefficient.
Group a couple of these things together and your car won't cool.
Avoid them and it will (to the best of it's capacity).

The more of these things you do right the less airflow you need.

If you want anecdotal evidence consider that no FWD car has a mechanical
fan.
Many modern RWD cars don't have mechanical fans.
Sure the engines are more efficient, but so is airflow management.
Stock RBB electric fans are notoriously unreliable and inefficient.

The radiator I use to cool my V8 is a $100 stock replacement for the 1.8L VW
Scirocco, the fans are a $175 summit racing special designed to seal to that
radiator.  The radiator is virtually sealed to the body.  The
advantage/disadvantage is that this is a very low, very wide setup that
requires significant modification to install in exchange for a very
favorable layout that I wanted.

James Nazarian
71 MGBGT V8
71 MGB Tourer
87 BMW 325es

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