Choice of radiators.

Originally the article on radiators about heat conductivity, core, fin design, tube sizes and design changes with all latest
market findings and trends become a thesis but then I realized it was fairly irrelevant or of no use to most Mini owners who only have a few options or requirements.

Original Brass/Copper or Aluminum.
If you enter any of the following in google you can update yourself on technology
Aluminum Versus Copper Brass radiators What makes the better radiator-Aluminum or Copper/brass radiators
Cuprobraze based on the CuNiSnP system (latest radiator technology)
  For the mini owner you are stuck with the original side mounted 10.5” to 11” square radiator from 1959-to 1996, or front mounted as per the MPI.


  So lets make life easy—for originality, fit the Copper fins on brass tubes type radiators always painted black to stop corrosion.
If you have an original embossed Coventry Radiator’s top tank or MK1 with the top hose outlet at the end of the top tank-try getting it re-cored. For the MK2 they
moved the top hose outletin about 1.5” to help reinforce it from breakage/cracking through vibration especially via the old hoses when they became rigid.

There is a lot of criteria to take into account as to which is the best or worse radiator as the mini has seen so many changes in
radiator caps and thermostats- First thermostats were mainly 74c known for summer use, 82c for winter use which then became all year use on all A plus engines,
then 88 degrees centigrade from 1990 on to make the engine thermally efficient---
 
The first radiators used a 7lb cap with a 33.6mm long spring neck which was replaced by the current size of about 27.5mm long.
Some Cooper cars had 10lb and then 13lb became the standard until 1990’s when Rover fitted a15lb radiator cap plus an electric fan as standard on 1275cc engines.
I would always recommend fitting an electric fan to any Mini which might run hot at any time, as you do not want your engine running to hot or to cool. Never fit an
oil cooler to a road car without an oil thermostat for the same reason.
Higher the pressure cap poundage, the hotter the coolant has to get to boil.

A 15lb cap fitted as standard from 1990 is sufficient as Engines normally work best and more thermally efficient at 180-210 Fahrenheit
owing to enforced pollution laws, oil and petrol now available. Having too much pressure in the system can result in damage and to little can cause overheating.

Remember anti freeze makes the engine run hotter!
Mini values have increased so dramatically many owners only want to keep their cherished possession in an original standard condition
without an electronic fan which is usually fine on standard engines especially 850/998cc. My standard rebuilt Cooper S Mk3 has a 2 core with original header tank
and it runs to cool in winter and only gets to correct temperature on really hot days with normal driving. All engines run different
   

Copper fins on brass Tubes as original.

For standard engines ARP2000 and GRD172 are sufficient with the later only being different in that it has the twist in sender unit facility
for 1275 cars with electronic fans from 1991 on.  Both these radiators have 3 offset rows of thin tubes where manufacturers found out thin tubes broke the
coolant down into smaller amounts which further improved cooling by lighter material and heat transfer.

ARP2000

GRD172

Always try to fit an electric fan if you feel that your car runs to hot in the summer.   I have been watching radiator designs all my Mini life
as most of my tuned cars with high compression ratios overheated, especially my 970cc “S” and 8 port engines.
Most modern day cars have an engine coolant temperature of around 90 degrees with the engine oil temperature similar or well above and with the
specialist oils they are able to run on much lower oil pressures unlike the mini which absorbs power and lowers BHP-so beware-running your engine to cool causes
piston and crank bearing wear.

In 1978 mini Spares introduced

C-ARA4444

The 4 core which has 4 rows of offset tubes and 12% larger fluid capacity which was the best radiator
available until 1991 when the 2 core with 2 inline rows of tubes was produced.   This radiator has the superior cooling V shape fins but can clog up in certain
conditions such as Grass track or autocross racing whereas the flat finned 4 core does not and can be cleaned by hose easier. Therefore the 4 core still has its place
in Minis such as the Clubman where there is a greater area for air to move around or hot climates where greater water capacity is required when using
overflow/expansion tanks.

The 2 core c-ARA4442 still remains the mini owners favourite for tuned and race engines albeit in 2014 we found a close contender-ARP1106 with 3 inline
rows of tubes and V type fins which seems slighter better on some engines by holding radiator pressure on tick over or when the engine is switched off which
Historic racers require when changing drivers. ARP1106 is slightly cheaper but has no drain plug or screw in sender facility although any future demands might
change design but that will cost us £10.50 +vat. Extra.

C-ARA4442

ARP-1106

The brass 2 core is very intricate with the largest brass tube sizes possible without loosing strength or increasing weight without much gain in cooling.
 

Aluminum-Bright and beautiful

If you are not worried about keeping your Mini original looking and want a lightweight/ bright looking or super cooling radiator then aluminum
is the answer. The C-ARA5000 is the lightest radiator with V shape fins and 2 rows of inline tubes with about 25-30% more cooling area than the standard cores of
ARP2000/GRD172 type. It has 10% better cooling than a 4 core when racing.

C-ARA5000

Copper fins have about 70% more heat conductivity than the aluminum fins but the copper type have solder that the brass tubes require which acts as
a thermal barrier, but the all brazed aluminum with larger tubes cool much better.

Mini Spares C-ARA5000 with a13lb rad cap was designed after seeing the original ugly ill-fitting cheap imports from China with 8 lug nuts welded
on the side for the cowling.  These fabricated alloy radiators started life by somebody as a copy of our original 2 core radiator.  Mini Spares gave the design to
a UK company who then set about getting the top tank smaller and sides as original to fit the radiator cowlings properly. The last part was to put a drain plug
with same thread to accept our screw in sensor and position the bottom hose outlet in the correct position to fit the early Coopers plus all other minis
similar to all our radiators.

As stated before –make sure your engine runs warm enough for both oil and water temperatures but if nothing else has suited your cooling then we have
C-ARH4441 with a huge single tube 42x3mm tube size and the core is fully vacuum brazed for durability with V section fins and is the best off the
shelf UK made radiator available.  Even this was not enough for our Mini Sprint with 1460cc and 8 port fuel injection but they were able to make an off the shelf
68mm thick core special and coupled with an overflow tank this done the trick.

C-ARA4441

When changing to an alloy radiator always ensure every part of cooling system is drained down and thoroughly cleansed as they are more prone to
suffer from galvanic corrosion. Galvanic corrosion can occur with any electrical faults such as your choke cable becoming your earth wire owing to bad battery
connection or early positive earth cars causing any engine and coolant metals to react.  Modern cars are designed for aluminum parts, reducing the risk of galvanic
corrosion so when fitting aluminum radiators or other parts to classic minis with cast iron blocks always check electrics, flush and change antifreeze regularly as
instructed with ethylene glycol, a 1/3^rd mix is good down to -19c and a 50/50 mix as now often recommended  by manufacturers which helps break down
contaminates with its chemical additives and is good down to -36c. USE DISTILLED WATER only.

Reducing anti freeze levels in summer will help cooling as it absorbs heat about half as much as water.  Aluminum radiators usually last longer in
cars designed for them than Copper brass types so regular maintenance is required in Minis.
Importation rules regarding vehicles are very specific: Only those over 25 years in age may be brought in to the USA without compilance to Federal Motor Vehicle Safety Standards (FMVSS).