Lighter Wheels and Radiators AD V7 #929

["C.M. Smith" <cmsmith@domain.elided>]

It's definitely worth pursuing lighter wheels and tires. I put a set of
cheapie Korean Alloys (and I do mean cheap!) on my mundane Mazda
(officially, it's my daily driver, the back up for the 164 in case parts
are hard to get sometimes, kids seem to drive it a lot though). What an
amazing difference from the steel wheels. The ride is much more compliant
and the handling crisper. Why such a difference? First, even cheap alloys
are significantly lighter than steel of the same size. Unsprung weight is
anathema to good handling and compliant ride. Second, alloy wheels are
significantly stiffer than steel. I remember my late lamented Datsun 510
with 155 section bias plies on it. Put a set of 165 (whoa baby!) steel
radials on it and the wheel covers used to creep in hard corners!!! (I'm
not kidding, with the windows open you could hear those puppies creaking as
the rims deflected). Now good steel wheels should be stiffer than that but
even good ones (read "heavy") can't match even cheap alloys. Good alloys
are unbeatable.

BTW, many street drivers do not realize that even light alloy is still
significantly heavier than tire sidewall, and tire tread is heavier than
tire sidewall. So, remember that when seized with the unbearable longing
for bigger wheels and wider lower profile tires, your handling and ride may
deteriorate unless you get pretty obsessive about calculating the relative
weights of your proposed wheel/tire combo.

I recommend against tinkering with any ducting or shrouding near a
radiator, as well as trying to allow more air into the engine compartment
around the radiator, rather than through it. Auto makers are very clear on
the drag penalties of radiators, only thing worse is air streaming into the
engine compartment with no streamlining. The air should ideally all be
deflected around the bodywork (ever wonder why Le Mans cars are so much
faster than F1 cars, less drag from the envelope body). But this would
cause drastic overheating at speed. Ford designed a very clever radiator
grille many years ago for their little Fiesta. At highway speeds the
spacing and shape of the horizontal grille bars caused the air gaps to
progressively close up aerodynamically, leading to consistent flows at any
speeds for cooling and minimizing drag from too much air entering the
engine compartment.

Shoot, want to get sophisticated, tilt the radiator forwards at the top and
put extractor grilles in the hood, then at least you'll be getting some
down force from the thermal pumping effect. How much faster did you say you
wanted to go?
Michael Smith
Calgary, Alberta
Canada
91 Alfa 164L, White, original owner 

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