More hot air

[graham.hilder@domain.elided (Graham Hilder)]

On the question of how much HP difference might be expected in a standard =
Alfa motor, when changing from hot under-bonnet air intake to cooler =
outside air, thanks Rich for your reply, advising that the HP figures came =
from a simulation written for a 2 litre motor, rather than from a test as =
such
 =20
Without wanting to sound overly doubtful, again I feel the need to ponder =
whether the order of improvement shown by these figures might be achieved =
in practice.  Going from 114 to 129 HP is a 13 per cent increase, which =
does seem an awful lot for so little effort..... very nearly a completely =
free lunch, and there aren't too many of those around.=20

I take Rich's point about the drop in power in carburetted aeroplanes when =
the carb heat is selected..... in fact I think that de-selecting carb heat =
may be one of the standard pre-takeoff checks in such planes, for ensuring =
max power (not that I'm a pliot at all, by the way). =20

So the power change does happen; that can't be demied; but the question =
for me though is still how much? I'd love to get 13 per cent or even half =
that for a two dollar length of cold air trunking and half an hour's work =
on the Alfetta or the GTV, but it seems too good to be true. And I'm =
pretty sure that in practice I didn't get that from fixing the inlet flaps =
and restoring the cold rammed air into our Alfasud inlets as the designer =
intended. Still, one of my plans for this winter's intermarque track =
series which we run in is to do some comparative tests with our two =
identical Suds racing against each other, one with hot non-rammed air and =
the other with the proper cold rammed air inlet. Those two cars (and we =
two as drivers) are so evenly matched on track that I guess a 10 per cent =
change would show up. This track series by the way is a dual sprint =
series, meaning that the cars race in pairs rather than in full grids and =
hence direct one-to-one car comparisons are easy to make without  =
interference from other cars or any safety compromise.  An excellent =
testing ground for those of us without dynos or the funds to hire out a =
track!

Regards to all,
Graham Hilder,
N.Z.
(Alfasud, GTV, Alfetta GTV)

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End of alfa-digest V7 #880
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