With all due respect let me offer these thoughts..
I looked at your numbers on your site and all seem to be spot on some of the
assumptions I do not agree with though. Two easy but not necessarily related
ones are on inter cooler sizing and effective compression ratios.
You can not mathematically as you suggest take the area required for
an inter cooler and fold it up into a cube it will not work especially
for air to air units. The reason being as the core gets thicker the
efficiency goes down. Thin large cores always out perform small thick
ones and generally by a large margin. The reason is the delta T that
each row in the core sees and the amount of air flow though the core
which goes down as thickness goes up. So as the core gets thicker it
does not get smaller as quickly as you might suggest. On the air to
water units the reasoning is very simple but they lose air flow
performance as they get thicker as well. So you need more boost to
overcome this. The reason you invert the working fluids is the Delta T
on the air side. As the air goes over the fins it is cooled. The first
row does the most work, but you still have 32 degree water in the next
row and air that is cooler going over it. So that extracts more BTUs
but far less than the first row. As you go through the core it is less
and less effective thermally and increases airflow restriction as
another loss. If the core is 4 or 5 inches thick it better have some
'loose' fins or it is a loser.
Effective compression ratio..For this to work it has to work in both
directions. Your example 25 lbs boost 8.5 CR= 22.9/1 CR Why does the
air fuel mix not auto ignite like a diesel? We have vaporized fuel
high pressure and very hot air.. For this to work three things have to
be true. 1. I can run gasoline in my diesel with no problems. 2. I
need an ignition system to make it start up. 3. There is an available
gasoline that will not auto ignite at 22.9/ CR.
It is posible to mathamatically play with this to prove the point but
it does not account for a few things. Those being CR is a volume issue
and geometric in nature. Turbo charging is mass flow related, we are
changing density not volume. We still have the same volume but denser
stuff. The final pressures involved are about the same, but I can not
see how the temperature rise would be the same as going from 8.5/1 and
25 lbs boost to 22.9/1 NA either as amount of compression to reach the
final pressure is vastly different. So the temperature rise can not be
the same. This makes the comparison not work in my mind. If you do the
temp calcs you will see what I am talking about. If you do them and
figure the increased pressure due to temperature rise I think you
might be amazed as to how high the pressure goes. I can tell you right
now I use fuels suitable for 15/1 CR for boost in the 35 lb range. VP
C-16 comes to mind right away..
Dave
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