Air Temp effects on Atomization????

[Steve.Flanagan at VerizonWireless.com]

Here is a question maybe some of you can shed some light on!

Last year we decided to convert our air/air intercooler to a water/air
intercooler simply by building an ice box around it.  Turbo application.  

We ran the car the week before, and it ran flawlessly with the air/air.
Intake air charge went from 120 deg F up to 265 deg F from start to end of
pass.

One week later we bolted the converted intercooler (water/air) on and ran
the car.  It seemed to buck a little and lay down as the car went down the
track.  Air charge now only went from 80 deg to 140 deg F from start to
finish line. We lost about 1-2 tenths in the 1/4 mile over the next few
passes, from 7.60 to 7.80  It slowed down.  Yes I was scratching my head. 

What do you think would cause the car not running correctly with the colder
air?  From all we saw, we came to general conclusion that at current fuel
pressure, with the colder air, the fuel was not atomizing efficiently.
These were all assumptions.

Does this make sense, is it harder to burn the same (pressure) of fuel in
colder air?  And would this require a harder spray to help the fuel to
atomize.  If this is the case, then what is the coldest you can get the air
charge up to before you run into problems.

I was running the old PV=nrT formula, and trying to understand the
difference between air charge of 130 deg down track vs 265.  Basically
before and after the change.  If you convert to Kelvin and look at a
constant Pressure, the Volume increases by about 20%.  I get 402 deg K vs
333 deg K at the same P, so 402/333 = 1.20, now wouldn't this 20% increase
in volume, provide for a 20% increase in CFM which should add a decent
amount of horsepower????

Now wouldn't the 20% increase in air volume also require a 20% increase in
fuel to prevent going lean?

With that in mind I am trying to determine the benefit of getting this air
charge down to below 100 deg.  But I am gun shy to lower the air charge
because of the above scenario.  

We still do not know why the colder air slowed the car down, but assume it
was from problems with atomization.  

Currently we raised the fuel pressure, dropped the map to maintain the same
amount of fuel as before and this year we have not had the problem.  But it
is in a new motor so its not an equal comparison.


Thanks

Steve  
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