>         In Brazil tried to cool the fuel, and it gave (they said)
>         improved
> efficiency. heheh ;o)

Cooling fuel does give more efficiency but not directly. It's quite
common for race cars to run a "cool can" which is a bucket of ice
that the fuel line runs through. A small increase in efficiency is
gained by the atomized fuel cooling the intake air, making it more
dense so it improves the volumetric efficiency. It's worth a couple of
horsepower, which isn't much but it is cheap.

The major gain occurs when it gets into the combustion chamber
and cools the residual gases from the previous exhaust cycle.
Removing some of that heat means that you can run a higher
compression ratio and that makes more power. Water injection
does the same thing.

It's similar to Octane ratings. A higher octane doesn't produce
more power, but it allows you increase the peak cylinder pressure
(through static compression ratio, supercharging, etc) before
unwanted things occur. That assumes no EFI computer that winds
it up until it starts to rattle and then backs it off half a turn.

> Thats what I thought nitros oxide did, help cool the fuel air mixture
> so ya can get more in there, as with turbo charging supercharging etc.

Nitrous is really good at cooling the intake temp as it is in liquid
form until it is right in the intake stream. Crack open a propane
tank and see how cold the valve gets. Then it does a double duty
by using up combustion chamber heat to dissociate into nitrogen &
oxygen. And then as an added bonus, you've got twice as much
free oxygen to burn.
Because of the cooling you can bolt 150hp of nitrous onto a V8
without any modification other than retarding the timing a bit
(notwithstanding the bottom end hanging together). If you did the
same with a mechanical supercharger, you'd be draining pistons
out of the sump plug.

> I always asked why not just add a bottle of O2 but that is obvious
> now.

It's been tried but it has a few major problems. A tank the size of a
scuba bottle holds around 90 cubic feet of gas under pressure. A
street 350 cid engine sucks around 600 cubic feet of air per minute
so a tank isn't going to last long.
Second problem - Pure oxygen + oil = bang. This is good if the
bang occurs in the right place and at the right time. You've just got
to get it there.
That's what makes nitrous so good, it needs the heat of the
chamber to break into a form that goes bang and is relatively inert
until then.

More power !
:-)

Steve.


======================================================
Steve Baldwin                Electronic Product Design
TLA Microsystems Ltd         Microcontroller Specialists
PO Box 15-680, New Lynn      http://www.tla.co.nz
Auckland, New Zealand        ph  +64 9 820-2221
email: steveb@tla.co.nz      fax +64 9 820-1929
======================================================

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