NITROMETHANE
NOW that we are considering the use of Nitromethane it
may be as well to get one well held idea out of the way before we go any further
. . . that is that more power and therefore more performance can be obtained
by simply adding more Nitromethane to the fuel tank. Nothing could be further
from the truth, friends!
In actual fact this is perhaps one of the quickest ways of running into serious
mechanical trouble.
The actual name Nitro in itself to most people sounds explosive and at once
the idea of using this fuel leads the imagination to think of it getting into
the cylinder head end then being exploded by the spark, thus producing a violent
explosion in the engine, the extra power then doing more work and so giving
the extra performance.
The introduction of more Nitro-methane to the fuel is not just that of the addition until enough power is obtained, but rather that of well controlled amounts used in relation to the other factors.
CHART 2
Recommended jet diameter increases (guide only) for Nitro - methane / Methanol fuel mixes over those used for straight Methanol fuel.
|
% Nitro in Methanol |
Jet diameter |
|
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% |
1.0 1.12 1.22 1.32 1.41 1.5 1.58 1.66 1.73 1.8 1.87 |
Chart 2 indicates the increase in jet size to allow the increased amount
of fuel to flow as the ratio of Nitromethane to fuel is increased.
These figures in all cases provide a mixture on the rich side since as previously
pointed out, these fuels are relatively insensitive to mixture ratio compared
to petrol, and the consequences of running weak mixtures with these fuels
is likely to be more serious than with petrol since the power level will be
so much higher, also the thermal stresses.
Note how with 40 per cent nitromethane mixture the jet size has increased
by 1.41, or put another way by 40 per cent on the diameter, which as mentioned
before means an actual fuel flow of twice the original amount, so by comparison
with petrol we now have four times as much fuel required by the engine.
At 80 per cent mixture the fuel flow rate has be-come three times the rate
and therefore six times greater than petrol, hence the need to check the fuel
pump and fuel lines to make quite certain they can cope with this requirement.
DANGERS
Now, as before, it is necessary to know the dangers involved with the use
of nitromethane mixtures so
that the necessary precautions can be taken and understood, reducing them
to a degree that makes the use of such fuels acceptable under the circumstances
in which we normally operate.
Provided you know the dangers you can work with these fuels and come to no
harm, but if you do not, then it is possible through lack of simple precautions
to suffer, so bear them in mind at all times.
After combustion, mixtures containing nitromethane exhaust relatively large
amounts of nitric acid in vapor form, making the use of a proper gas mask
essential by the driver, and for those close to the car in the start area.
The reason for this is that nitric acid, when inhaled, causes a muscular reaction
making it impossible to breathe.
Little imagination is required to see the dangers involved with this possible
event taking place, and in fact there have been cases of drivers becoming
almost unconscious due to the bad fitting of face masks.
FIRESUITS
The mandatory use of fire suits adds to the generally held view that with
nitro-methane mixtures the fire risk is increased, but this is not so.
If you care to test this you can do so as follows. Take a small amount of
petrol, about one teaspoonful say, and place in a small tin lid and then ignite.
It will catch fire almost with a bang.
Now take the same amount of methanol and after the tin has cooled down, repeat
the exercise observing the almost lazy manner in which it ignites, burning
with a blue colour, the edges of the flame lined in places in yellow and orange.
Now take the same amount of nitro-methane, 98 per cent if you like, and repeat
the experiment and see how difficult it is to ignite, burning with a green
tinted flame in a reluctant manner.
This is due of course to the respective flash points of the three fuels, petrol
being the lowest at between zero and 40 degrees F. approximately, methanol
at 67 Degrees F., and nitromethane at 110 degrees F.
In other words with petrol you have a major fire risk and far less so with
nitromethane mixtures.
The real problem with nitromethane is its ability to release high power, especially
when ignited in a confined space.
Associated with this is its liability to be affected by shock.
Dropping a can of nitromethane will not cause an explosion, as the can, due
to its construction of light weight material, will not have sufficient rigidity,
but an amount in a very solid thick-walled container may.
EXPLOSION
There are three main possible causes of nitromethane becoming shock sensitive
and they are as follows:
The use of hydrazine as an additive, which, be it noted, is barred by regulations
in the USA for that very reason.
The use of caustic soda or any other alkaline, used for cleaning out a tank
or fuel lines.
Alloy tanks, which before anodizing, have been cleaned with such a substance
and have retained a small deposit.
To avoid any such possible troubles the tank must be filled with water and
10 per cent vinegar, plus a little ordinary household washing-up liquid, and
left to soak for several days.
One final note of warning concerning burning nitromethane and methanol is
that they can burn almost unseen in daylight, and you may well have a carburetor
or injector ignited by a backfire without appreciating the danger.
