Understanding the difference between Diesel and Petrol Nitrous Oxide Injection
Diesels can use Nitrous Oxide
to supplement their power too. But there are some
important differences in the
To begin with you
cannot inject diesel fuel and Nitrous Oxide into the intake system or ports as
you would inject both fuel and Nitrous in a petrol engine.
The reason is simple, the
fuel ignites under the compression stroke and does so far
too early in the cycle -- way before it should! This means your engine
will either stop dead in its tracks or more likely break something expensive! Either way
wouldn't want to try it!
The fuel and nitrous
ignites due to the heat of compression rather than at the correct point when the
diesel injector fires. Normally there is just air in the cylinder, and the
ignition only commences at the correct time as the diesel
pump injects the fuel via an injector straight into the cylinder. The Diesel pump effectively controls
the timing in the same way as the spark does for a petrol
Adding Diesel fuel the the
intake tract is a sure way to drive over your crankshaft. Adding just
Nitrous without extra fuel just wastes the nitrous since there isn't any extra
fuel available for it to Oxidize / burn. So it just gets thrown out of the
exhaust. Doing this in a petrol engine would cause a weak mixture. Doing
this in a diesel engine does not.
Diesels ALWAYS run "weak" so to speak since
they always induct a full cylinder full of air as there's no throttle plate!
Even at idle. Speed is controlled purely by the amount of fuel injected. They
don't actually "run" weak as such, since the fuel enters via the injector at a
single point and it always rich at the point of injection since its not evenly
spread around the combustion chamber.
So at idle, and at less than full throttle operation much of the air travels
through the engine unused. and unburned. At full power all the oxygen and all
the fuel is consumed if the diesel pump is set up correctly. So if the
diesel is set up any richer on purpose it just smokes. Because now all the air
is used up, so the extra fuel goes out of the exhaust unburned. Now what
happens if we add more oxygen (or rather Nitrous Oxide) while it runs rich and
sooty? That's right, clean exhaust again and more power.
So to add extra
enrichment fuel to a diesel you need to do one of several
a) You add a fuel to the air intake that
ignite under the heat of compression alone. This can be done
with the normal solenoids and nozzle arrangement as you
would do in a petrol engine. The difference is that you
would use Propane gas instead of Diesel. Now the propane is
high octane and has a high self ignition temperature. It
will not ignite early, it will only be ignited by the burning
diesel fuel as it is injected at the correct timing point.
b) You do as above
with Methanol. Theoretically. Not tried by me so far! I suspect that it
will need to be injected very well atomised by the Nitrous fogger as close to
the cylinder head as possible to prevent it condensating or "dropping out" of
c) You fool or
trick your vehicles existing diesel injection pump into
delivering the extra fuel. There are a multitude of ways to
do this as there are so many different diesel injection systems around. So
that part will be up to you! Only do it when you activate the system.
Don't forget that
if you add a lot of nitrous you still need to retard the
timing as you do with a petrol engine via the injection pump timing.
Unlike a petrol
engine running "weak" does not bother a diesel engine. So
adding masses of nitrous with no extra fuel wont do damage.
All that happens is that the diesel injected burns away and
leaves the rest of the oxygen wasted and dumped through the
And running rich
with far too much fuel being added either with nitrous or
without results in lots of black exhaust smoke as this
diesel cannot be burned (soot!) as there was insufficient
So set it up to
show traces of black smoke so that you know you are burning
as much of the expensive nitrous as possible!