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Why its jetted @ Solenoids
Why we cant use Oxygen!
V8 into Ford Sierra!
How to prepare your engine for Nitrous Oxide Injection use.
Engine Preparation for
OK, so for small doses of nitrous and
small power increases on road cars, we
don't really need any special preparation...
But... (Isn't there ALWAYS a
but!) There are a few very important things that you COULD
and SHOULD do if
you care about your motor and your success with Nitrous Oxide and want to do the job properly!
1. For road cars & big
bikes with say 25BHP to 45BHP extra, a small increase, all that
normally needs to be done is a few basic preparatory things.
Best to do ALL of the
that it is running correctly! If possible, use a rolling
road, with an experienced operator, and if not get an
experienced mechanic to check it over...
- Fit a new set
of COLDER plugs. For example if your stock plugs are
NGK-B7HS, for example, then use NGK-B8HS or 9 even, instead.
This is one to two grades cooler. They need to be gapped about 10 to 20
percent less than stock plug gaps were originally. This has no
"noticeable" effect on power, but means that when the Nitrous
is operated, the standard ignition system can still cope with
the higher effective compression ratio and still spark. Also if your plugs are
"projected nose" type, fit NON projected nose ones!
Ideally you want the shortest electrodes you can have!
Imagine playing a blowtorch on your plugs. Which bit will
glow first? Answer - the bottom earth electrode! Go for
shorter ones... Or shorten the bottom earth strap and file any sharp edges and
gap across the corner.
NGK plugs if possible. Avoid fancy expensive platinum, or
multi electrode types.
QUALITY HT leads, Stock or preferably NGK plug leads
because they are good!
Make damned sure your fuel pump is
good enough! Drive flat out, open (operate) the fuel
solenoid alone complete with its jet, and make sure the car or
a) still performing properly,
b) That there is the correct amount of fuel still
flowing from the fuel solenoid! - See the jetting sheet. Pump too small
equals melted engine when using Nitrous.
Distributor cap is clean (or new) Sparking is more "difficult" under
the extra effective "compression" of Nitrous Oxide. So, if the spark can track
somewhere else it probably will do! This can cause bangs, pops, backfires, and
lack of power and flash backs that damage carbs and air boxes.
and filter - use high quality synthetic oil like Mobil 1 or Castrol RS Synthetic,
compression tester to be sure no valve leaks exist.
A leaky inlet valve can cause manifold explosions, and a
leaky exhaust valve will glow and melt and can initialise
the onset of detonation in that cylinder.
pressure against the
specifications to try and rule out big end and main bearing wear or
other related problems
Check gearbox/diff oil levels!
- You should do this anyway!
OCTANE fuels. The best you can get. Super
Unleaded, 5 star, or whatever has the highest Octane rating
in your local fuel station! This is important! Or if
you want to add some additional octane booster that will also help
protect your engine from detonation.
If a cooler thermostat and/or fan
switch is available then fit them! A cooler
engine will be less likely to detonate or pre ignite the
mixture in the cylinders, and it should make more power too.
2. For anyone
interested in going further than the 20% to 40% percent
boost, like 50% upwards, up to maybe 300bhp and 500bhp+
boosts, for racing. First read the section 1 above!!!
Then consider this list.
A few other
things are essential or worth considering - depending on
engine and its purpose and how far you are going to "lean"
on your engine...
Forged pistons with
flat tops are the ideal for heavy Nitrous use. They
should have the bore bored maybe an extra 1.5
thousandths of an inch oversized, plateau honed
(bored and then only lightly
honed to leave the boring tools "valleys" for the oil to
sit in) Ideally you need a little extra
running clearance because the pistons will get hotter
than in stock applications and will expand more. Better
also to choose pistons with stronger or thicker top ring
located a little lower down the piston than a stock one.
Head Gaskets can
fail due to higher pressures. The excessive pressure is
often caused by the ignition timing being too far
advanced when on the Nitrous, especially at low to
medium RPM's. So if in doubt retard the ignition timing,
at least at low to medium RPM! If you are still
having head gasket problems that are NOT related to your
ignition timing then a stronger, copper or aluminium
gasket may help. If not then O ringing the top of the
block may be the only answer. Make sure you are using
NEW studs/ head bolts where this is an issue. But its
normally caused by too much advance! You want high AVERAGE cylinder pressure NOT
high PEAK pressures!!! High Peak pressures are only good for breaking
engines and for causing detonation due to the rapid pressure spike before top
Getting the power and getting the oxygen and fuel in the
cylinder is no longer a problem! So forget bigger inlet
valves, big carbs etc. Stock inlet valve/cam is fine. But... Getting 3
times the amount of exhaust gas out through the same
small exhaust valve is a problem...
Stock inlet cam (or
cam timing) is fine. As above we now no longer have an
issue getting the charge into the cylinder. But we do
have one getting it out! An exhaust cam (or cam timing)
that opens faster, further, helps a little. Advancing
the stock exhaust cam (as is possible on a motor with
separate inlet/exhaust cams) a few degrees is also
beneficial because you are opening the valve while the
pressure in the cylinder is higher. This obviously
wastes some of the extra power, but generally the
benefits outweigh the losses - at least on the bike
engines I tried this on on the dynamometer with big 140 bhp plus extra on stock
Exhausts For serious
power outputs when on BIG HITS of Nitrous Oxide, bigger
is definitely better. Big headers, tapered or plain big
pipe work is really better! With out any silencing. This
obviously is not practical on the road!
is not really an
issue as you will be only using Nitrous in huge amounts
for short periods. But a cool thermostat, good fans and
lower general block temperature will allow more Nitrous
Oxide to be used before detonation becomes a problem...
Fuel - Use the highest octane fuel you can
get. C14, C16 race fuel, Avgas 101LL, ETC. The octane
rating of the fuel is a direct measure of its "anti
knock" value. Knock is the onset of detonation caused by
the fuel "self igniting" due to temperature / pressure
in some part of the cylinder causing one flame front,
and another caused by the spark plug colliding! This is
"pinging, or pinking" This gets more violent and causes
all the fuel to "detonate" at once. If this happens when
you are using Nitrous then kiss your engine and wallet
goodbye! The detonation limit is the thing that puts a
very firm limit on the final maximum power output.
Adding Methanol to your fuel increases the fuels
effective octane rating lots! BUT IT MAKES IT RUN LEAN!
So if you try this then remember to add MUCH bigger fuel
jets! Its also possible to run the engine on Petrol, and
the Nitrous system with Methanol... If you do, you will
need jets around 2.2 to 2.5 times as big. But it will
almost remove the possibility of detonation.
Pumps Bigger is
always better here! A pump that's too small causes you
motor to run lean. This is bad! When you think the
pumps big enough, get another one and connect them both
the term NOS is incorrect as this refers to an specific
company (called Nitrous Oxide Systems, in the US)