HOW DOES MY ENGINE MAKE POWER?
engine needs three key things to work - fuel, air, and an ignition
spark. A mixture of air and fuel is drawn into the cylinders which is
then compressed by the pistons. A spark from the ignition system is
then released creating a violent explosion. This forces the piston
down, producing power to drive the car.
To get an engine to
produce a high power-to-capacity figure, the air, fuel and spark timing
need to be delivered within exacting parameters. Crucially, the air and
fuel must be mixed within each cylinder at a ratio which makes the
mixture highly volatile. And the spark delivered at maximum
compression. The larger and more violent the explosion - the more power
HOW CAN I GET MY ENGINE TO PRODUCE MORE POWER?
By getting a greater quantity of
air and fuel in the cylinders. Theoretically, the more air you can
squeeze in, the more fuel you can flow and so the larger and more
powerful the explosion created.
More fuel must be flowed into
each cylinder charge, without upsetting the air/fuel ratio which makes
the mixture volatile. This means the amount of fuel you can flow is
limited to the amount of air you can get in.
There are five ways to get more air in:
Replacing the standard air-box and paper panel-filter with a high
quality induction kit, will help draw in dense, cold air and minimise
b) By increasing the cylinder`s diameter and fitting
pistons of a matching diameter, the engine`s capacity will be
increased, allowing more air to be flowed.
c) By fitting high-lift, long-duration cams more air can be drawn into each cylinder.
d) By fitting a turbo or supercharger massive amounts of air are forced into each cylinder charge.
e) By fitting nitrous-oxide injection the air charge becomes incredibly dense whenever the system is activated.
WHAT IS THE BEST WAY TO IMPROVE POWER ON A TIGHT BUDGET?
Getting an extra 10 to 20 percent
more power will not be too tough or expensive. You will need to fit a
free-flow air filter or induction kit, a full, performance exhaust
system and either a chip or mechanical fuel riser. This is known as a
Induction kits use high quality cotton-gauze
or foam filters. These cause less restriction to air-flow than the
standard paper element filters and, if regularly cleaned, will not need
Although less-restrictive, the primary way in which these
kits gain power is by drawing in cold air. Cold air is more dense,
allowing more fuel to be flowed for extra power. But be aware - if they
are unable to suck on cold air, you will not benefit from extra power.
Fit an induction kit without the necessary cold-air pipe, and it will
draw in less-dense hot air from the engine bay. In this situation no
extra fuel can be flowed and power can be lost. So set-up is crucial.
Performance exhausts gain extra power by reducing the restrictions faced by escaping exhaust gasses.
systems are designed to keep noise levels to a minimum and ensure a
smooth power spread. Noise levels are dropped by forcing the air to
weave through numerous baffles. Power spread is achieved by the pipes
having tuned diameters and manifold lengths. Both of these factors
reduce top-end power.
Performance systems do away with the baffles,
reducing restriction and increasing power. They also use large bore
pipe-work and, in some cases, equal length manifold tract lengths -
again increasing possible power levels. But this is at the expense of
noise levels and bottom end torque loss.
With cold, dense air
flowing in and waste gasses racing out of the engine freely, the engine
will be running on a slightly lean mixture. This can be corrected in
one of two ways. By either replacing the ECU master chip with one
tweaked to cope with the filter and exhaust mods or by fitting an
adjustable fuel-regulator. Whichever you decide to go for, you will
have to ensure the car is set-up properly. This means a visit to a
rolling road where they can check the gasses and make any necessary
adjustments required for maximum power gains.
kits desperately require cold air to perform, so if you regularly drive
in city traffic - where getting heaps of cold air to flow through a
pipe to your filter is nigh on impossible - simply upgrade the panel
filter with a high flow version.
If you spend more time on open
roads, an induction kit to replace the airbox is the way to go. Ensure
your kit comes with a cold air pipe to bring air from outside the
engine bay, to the filter.
City drivers should go for a Cat back system, maximising top-end power without losing any bottom end grunt.
you spend more time on open roads, you should consider a full system,
including tubular-steel manifold to maximise top-end gains.
Chips and Fuel Risers
product you decide to go with will depend on the type of car you drive
and what type of mods you intend to make in the future.
Some cars will not have re-mapped chips available, so an adjustable fuel-regulator would be the only option.
WHAT`S AFTER STAGE-ONE MODS ON A NORMALLY-ASPIRATED MOTOR?
Getting an extra 25 percent more
power will not be easy or cheap. For stage-two you will need to fit a
`fast road` cam or cams with massive lift and long duration; a set of
quad throttle bodies; and have the ECU custom mapped.
Be aware though, to get big power in this way you will have to make drive-ability compromises - however small.
you will need to consider having your engine`s head flowed as there
will be no point in going any further if this part is causing flow
restrictions. Your tuner should have a good idea of what work will be
needed here. It may be the ports and valves in your engine have been
designed really well and there is no room for improvement, but this is
unlikely on all but the best of engines. Whilst being flowed the head
may also require a skimming to increase the compression ratio - a good
idea when fitting lairy cams.
Next up you will need some fast
road cams. The cams` duty is to operate the valves, allowing the air
fuel mixture into the cylinders, and once burnt, out to the exhaust.
The lobes that open and close the valves can be modified to allow more
air and fuel into the cylinders and out to the exhaust.
of a high lift, long duration cam can make the engine run lumpy at
idle, torque will be non existent until the revs rise above 2500rpm,
and the power won`t kick in until the needle rises above the 4500 mark.
But when you get past 5000rpm, all hell breaks loose.
throttle bodies will further enhance airflow into the engine and are,
in fact, the only option if you want to obtain maximum bhp without
going to forced induction (turbo or supercharger).
standard air filter with a free-flow part will improve flow. An
induction kit sucking on cold air will further enhance performance. But
with both of these, the main flow restrictions remain - the airflow
meter, the standard throttle and the original manifold. Junking these
in favour of quad throttle bodies is the ultimate answer.
flow maximised, both fuelling and ignition settings will need to be
taken care of. This can be done by having a new `chip` created for the
car`s ECU or by running a custom-mappable ECU.
If you go for the
plug-in `chip` route you will need to have it custom mapped - as in
pre-programmed state they will not cope with all the modifications
Don`t go straight for a race spec cam
- this will leave you with a serious lack of torque at low rpm levels
and possible loss of power up to 5,000rpm.
You should make a compromise by selecting a cam which gives a little less peak power, but improved mid range gains.
The head-flow shop or cam manufacturer should be able to help out with the ideal choice for both you and your engine.
will have few choices when it comes to the purchase of throttle bodies
as there are only a couple of companies manufacturing them.
engine type has not been converted before, you may also be faced with
having a custom manifold manufactured. The company doing the conversion
will be able to arrange this for you - but it will bump up the overall
cost, so ensure you ask about manifold availability when ordering.
you should be looking at a replacement ECU which can be mapped to run
all the necessary systems. You could run a re-programmed chip, but a
mappable ECU`s parameters are massive and can be easily tweaked should
any further mods be carried out.
Either way, the mapping will need
to be carried out by a team who know their electronic salts. This is no
easy job, it`s not something to be messed around with by a home
WHAT`S AFTER STAGE-ONE MODS ON A TURBOCHARGED MOTOR?
Getting an extra 35 percent more
power will not be too hard, but it won`t be cheap either. You`ll need
to strengthen some key components - most importantly the head gasket
and head bolts. And then install the performance goodies - including an
uprated intercooler, a boost controller and some fast road cams.
you ever see a turbo-charged car pulled up on the side of the road, you
can put your money on its head gasket being blown. Replacing the
standard composite gasket with a steel version will prevent your car
from blowing its top on a regular basis.
Whilst the head gasket is being replaced you may want to consider up-rating the head bolts as well.
up, you`ll want to locate an uprated intercooler. These work in a
similar way to a car`s radiator - except they cool the temperature of
the intake charge. Not only will this cooler air-charge help prevent
detonation, piston meltdown and other nasties, it also enables more
fuel to be pumped in thanks to the air-charge being more dense.
also want to increase the boost - this will gain you an instant rise in
power and torque. Just how much boost you can run will be dependent on
your engine`s compression ratio and general state of wear. Your tuner
will be able to advise on how far you can push your standard set-up,
and also advise on the work required if further boost is craved. But be
aware that reducing compression can be an expensive business - a set of
low-compression forged pistons will set you back well over £600.
the boost can be done by having the car chipped, by having the ECU
re-programmed, or by fitting an electronic variable boost control unit.
Fitting a chip will offer a fixed rate of increased boost - and ensure fuelling and timing are altered to cope.
your ECU programmed is a good idea for anyone who has made loads of
modifications. But it can be time consuming and costly to get the
mapping right throughout the rev range.
Variable boost controllers give the owner the ability to continually alter boost levels for extra or less power.
a set of high-lift cams will show gains in both mid-range and
peak-power. If you go for a set of well developed cams, the exhaust
valves will be opened up early - helping to spin the turbo up quickly,
reducing the lag often experienced with turbochargers. That said, a set
of badly designed cams will completely ruin your car`s overall
performance - so tread carefully and don`t go too extreme.
a metal head gasket fitted may seem like an expensive job, but it will
save you plenty of cash in the long run. Whilst the new gasket is being
fitted, you may also want to uprate the head bolts to a set more
capable of handling higher boost levels.
the best components to consider when addressing engine durability and
power out-put is an intercooler. Not only will a well designed
intercooler protect your engine from numerous foes, it will also help
generate extra power.
There are some forms
of mechanical boost controller, but for the ultimate set-up, a
combination of having the ECU re-programmed and having a variable boost
controller fitted can`t be beaten. You will be able to adjust the
levels of extra power to your needs. Look out for systems that offer a
15 second `over-take` boost at the touch of a button - a great safety
You want cams which have been designed,
developed and manufactured by a specialist tuning company or cam
manufacturer. Preferably a company well known for their tuning
abilities on a specific engine - your engine.
Ask around before you
buy. Speak to tuners, clubs and specialist magazines. Take note of
their knowledge and you won`t be disappointed.
I’M HUNGRY FOR MORE!
There is only one modification
which falls into this category - nitrous injection. It`s cheap,
furious, fantastic for quarter mile competitors and, best of all, it
won`t affect your cars round town (low rpm) drive-ability.
Injection kits have been developed to the point where they are totally
safe - as long as they are installed properly and used infrequently.
Nitrous Injection kits work by squirting nitrous gas into the engine`s
intake charge. Nitrous gas is extremely dense and therefore enables
loads more fuel to be pumped in without affecting the air/fuel ratio.
This creates a monumental explosion in the cylinders, expanding the
mixture by massive proportions - pushing the pistons down with furious
anger. The more nitrous gas injected, the more fuel can be flowed - the
more power is made. The gas is stored under pressure in a cylinder
bottle, usually fitted in the vehicle`s boot. And a line feeds the gas
through to the injectors. To cope with the ultra-dense gas an extra
fuel injector is also added. Most systems will need to be activated by
flicking a switch, but the nitrous will not start flowing straight
away. How and when it kicks in will depend on what set-up you have
installed. You can opt for a mechanical delivery system - which will
wait for the throttle to be opened beyond the three quarter mark. Or
you can buy an electronic delivery system - which will deliver the gas
once you have reached a safe rpm.
If you have the budget you can
even buy an electronic set-up that delivers the gas in stages, i.e.:
25bhp @ 4000, 50bhp @ 5000 and 100bhp @ 6000.
Nitrous Injection Kits
be set-up to offer increases from 20bhp to 300bhp - it`s a simple
matter of changing the jets used to squirt the gas. But do yourself a
favour, start small and work your way up. Always keep in mind your
clutch and drive shafts` ability to cope with such a fierce increase in
power. Nitrous gas refills are expense. It is easy to get through a
bottle if you activate the nitrous every journey. Try and restrain
yourself to using it as a last resort or as a drag-strip weapon.
There are plenty of further
modifications that can be carried out to enhance the performance of
your petrol engine. Five common modifications include replacing the
stock cams with Vernier pulleys; the exhaust Cat with a performance
version; the ignition leads with some that can deliver a more
aggressive and regular spark; the power steering, alternator and air
conditioning`s drive pulleys with lighter, under-driving pulleys; and
by the use of thermal controllers.
After making engine modifications
the stock cam setting may not be delivering maximum power. Replacement
vernier pulleys allow the precise adjustment of camshaft timing for
optimum power output. Gains of around four bhp can be made from this
Performance Cats remove a lot of flow
restriction in comparison to an original equipment Catalyser - without
increasing emissions or failing MOT test requirements. Gains of up to
five bhp can be attained.
Performance ignition leads only
produce more power when a car`s standard leads find your other
modifications hard to cope with. Most turbos running high boost and
aspirated engines running wild cams will benefit from performance leads.
if they don`t increase peak power, they will at least reduce bogging,
misfires and other annoying traits that arise from a struggling
ignition. Expect a maximum of four bhp.
under-drive pulleys reduce the amount of load placed on the engine to
drive systems such as the alternator, power steering and
air-conditioning. This in turn releases more power - up to seven bhp.
controllers help keep heat within components which need to be kept hot
(such as a tubular manifold) and keep heat away from products which
need to be kept cool (such as an intake pipe). By wrapping the exhaust
manifold and shielding the intake pipe, a gain of up to five bhp can be
had. More importantly, your car will not lose performance when things
get hot under the bonnet - when you are driving it hard.
Don`t forget your engine will want setting up on a rolling road by a good mechanic.
Ensure you get the correct part - it`s a pain to find you have mismatch when your car is on a ramp with its exhaust system off.
Ensure you buy a set tailored to your car`s engine. In general, you get what you pay for - low price means low quality.
cars can run these with no problems - but be aware of light-weight
crank pulleys. Your car may use the crank pulley as a harmonic
resonance damper. Ask both tuner and manufacturer as to whether your
car`s engine has a harmonic damper and if the use of light pulley would
These wraps and shields may not be the most exciting products to buy - but most motorsport teams use them, because they work.
Next time more on brakes and suspension!