Let's take a look at ways to tune a car engine and what exactly we mean by engine tuning.
First up we have to accept that there are many different types of engines.
We can only cover generic theory in this article on how to tune a car
and suggest if you want more specific advice you sign up to our car forums where our helpful and friendly members will assist you further.
For many a tuned car is simply one running at peak efficiency and
they would achieve this by a full service and adjustment to factory
For others the aim is to get the car running and performing better
than originally intended. Due to the conservative settings used by
manufacturers and low cost production methods and techniques there are
plenty of opportunities to improve your engine.
Most of Cars owners are interested in maximizing the
performance of their cars. But these methods can also be used to maximize economy by pushing the engine into it's most efficient range.
Your first step is to ensure that the engine is running as it was intended. Change the oil and filter, fit new spark plugs and perform a full service if the leads are old they will also need replacing.
Get the engine compression tested and rectify any major issues like
worn piston rings and broken or worn valves. (Checking the valve
clearance is also a very good idea as this can lose a fair bit of
How to tune a Carburettor Engines
These typically rely on a breaker to distribute the spark with a
crude mechancial advance as the RPM rises. By timing the spark to occur a
fraction earlier you can extract a more complete burn cycle and more
efficiently convert the fuel and air mix into power. Too much advance is
a bad thing as the engine will start to knock.
Generally speaking a trial and error approach can often be used, if
you gradually turn up the advance until the engine starts knocking and
then back it off a bit you will have a good setup.
Getting the right timing and spark duration will help improve power and economy as the engine is running more efficiently.
Using a strobe light connected to the spark plug pulse you can
effectively freeze the engine and see the timing mark. The timing mark
is located at the bottom of the cambelt on the pulley, there is
typically a small groove and a little notch marked on the engine.
If you mark the groove and white notch with some white paint it will
show up when the strobe light hits it. This will enable you to better
adjust the engine timing.
By rotating the distributor housing you can adjust the timing by
advancing it or retarding it. Adjustment should be done gradually and
the engine will need to be tested under load at the full rpm range. A
rolling road dynometer is the best environment for this as you can make
If you want to increase the fuel to match the intake air you will
need to a larger jet (some wrongly refer to jets as needles!). Carb
setup can be a real art and if you have twin carbs then the job gets
even harder. Most carbs come with the correct jet sizes and you should
only uprate them if you want to make dramatic alterations to the engine
and increase the intake air charge significantly.
The key is matching the fuel to air delivery and with modern fuel injection engines this is becoming a dying art.
How to tune a fuel injection engine
Fuel injected engines are much more sophisticated, both the amount of
fuel and the timing of the spark is delivered and is adjusted.
The old mechanical spark distribution was far from ideal and meant
that most of the time the engine was not running at peak efficiency.
Spark timing needs to vary a lot more than a simple linear curve will
allow. So to address this issue we now have a computer in our cars that
stores a fuel and timing map across varying loads and intake conditions
to provide optimum running.
Most modern engines operate on a closed loop which basically means
that the parameters for the next combustion cycle are set by the
previous one. The exhaust is sniffed for oxygen to determine if the car
is running rich or lean and the intake fueling is adjusted to match.
Many popular engines learn over time the optimum settings and every
200 miles or so adjust the ideal map to keep the engine running
efficiently. This takes into account driving style, seasonal temperature
adjustments and varying grades of fuel.
As the fuel delivery and timing map is stored and controlled on
computer there is little a home tuner can do other than replace the chip
or add a piggy back device.
On a naturally aspirated engine you can probably wring another 10%
power out of the engine by tightening up the fuel delivery and timing
maps. Manufacturers tend to set the engine conservatively.
How to tune a turbo engine.
The points about fuel delivery and timing the spark are just
as essential in a turbo engine. All of the above point apply to turbo
engines but the gains are much more noticable due to the effect of the
turbo. As the turbo is pushing more air into the engine and is making
more power you have a lot more to gain.
The turbo is the heart of the engine so we also need to pay attention
to this. Matching the exhaust and intake compression impellers to your
air needs can make dramatic alterations to the power band. You can
hybridise the turbo using a stock OEM turbo casing and uprating the
internals. Another option is to fit a second turbo or just replace the
existing turbo with a larger unit.
It all depends what your power requirements are. See our turbo tuning articles to get more of an idea on what is involved in a tuned turbo engine.
Pre 2000 engines are typcially very hard to remap so you are stuck
with piggy back devices or a risky chip change. After 2000 most cars
came with OBDII ports or similar and these allow a relatively easy way
to upload and reflash the cars computer.
On a modern turbo engine the computer will typically control the
boost and wastegate in addition to the fueling and timing so you have
much more scope for power gains.
A modern turbo engine can often make a power gain of 40% quite easily on stock parts with a simple remap.
Other ways to tune an engine.
Further modifications and links to more information on them. Once you
know about the characteristics of timing it is worth looking at the
many other options and seeing what extra mods can be done to your cars
We have mainly looked at timing so far. There are a large number of
other modifications you can do to an engine to increase it's state of
tune. Balancing your engine allows an engine to run at higher RPM, adding a sports camshaft
will further raise the power band and alter the timing and duration of
the engines induction, compression, bang and exhaust cycles. Moving the
air through the engine faster is also a priority and a set of
performance headers a sports exhaust, sport catalyst and some head work such as porting and polishing will further increase the power band.
If you have a turbo then you also have some additional options open to you. An intercooler will reduce the intake air temperature and allow bigger power gains. You could also uprate your turbo by fitting a larger turbo or get your existing turbo hybridised with uprated internals. Wastegate and blow off control can also be altered to increase the power produced by the engine.
Source : www.torquecars.com/tuning/tune-a-car