Pug106 Engine Tuning (Performance Camshafts)

Piper Cam in Production

By changing the the camshaft(s) in your cars engine, you can completely alter the way that the power is delivered by the engine in your car. Power, is usually gained with the expense of torque lower down in the rev range, therefore giving the car more performance in the higher revs.

The aim of the standard camshaft(s) would have been to provide the driver with a fair bit of low rev torque and not to stress the engine too much as well as to give good fuel economy and lower emissions. This means that there won't be quite so much torque higher up the revs, which is where power is obtained.

When you change a cam you need to consider the duration, which is the amount, measured in degrees that the cam holds the valve open for. Another aspect is the lift, which doesn't really make a difference on its own, but is more for fine tuning a cam of a certain duration.

Also, before you even consider a cam job, you must decide on what state your car is currently in and what you intend to have done by the time your engine modifications are complete. If you currently have no other modifications on the engine, then a cam swap is not advisable, as there is not much to be gained and equal power gains can be had in a more appropriate manner, such as with a performance exhaust and sports induction system.

Mild Road Cams

By going for a moderate profile (mild-road spec - 270o) you can get a small gain in power without much loss of torque in the lower revs. This is the advisable limit for otherwise unmodified engines as any longer a duration would result in the engine not running correctly.

Fast Road Cams

A slightly higher profile (fast-road - 285o) is the cam which most road users will go for, as it will allow a good performance gain which is still drivable and useable on the road. However at this stage other modifications will need to be carried out, such as gas-flowing the cylinder head, fitting a performance exhaust (preferably with manifold), a sports induction system or throttle bodies, and some ECU modifications.

Race / Rally Cams

Higher profile cams (race / rally - 300o - 360o) mean more high end power, at the expense of low end torque, so if the car is intended for any form of city use high profiles are not recommended. When fitting a cam of this duration all the above modifications will need to have been carried out, otherwise the car will not be usable at all.

When considering a cam swap, make sure you want to do it, as you may not like the new characteristics of your engine, and you run the risk of making the engine undrivable at low speeds with a lumpy and unrefined (lumpy) torque curve, although by going for a mild-road or fast-road setup should not cause any great loss as long as the other modifications are carried out.

Vernier Pulleys

By using vernier pulleys, the cam timing can be set up to get the most from the cam swap. On the GTI engine the cam timing has seen power gains of up to 10 bhp so it is advisable to fit them when doing the work on any engine.

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