Wastegate Actuators... Why fit one?
Q: Why fit an actuator, most people use a bleed valve and they are cheaper too! So what are the benefits of an actuator??
A:
The wastegate actuator takes a pressure feed from the turbochargers compressor wheel, which in turn feeds the engine with compressed air. As compressed air, for any given volume, contains more oxygen, the resulting mixture burns more intensely giving more power for a given cubic capacity than a normally aspirated (non-Turbo) engine.
On most turbocharged cars currently in production, the maximum boost pressure which the engine recieves is ultimately controlled by the wastegate actuator.
The sole job of the wastegate actuator, is to act as a pressure relief valve that controls the turbocharger boost output.
The main parts of an actuator are the spring and diaphragm, the spring holds the wastegate shut until the turbo is delivering a predetermined boost level and then opens, allowing the exhaust gas to escape and slow the turbine.
When the wastegate actuator and wastegate itself are new, the engine will reliably produce the full power figures expected from it, however, when they begin to age the constant cycle of heating and cooling has an adverse affect on the spring which ultimately weakens it. This will then allow the wastegate to open prematurely, whilst the turbo is delivering a lower pressure than it should be doing.
The diaphragm itself can fail as well, this can cause severe engine damage due to the turbo having no more boost control, it will literally keep going and going until either the engine management takes over and cuts the ignition or... something gives way!!
Many companies who either try to save money or do not fully understand turbocharged engines, carry out tuning of a turbocharged car by fitting a bleed valve with your old, worn, standard wastegate actuator. These introduce a controlled air leak into the wastegate actuator pressure line so that the turbo has to produce more boost to open the wastegate due to some boost leaking away. Bleed valves when used by professionals are fine, but they must only be used with an actuator that is up to the job.
For example:
Do you really think that old, worn out 4psi spring in your actuator will keep the wastegate shut on your tuned engine with 16psi of boost pushing against it?? Just watch the boost gauge if you have one and you may see the boost climb rapidly to a peak and then drop off substantially, this is the wastegate actuator spring being overcome by the boost pressure and exhaust gas pressure in the turbine housing forcing the wastegate to open regardless of your wastegate actuator spring!
When requested, our upgrades will include a wastegate actuator of the correct poundage to keep that wastegate closed, until it is required to open, giving you maximum boost at all times, even at peak load! We have teh largest selection of -31 and -34 wastegate actuators in teh world and all are assembled to O.E. specifications in genuine pressed steel canisters.
Our wastegate actuators are from the largest actuator manufacturer in the world.
Before you consider an alternative brand of actuator, check the quality, is it a pressed steel can like ours that guarantees no leaks or is it a cheap alloy one famous for working loose and destroying engiens when it starts leaking? Does it contain a Kevlar reinforced diaphragm like ours, or a cheap rubber one that will tear after 6 months? Is the spring of a sufficient grade to withstand years of heating, cooling and compressing, or will it weaken after a few months use?
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