Wastegate

Wastegate

Should you use internal or external wastegate?
This is entirely up to the installation. Both work but external wastegate is more common in 500+ hp builds although an internal wastegate also works. The reason for this is that an external wastegate allows a larger valve/port for the exhaust to evacuate through = better control.

How do you best mount an external wastegate?
Turbosmart installation instructions for external wastegate:

What size wastegate should I use?
This is a complex issue. Factors that must be taken into account include the engine's displacement, type of fuel used, available space for the wastegate (and position/angle), maximum rpm for the engine, number of turbo units, number of wastegates used and desired boost pressure / boost pressure range.
General guidelines:

Big turbo / low boost pressure = Bigger Wastegate.
Big turbo / high boost pressure = Less Wastegate.
Small turbo / high boost pressure = Less Wastegate.
Small turbo / low boost pressure = Bigger Wastegate.

Pressure is given in different units (PSI vs Bar)
Many products indicate the pressure in PSI. Here we have collected some examples / translations:
1 PSI = 0.0689 bar
7PSI = ~0.5 bar
14PSI = ~1 bar

Is the engine producing more boost pressure than the wastegate spring is specified for?
There are many factors that can create more boost pressure than what a wastegate is set to. Common problems are a vacuum leak to the wastegate, an incorrectly sized wastegate for the engine (usually too small), poor placement / angle of the wastegate, or the wastegate being stuck / bunched. These are some of the possible reasons.

Overboost
Better flow through the turbine wheel/exhaust system than the wastegate means the charge pressure cannot be controlled. Make sure there is better flow through the wastegate than the turbo.

Can I test which wastegate spring is installed?
By vacuuming or pressing with a measuring tool through the vacuum port, you can easily see which spring is installed. Note that an installed wastegate also works together with the engine's back pressure and exhaust pulses which means that a 14psi spring does not always open at 14 psi. This is controlled by the tune or by adjusting the spring pressure.

Can you use an angled wastegate arm on an internal wastegate?
It is fine to use an angled bar on an internal wastegate but it is not something we recommend as it can bind more easily as the pulling force does not come completely straight.

How to connect vacuum connections?
Usually, the connection that sits under the membrane (the nearest hot side) is used. If you want to use back pressure, that connection on the other side of the diaphragm is also used.

Wastegate leaks pressure from the valve guide
A small leak here is completely normal as the valve stem must have a certain amount of play to avoid binding. When the valve is cold it leaks more and when it is warm it leaks less. If the valve was made to be completely tight when cold, it would have started to bunch when the material expands from the heat.