How to size a wastegate


How to size a wastegate

Sizing a wastegate is a critical step to providing a reliable turbo system. learning how to size a wastegate to an engine combination is straightforward-ish. There are many factors that go into the sizing of a waste-gate, but there are some general rules that you can use. Before we get into the discussion of waste-gate sizing let’s spend a few minutes talking about the different types of waste-gates. There are two main forms Internal and External waste-gates.Internal WastegatesThese type of wastegates are usually found in oem applications. For instance the Mitsubishi Evo runs an internal gate. The Internal gates are mounted to the turbine housing (hot side) of the turbo. It is a bypass valve that allows excess exhaust to flow into the downstream exhaust. Control of the signal comes via a pressure port located on the top of the wastegate housing.Sizing of internal waste-gates is not really done because you would be required to modify the turbo housing. There are upgrades for the internal gates, but they are usually not recommended. When we see a vehicle coming to the max flow capability of the internal unit it is time to upgrade to an external version.External WastegatesMost aftermarket applications utilize external wastegates for controlling the boost pressure created by the turbocharger. They provide the same function as the internal versions however they are separated from the turbo housing.

Turbosmart universal internal gate

tial sport f38 wastegate

tial sport f38 wastegate

tial sport f41 wastegate

tial sport f41 wastegate

tial sport v60 wastegate

tial sport v60 wastegate

Internal Wastegates

These type of wastegates are usually found in oem applications. For instance the Mitsubishi Evo runs an internal gate. The Internal gates are mounted to the turbine housing (hot side) of the turbo. It is a bypass valve that allows excess exhaust to flow into the downstream exhaust. Control of the signal comes via a pressure port located on the top of the wastegate housing.Sizing of internal waste-gates is not really done because you would be required to modify the turbo housing. There are upgrades for the internal gates, but they are usually not recommended. When we see a vehicle coming to the max flow capability of the internal unit it is time to upgrade to an external version.

External Wastegates

Most aftermarket applications utilize external wastegates for controlling the boost pressure created by the turbocharger. They provide the same function as the internal versions however they are separated from the turbo housing. They are mounted on the piping that runs from the headers to the turbine housing of the turbo. The location and angle that it is mounted to prevent boost creep but that is a lesson for another day. External gates come in many shapes and sizes and sizing the gate is important. That being said it is not entirely straight forward. For example the more powerful the engine then a larger wastegate is required. Well this is not true…..Mind Blown

Typical Turbo Diagram

 

Sizing the wastegate

Now for the meat and potatoes. learning how to size a wastegate. This can be broken down into 4 general guidelines and a few practical examples.

Small Turbo-engine/Low Boost = Bigger Wastegate

Small Turbo-engine/High Boost = Smaller Wastegate

Big Turbo-engine/High Boost = Smaller Wastegate

Big Turbo-engine/Low Boost = Bigger Wastegate

Pretty straightforward right? Unfortunately there is not a hardened rule for wastegate sizing so you really need to do your research on your exact combination to see what works. The turboforums is loaded with information like this but we will give you a few examples of what will work.

low boost LS motor with a single T4 housing turbo up to 88mm will be able to use a 50mm wastegate

low boost ford modular motors with single T4 up to 76mm can use 45mm. However I have seen high boost 20+psi run smaller

2.0 turbo Honda 38mm will be sufficient for most scenarios

Don’t forget about the boost controller. We manufacture and sell some of the best manual controllers on the market.

Leave a Comment

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>