Wastegate Size Calculator
Enter the power you are aiming for and your target boost, and say whether you run twin gates. The calculator suggests the wastegate valve size and a spring to pair with a boost controller.
- Wastegate size
- Spring
- Internal gate
Pick a spring a few psi below your target boost.
Bigger power needs a bigger wastegate. A 500 hp engine at 20 psi suits a 44 mm external gate with a 14 psi spring and a boost controller. Make the same power at only 12 psi and step up to 45 mm, because more exhaust has to bypass the turbine.
Wastegate size chart
Single external gate, over 15 psi. Search for power.
| Power (hp) | Wastegate (mm) |
|---|---|
| Up to 350 | 38 |
| 350 to 425 | 40 |
| 425 to 500 | 44 |
| 500 to 600 | 45 |
| 600 to 700 | 50 |
| 700 to 900 | 60 |
| Over 900 | 66 or twin 60 |
mm.
Power and gate
20 psi. Slide the power.
The valve grows with power.
How to size a wastegate
Power to gate. Step through it.
Power
Target.
Route the gate's dump tube away from sensors and wiring.
Internal, single or twin external
Wastegate types. Compare them.
Built in.
Common.
Big power.
Boost creep at high revs is the classic sign of a gate that is too small.
Before you buy
Wastegate checks. Tick each item.
Tick each item as you go.
Use a boost controller to run above spring pressure safely.
What you get
Gate sizing. Each tile explains one result.
mm.
psi.
Fine or not.
Adjusted.
Tips.
Gate placement on the manifold matters as much as size.
Frequently Asked Questions
No question matches that search.
What size wastegate do I need?
About thirty eight millimetres up to three hundred and fifty horsepower, rising to sixty for about nine hundred.
What size wastegate for five hundred horsepower?
About forty four millimetres at normal boost.
Why does low boost need a bigger gate?
More exhaust must bypass the turbine to hold boost down.
What spring should I use?
One a few psi below your target, with a boost controller.
What is boost creep?
Boost rising past the target because the gate cannot flow enough.
Is an internal wastegate enough?
Usually up to about four hundred horsepower.
Do I need twin wastegates?
For very high power or twin scroll setups, often yes.
Boost under control
Choose a gate big enough for your power and boost stays right where you set it.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.