You need a wastegate on your exhaust side to regulate the amount of boost.  Without it, you could overboost and create detonation   A pressure relief valve is used to prevent overpressuring the intake side if you slam the throttle shut.  It does not regulate the amount of boost.  If you are always careful to close your throttle slowly, you may not need a pressure relief valve, but you should always have a wastegate. See the links below for more info.

 

https://www.onallcylinders.com/2017/01/19/wastegates-vs-blow-off-valves-whats-the-difference/

 

https://grassrootsparts.com/blogs/technical/blow-off-valve-vs-wastegate

 

https://www.hotrod.com/articles/spotters-guides-wastegates-and-blow-off-valves/

 

Bob Rogers

 

 

 

 

 

Can anyone help me with the following?    With a turbo, can I just use a pressure relief valve and negate the wastegate totally??    Looking for simplicity and weight saving.   Neil.