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I am building my 1st ever supercharger engine which will be a Honda B20/B16 vtec . I am pretty much ready to go but would like some more info in regards of wastegates on supercharger ?

Is it worth it ? How to choose the right size and the right angle of installation ?

Thank you .

Normally a wastegate won't be necessary in most supercharged applications as the boost is related directly to engine speed. With a centrifugal SC the boost will climb in a linear fashion with regard to rpm while a positive displacement SC provides a relatively constant boost.

We did interview the Mighty Mouse CRX built by 101 Motorsport which runs a centrifugal SC on a K20A. They used a wastegate on the boost pipe to reduce boost in lower gears to control wheel spin.

I'm not sure if you're confusing bypass valves with wastegates though? In a supercharged engine it's common to include a bypass valve to bypass air around the supercharger when the engine is at part throttle/off boost.

That is exactly to the car that I was referring to , as I saw a small post of hp academy on instagram but as I mentioned didn't know if it would be beneficial or not .

Would the use of a wastegate benefit anywhere else besides reduce boost in lower gears to control wheel spin ? Couldn't that be sorted also through the ecu (depending of course on the ecu that some might use) ?

While you could rely on traction control through the ECU, it's always best to try and match the power delivery of the engine to the available traction. This means the ECU has less work to do, and the dramatic amount of intervention that may be required to control run away wheel spin can also upset the balance of the car. My own preference has always been to rely on traction control as back stop rather than allowing it to constantly operate.

Can't we use also boost by gear to fix that issue ? I do understand that you in some occasions you will need less boost on a specific gear and in some other occasions you will need more boost on the same gear , so can't we use also a map activation together with traction and boost by gear to set it up ? Or even a 2 table set up with all the above ?

And if you choose to use a wastegate how do you determine the size that would be suitable for your application ?

Yes, gear dependent or speed dependent boost is the ideal solution but this requires the wastegate installation as discussed - It's not typical to include a wastegate on a supercharger and generally the boost is fixed at whatever the pulley size gives you. You can't change the boost without changing pulley size. Basically if you want to reduce the boost in a lower gear, you need some way of venting the excess airflow and preventing it from reaching the engine.

The size of wastegate you need will depend on the airflow from the supercharger as well as how much you want to reduce the boost.

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