I will be explaining how to vacuum test your engine.
This is the engine I will be testing, a Red Top SR20DET
This is the kit I will be using
Compression and Vacuum test kit
Step 1) Find a suitable location to tap into a vacuum line, not a wastgate line.
I used this group of vacuum hoses one that goes to the blow off valve.
Step 2) Pull the hose of choice off
Step 3) My set didn’t come with a T connector so I made one. Use some hose on one side to connect to the male side of the line you disconnected. If you need to make one of these connectors also just go to Home Depot or Lowes and you can find everything you’ll need, make sure you use Tephlon tape to seal the threads.
Step 4) Connect the other end of the fitting adaptor to the hose you pulled off of the male side of the vacuum line.
Step 5) Connect your vacuum gauge to the only male end left
Step 6) Run the engine and check the gauge for fluctuations that could be caused by leaks, check through different RPM ranges.
That’s it, there were no obvious vacuum leaks on this engine, but to be completely sure you would need to do a smoke test.