Blow Off Valve For Surge?

[notacarlo]

This is a funny thread. Make it a sticky for the search feature.:biggrin:

 

[notacarlo]

Blowoff valves are used to prevent compressor surge, a phenomenon that readily occurs when lifting off the throttle of an unvented, turbocharged engine. When the throttle plate on a turbocharged engine closes, the high pressure air in the intake system is trapped by the throttle and a pressure wave is forced back into the compressor. The compressor wheel slows rapidly and may even stall, and the driver will notice a fluttering air sound. The rapid slowing or stalling stresses the turbo and imparts severe turbo lag if the driver accelerates immediately after the surge event.

Did you copy and paste that? There is enough clearance in a turbocharger to let air back out without slowing it down "rapidly". Where do you think the air the engine cant use goes when at full throttle? The surge when backing out...there's a way to avoid it. Back out slowly. If you don't, you're just showing off.

 

[GNVYUS 1]

I have a Forge blow off on my Talon and it's easy to adjust the springs and gets the job done for cheap. Forge Motorsport | Alloy Fabrication

I believe the chips have a Decel coding in them so you can vent it into atmosphere without stalling issues.

You'll need a vacuum source to apply to the valve, I wouldn't tee into the fuel pressure reg in fear of a of possible leak etc.

 

[gndoug]

over 150k on stock turbo... no BOV and no issues.

I always believed that the biggest reason BOV's were put on cars was so the turbo would be able to REMAIN SPINNING during shifts, decreasing turbo lag on manual cars. Would I put one on my car... nope. Did I have one on my old supra... yep! But it was manual... and I was in a "stage" that I don't really talk about anymore... lol.