the way i see it is any thing that doesnt run an intercooler doesnt run a bov, like 3tgte's, maxima's vl's, put an intercooler on and you get flutter/does.

 

i have had a turbo setup with no intercooler and a bov, it blew off, blocked it off and made some retarted noise, put in a cooler and dosage come,

 

each to there own

you can also hear a does before it goes boom and lets remember these things run 40psi++++

Diesels don.t have a butterfly so they don't need a bov and they limit the boost by the size of the exhaust, intercooler is just being lazy

 

Normally diesels have internal waste gates or vein vane control.

^ correct a moundo

finally found a video that shows true compressor surge, and not flutter

this is what you don't want, whereas flutter is for the kicks

 

I have read in more than one place now that factory blow off valves are to reduce noise when the throttle shuts, which if true is really ironic

also all factory blow off valves are recirculating / plumb back as far as i know

Edited December 4, 200916 yr by styler

I have read in more than one place now that factory blow off valves are to reduce noise when the throttle shuts, which if true is really ironic

 

 

If they're plumbed back you really can't hear them.

Surge is explained on the garrett website,

 

they supply detailed compressor maps for each turbo so surge under load can be avoided.

 

on the topic of bov. From the garrett website:

Surge is also commonly experienced when the throttle is quickly closed after boosting. This occurs because mass flow is drastically reduced as the throttle is closed, but the turbo is still spinning and generating boost. This immediately drives the operating point to the far left of the compressor map, right into surge.

 

Surge will decay once the turbo speed finally slows enough to reduce the boost and move the operating point back into the stable region. This situation is commonly addressed by using a Blow-Off Valves (BOV) or bypass valve. A BOV functions to vent intake pressure to atmosphere so that the mass flow ramps down smoothly, keeping the compressor out of surge. In the case of a recirculating bypass valve, the airflow is recirculated back to the compressor inlet.