Bov close to turbo

[RedMist]

I run two recirc GTR blow off valves. One on each bank, both after the intercooler close to the throttle bodies. We direct all blow off air directly into the intake turbine. I've no noticable lag. This may be attributable to the direction of the BOV recirc air or any number of other engine specific factors. Personally I wouldn't think there would be a huge pressure differential anywhere between the turbo and the TB.

[steve murch]

to run a bov is more important than where but there is some differences.
if you recirc back to the intake just after the turbo outlet the charge air temp is high,close to t/b after the cooler the temp is down.
i on the other hand prefer not to run one at all but theres abit more to doing so without hurting the turbo in the process.

[sergei]

My thermodynamics is very rusty, but please bear with me:

One would think once the air is de-pressurized then it will drop temperature to similar temperature it started with (ambient) + temp gained from turbo inefficiency (isenthalpic process aka irreversible adiabatic process due to drag). Adiabatic process is going in both directions, you compress gas it will heat-up, you decompress gas it will cool.

[steve murch]

My thermodynamics is very rusty, but please bear with me:

One would think once the air is de-pressurized then it will drop temperature to similar temperature it started with (ambient) + temp gained from turbo inefficiency (isenthalpic process aka irreversible adiabatic process due to drag). Adiabatic process is going in both directions, you compress gas it will heat-up, you decompress gas it will cool.

when the discharge takes milli seconds to happen temp doesnt drop allot,the charge air temp from the compressor outlet can be as high as 180c depending on comp wheel eff and boost level

[JustinSpiderholden]

to run a bov is more important than where but there is some differences.
if you recirc back to the intake just after the turbo outlet the charge air temp is high,close to t/b after the cooler the temp is down.
i on the other hand prefer not to run one at all but theres abit more to doing so without hurting the turbo in the process.

what is required not to have to run a blow off valve?

[steve murch]

to run a bov is more important than where but there is some differences.
if you recirc back to the intake just after the turbo outlet the charge air temp is high,close to t/b after the cooler the temp is down.
i on the other hand prefer not to run one at all but theres abit more to doing so without hurting the turbo in the process.

what is required not to have to run a blow off valve?

there's a few different ways and not that easy to explain,
easiest one is to run a throttle body in front of the turbo which is linked to the main t/b on the manifold,you leave the turbo t/b open enough to retain and idle signal.
what this does is allows the turbine to keep spooling as there's no load on the compressor wheel,by doing this even time you close throttle effectively the compressor wheel is allowed to free spine thus without load thus when you hit the go pedal instant response.
there is no vacuum on the compressor end at this time so there's no need to run a carbon seal on the compressor side.
that's one type but as i said the others aren't that easy to explain and one of them is very effective when done right,my own car which has 20k us worth of turbo on it wont be running a b/v.
is saying all this you can build a turbo to help withstand not running one but you must have a pinned comp wheel or locked in some way and it must be billet to help prevent the blades bending backwards with surge.