Turbo Blanking plate

[T5R_Guy]

What does this do?



Im not 100% up on Turbo chargers. I know the basics. There is something very similar to this on my car. I always thought this was a BOV delete but when I lift off under power I hear the turbo blow off. Where would that be coming from? What would be the advantage of fitting a BOV? You see a load for sale.
Hopefully one of you gurus will write me 'An idiots guide' to help me understand this stuff,
Cheers in advance,


...Guy

[doingitsideways]

That is indeed a BOV blanking plate, or recirc blank plate, or whatever else people choose to call them.

Volvo fit a recirculating valve as standard, as these keep all the metered air in the system when the throttle closes, keep the turbo spinning and prolong its life, but some choose to remove them for various reasons.

Atmospheric dump valves aren't a great idea, as all the air that's been drawn through the MAF and calculated, then gets dumped out when the throttle snaps shut, causing the ecu to throw a wobbler as the mixture is suddenly very wrong.

The noise you're currently hearing is probably turbo stall or chatter.
Nothing wrong with it as such, but snapping the throttle hard closed on full boost doesn't do the turbo much good - imagine a lot of air moving very fast, then suddely can't go anywhere, causes the turbo to stop turning very abruptly. Something like 100k rpm to virtually zero in half a second.

[T5R_Guy]

Thanks Sir. Excellent info. What did that plate delete though? Did Volvo use a kind of BOV. Im still a little confused as to what it does with the pressurised air now?


...Guy

[DunkinBiskits]

it deletes Volvos OE Blow Off Valve. there was probably a dump valve mid boost pipe somewhere at some time previous, the air is now hitting your closed throttle plate then "bouncing" back towards the turbo, slowing it down substantially (not stationary but 75%+ slower than it was a fraction of a second ago), get back out the inlet port, then getting drawn back in, compressed a bit, hitting the throttle plate, "bouncing" back etc etc this is why the noise slows from really frequent "tuh-tuh-tuh" and gets progressively slower as the positive pressure in the boost pipes decreases.

the downside of this is it deforms the turbos compressor blades, resulting in 'lost' boost over time/turbo working harder to achieve desired boost level. it also destroys transient throttle response

got a spare recirc valve here if you wish to re-instate the OE method of charged air control?

Dunc

[T5R_Guy]

Cheers Dunc.

If I put an aftermarket BOV that would save my compressor blades and also give me that lovely chuffing sound. Are they any good? Ive heard lots of pro's and cons to them but, I personally haven't a clue. It would ber good to get an idea from others who might have done this.

...Guy