Quote:
Originally Posted by Luke.mansell
I've recently installed a Cold Air intake, and not being so clued up mechanically on cars as of yet I didn't know how to tell if the car had a BOV installed as stock since it has twin turbos?
My next question would be is it worth installing a BOV if it doesn't currently have one, to increase turbo noise and to produce the "whoosh" as it releases air pressure?
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Hi Luke,
Short answer: no, it is not worth installing a BOV. In fact, it could worsen your car's performance. Most diesel engines, including the N47 turbo-diesel in your X1 23D, do not come with a BOV as it is not necessary.
In turbo-gas applications, a blow-off valve is required. When the throttle is suddenly closed, pressurized gas builds up between the turbocharger and a closed throttle body. Without a blow-off valve, compressor surge AKA "turbo flutter" occurs, causing the famous stututututu sound. Much to the disappointment of every Fast & Furious fan, this is very bad for the turbo.
Diesel engines generally do not have throttle bodies, which allows air to freely enter the engine. As such, excess pressure is less likely to build up and most diesel engines do not encounter the issue of compressor surge.
Even if you are just chasing the sound of blow-off, installing a BOV would bring no functional benefit to a diesel engine. By reducing the amount of air entering the engine, a richer fuel mixture could be present, which would reduce fuel mileage, lessen power, and increase emissions.