Does the blow off valve go before or after the intercooler?
Turbo cars, at the throttle body. Blower cars, before the intercooler. On a turbo car you wont the escaping air to travel in the same direction as the boosted air, away from the turbo.
Is a blow off valve bad for your car?
A vent to atmosphere BOV can also cause slight over-fueling between gear changes. This is because a portion of metered air is released from the intake system. It is worth noting that over-fueling is not harmful to the engine. It just means the unburnt fuel will exit the engine as exhaust.
Does blow off valve placement matter?
Both placements have their advantages. The closer you get it to the compressor, the quicker it will vent the air from the turbo, and the turbo speed will drop less. Sometimes though, the pressure built up in the upper IC pipe and the intercooler will reverse, and flow backwards through the pipes to vent out the BOV.
How does a blow off valve work?
A blowoff valve is connected by a vacuum hose to the intake manifold after the throttle plate. When the throttle is closed, the relative manifold pressure drops below atmospheric pressure and the resulting pressure differential operates the blowoff valve’s piston.
What happens when the BOV valve is opened?
When the BOV valve opens, it creates a reverse flow of the large volume of air from the plenum and the chargecooler towards the turbo. When the pressure in the duct drops and valve closes, a shock wave hits the compressor inducer in reverse direction creating a surge (which we are trying to mitigate by installing the BOV!).
Which is the best BOV location for a compressor?
BOV location at the plenum (or close to it) may be the best, because it will not create a reverse surge in the pipe connecting the plenum to compressor outlet. Your thoughts?
Can a vacuum pump be used to install a BOV?
Using the lightest spring, adjustment screw all the way out, and no shims/washers, install the BOV. Re-create your peak vac in your intake manifold. You may be able to use a vacuum pump or just let the car idle. If your BOV opens during peak vac, increase the spring energy.
What makes a BOV piston harder to open?
Remember, the only factor that you can really change is SPRING ENERGY. There are several ways to do this. Less spring energy means your BOV piston will open easily. More spring energy means it will be harder to open and more resistant to opening during high-vacuum conditions.
When the BOV valve opens, it creates a reverse flow of the large volume of air from the plenum and the chargecooler towards the turbo. When the pressure in the duct drops and valve closes, a shock wave hits the compressor inducer in reverse direction creating a surge (which we are trying to mitigate by installing the BOV!).
BOV location at the plenum (or close to it) may be the best, because it will not create a reverse surge in the pipe connecting the plenum to compressor outlet. Your thoughts?
Using the lightest spring, adjustment screw all the way out, and no shims/washers, install the BOV. Re-create your peak vac in your intake manifold. You may be able to use a vacuum pump or just let the car idle. If your BOV opens during peak vac, increase the spring energy.
Is there a BOV that vents to atmosphere?
BOV Myth #3: The easiest way to get my turbo car to make a cool “PSSSHHHH” sound is to get a BOV that vents to atmosphere. On many cars, the air is metered by a device called a MAS/MAF before the turbo inlet.