Back GLE Back GLK Back GLS Back GT-R Back GT-S Back ML Back R Back S Back SL Back SLC Back SLK Back SLR Estimated Lead Time: Days. After many attempts to get the Mopar supplied gasket to seal properly when doing boost leak tests on SRT-4's we decided to make our own. Stainless Steel Cap Head Bolts and washers are included as we know how difficult it is to get a socket on the back bolt durring installs.
Lay the gaskets on a piece of cardboard with the surface that will be touching the plate laying up. A light spray of 3m spray adhesive super 77 on the gaskets before installing makes aligning them much easier. Let the adhesive tack for about a minute.
Carefully pick up the gasket and set onto the Mopar Blue BOV plate aligning each bolt hole and main vent port, the spray adhesive will make installing the gaskets very easy and they will stay in place for the install onto the turbo. These valves are only used on engines with the blow-through turbo setup. For more information on this, see the Turbocharger Concepts page. The BOV is basically a vacuum-actuated valve that opens when sufficient vacuum is present.
Vacuum is supplied by a connection on the throttle body, while the BOV inlet is connected to the turbo output hose. While in boost, the valve remains closed and the turbo pumps air into the engine normally. Without the BOV, when the throttle is closed the turbo is suddenly trying to pump air against a closed throttle plate. This creates a pressure spike in the turbo output hose and sends a pressure "wave" crashing back and forth between the throttle plate and the turbo compresser blades.
The pressure spike quickly slows down the turbo and the pressure wave can actually damage the turbo. On intercooled engines, this pressure wave effect is suppressed but the pressure spike still occurs. When the throttle is opened again, the turbo has to spin up again, creating turbo lag.
If a BOV is present, the BOV will open as soon as the throttle is closed, releasing the pressure spike into the airbox and avoiding the pressure wave phenomena. When the throttle is closed not necessarily all the way , a vacuum is created between the engine and the throttle plate.
Near the throttle plate is a hose nipple that supplies vacuum to the BOV through a device called a "Quick Release Valve". Basically the quick release valve supplies the BOV with vacuum when there is vacuum in the throttle body, and vents the BOV to atmosphere when there is boost in the throttle body while prevent boost from reaching the BOV.
Below is a diagram of a typical BOV while in boost with the throttle open. The spring holds the valve closed, but if enough pressure reaches the BOV inlet, it will be forced open about 15psi. When the throttle is closed and vacuum is supplied to the front of the BOV diaphram, it releases the pressure from the turbo: As you can see, the operation of the BOV is fairly simple.
When the throttle is opened again, the BOV will close because the quick release valve will vent the vacuum inside the BOV. There is a fraction of a second between when the throttle is opened and the BOV closes. When the throttle is suddenly opened, the turbo is usually not spinning very fast and is not providing much boost, if any. There is often a moment where there is actually a vacuum between the throttle body and the turbo because the turbo hasn't "caught up" with the engine's demand for more air yet.
Since the BOV is still in the process of closing, it will often suck some air through the pressure release connection because of this vacuum inside the turbo output hose. This is part of the reason that the BOV is located inside the airbox on the clean side of the filter. If some air is sucked in, it will always be clean air. If you are installing you own BOV, be sure to either put a small filter on the release side of the BOV, or connect it to the clean side of the airbox.
Unfortunately, this BOV has a weaker spring and is forced open at about 9psi. The BOV can be held shut by supplying the vacuum nipple with some boost. Gus Mahon has a vacuum bleed configuration that can accomplish this. You cannot send all of the boost to the BOV because it will rupture the diaphram, which is why his design bleeds off about half of the boost, while supplying it with full vacuum.
It is all aluminum and has a VERY stiff spring. It will not forced open until over 23psi! This BOV has a 1" inlet and outlet, but only has one hose connection because it is designed to be mounted to a manifold. It can be retrofitted for hoses, thanks to Gus Mahon. See Garry Donovan's web page in it.
0コメント