Vehicle & Technical > Discovery

Dump Valve Question

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Range Rover Blues:
I think the Turbo is a red herring, get the pump tweaked and look at an intercooler upgrade.  Stage 1 upgrade is to soak the one you have in parafin overnight and clean it out.

steve_h:
Dump valves are only really for petrol engines because they have a throttle butterfly. Here's the science:

You have your foot planted and your petrol engine is accelerating. The throttle is open and air (compressed by the turbo) is being forced into the cylinders, mixed with fuel on the way by injectors or carbs. If you lift off the throttle completely (to change gear for example) the throttle butterfly closes, so the air from the turbo hasn't anywhere to go. This causes back pressure and stalls the turbo's compressor (stops it spinning) - unless you have a dump valve. When you close the throttle with a dump valve fitted, it senses this and opens to allow the air from the turbo to escape without stalling. The turbo is then still spinning fast when the throttle is opened again, the dump valve closes and boost is available to the engine straight away.

In a diesel engine you haven't got a throttle butterfly because your engine is controlled by the fuel pump instead, so there's nothing to shut off the flow to the cylinders and stall the turbo.

This is all different to the wastegate which is there to bypass the turbine (exhaust side) when the required inlet pressure (boost) is reached to prevent damage to your engine.

Hope that helps  :D

Cheers,

Steve.

landroverkeith:
ebay did have one a guy was selling alledged a str8 fit for 300 tdi

but once u read the whole bit of his "bolt str8 on component" at the very bottom he added some specialist welding required  :?

Xtremeteam:
fitting a dump valve to a TDI is piddle easy



you just have to know what ur doing,

u need a 12v solenoid & a micro switch,throw in a dump valve & some plumbng & you are half way there

petergalileo:
But the petrol engine dump valve is no good ?

Please explain the proceedure Mike for the unenlightened among us :D

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