Mud-club
Vehicle & Technical => Discovery => Topic started by: petergalileo on December 06, 2006, 00:01:43
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Ok, the kids thinking their dad needs to be a bit cooler got hold of a dump valve. They think the woosh is cool ? anyway, they bought one for a petrol motor but I just realised theres no vacuum really on the intake side of a diesel.
I know a little about the turbo system on the 300 and it already has a wastegate, so is there anyway of fitting this dump valve and will it affect the motors performance or just make it sound like a lorry ?
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the (petrol) dump valve will never work no matter what you try
and if you really have to have one they cost around 200-300quid for a diesal dumpvalve and at that price there really aint no point,
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ouch ! I will get a big bottle of lemonade and a loudhaler in that case. Thanks
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http://www.forgemotorsport.com/content.asp?inc=product&cat=0006&product=FMDDV
link to a diesel dump valve
and another with a price
http://www.zen19051.zen.co.uk/prod01.htm
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Ouch again !
What about modifying the wastegate ? where does the air from that go or is it different to a dump valve ?
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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.
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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.
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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 :?
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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
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But the petrol engine dump valve is no good ?
Please explain the proceedure Mike for the unenlightened among us :D
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But the petrol engine dump valve is no good ?
Please explain the proceedure Mike for the unenlightened among us :D
a petrol dump valve & a diesel dump valve are the same :wink:
its just the way you fit them thats different
u need to fit the dump valve into the pressure side if the intercooler plumbing,
u then need to T into the brake vacum hose & to the T attatch the solenoid valve,from this take a small bore hose onto the dumpvalve,this is what makes it open,u then need to mount the micro switch so its full closed at when the throttle is released,u need to put a 12v supply up to the solenoid valve & use the micro switch to switch the earth for the solenoid valve,
then basically when u go from full open to closed in the middle of changing gear the solenoid valve will open & put a vacum to the dump valve & you get a tish 8)
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Thats sounds pretty easy to do, but just to throw a spanner in the works its an auto ! so would only work when throttle is released which suits me, dont want to sound like a bus with every gearchange, just good to show off to the kids and their mates :D