quick dump valve question
20 February 2009, 04:50 PM
#1
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quick dump valve question
yes i know everyone hates them , but ................. ive fitted one and now the car runs like **** . yes i know i should take it off but i love the whoosh .
when the car is off , the 4 long holes are closed , but when the car is running the dump valve is open ???? is this right or wrong ????
i thought the dump valve should be closed unless its releasing air , in which case it opens quickly , whooshs and then closes ????
am i being thick ?
when the car is off , the 4 long holes are closed , but when the car is running the dump valve is open ???? is this right or wrong ????
i thought the dump valve should be closed unless its releasing air , in which case it opens quickly , whooshs and then closes ????
am i being thick ?
20 February 2009, 05:36 PM
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I would just like to state quickly for those that don't know, why a VTA (vent-to-atmosphere) dump valve is no good for Scoobs unless specifically mapped in.
Here goes: air entering the into the intake plenum will have been metered by the MAF sensor so the ECU then knows how much fuel to supply to keep a happy A/F balance. When a VTA DV is used as opposed to the standard re-circulating DV this metered air is lost from the system. The ECU does not know this and will still supply the required amount of fuel. You then have very little/no air to burn with the fuel. This excess fuel will then happily slip past your rings and into your sump; a condition known as 'bore wash'.
If you're happy knowing this then by all means carry on but there is NOTHING wrong with the standard DV that is supplied for the car. It works just fine but doesn't produce the chavvy noise that only impresses 15 year old school boys.
Here goes: air entering the into the intake plenum will have been metered by the MAF sensor so the ECU then knows how much fuel to supply to keep a happy A/F balance. When a VTA DV is used as opposed to the standard re-circulating DV this metered air is lost from the system. The ECU does not know this and will still supply the required amount of fuel. You then have very little/no air to burn with the fuel. This excess fuel will then happily slip past your rings and into your sump; a condition known as 'bore wash'.
If you're happy knowing this then by all means carry on but there is NOTHING wrong with the standard DV that is supplied for the car. It works just fine but doesn't produce the chavvy noise that only impresses 15 year old school boys.
20 February 2009, 06:09 PM
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20 February 2009, 07:10 PM
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I got an idea. Record the ...............woosh onto cd, then remove your actual DV, then just drive around listening to it on your ice then at least nobody else can hear it! Only kidding but all I want to hear is the chirp of a flat out WRC car!
20 February 2009, 07:44 PM
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