17 replies to this topic

[vxfarney]

all this talk about dump valves "not working" sames to be a myth. i asked on here why no one has a dv fitted to there vx and was led to beleve that the car wound'nt run right. well myth busted i fitted a dv to my car about 5 weeks ago and it is running spot on. iknow alot of vx owners dont like the sound and that is fine but i do and am glad i ignored the advice and fitted it. dont get me wrong i do repect and rely on the info i get on this site but was just wondering how many people answer questions with info they have heard not what the have tested and know what works and what dosent

[m4t7y]

If I had a VXT I would fit one. Had one on my RX7 and RS Turbo and thought they sounded fine.

[The Batman]

good on ya mate. do what you want not what others tell ya!

[wickywire]

The vx sprint had a dump valve but the sensus of old (about 4 years ago) was that it was chav or boy racer like and had no real benefit to the car. Some had them others not. I remember a certain Lightening having blue neons and that was quashed quickly too

[mandarinvx]

I think this is part of the reason:

The unique sound caused by a blowoff valve (but not a compressor bypass valve) sometimes comes at a price. On a car where the blowoff valve is mounted after the mass airflow sensor, venting to atmosphere confuses the engine control unit (ECU) of the car. The ECU is told it has a specific amount of air in the intake system, and injects fuel accordingly. The amount of air released by the blowoff valve is not taken into consideration and the engine runs rich for a period of time. Engines with a manifold absolute pressure regulated ECU or where the blowoff is mounted upstream of the MAF sensor are not affected.

Typically this isn't a major issue, but sometimes it can lead to hesitation or stalling of the engine when the throttle is closed. This situation worsens with higher boost pressures. Eventually this can foul spark plugs and destroy the catalytic converter (when running rich, not all the fuel is properly burned in the cylinder which can allow unburned fuel to combust upon contact with and melt the converter or to cause incompletely combusted fuel to leave heavy carbon deposits).

One way to correct this problem is to reduce the boost going into your engine. This will cause the piston in the blow off valve to only open slightly. Another way to correct this problem would be to plumb the MAS after the BOV.

Taken from Wiki, so looks like it depends where it is positioned on the VXT

[Baron Von Scubadaddy]

can I get one for my NA

[tangerine_sedge]

can I get one for my NA

I always just wind down my window and shout "SSSSSHHHHHHHHHHHHH!" everytime I change gear.

[Tolksee]

can I get one for my NA

>>> Yes, but you have to have a Supercharger as well. <<<

(But it only costs £160 for the Supercharger and dump valve, so it's incredibly good value.)

Quality:

[MartinS]

I drove a tweaked Regal vxt and that had a dump valve. Did sound a bit like driving Ivor the engine, but either way seems they must think its technically ok. Martin s (Though being Regal, doesnt mean that its necessarily a good idea).

[techieboy]

Nah, don't believe the hype about those supercharger thingies. In my experience they don't really add that much. This is what you want. 80W of sheer unadulterated POWERRRR!

[Pugley]

I drive an NA with a blow-off valve. It's fitted to the driver and sometimes suffers follow-thru. Not a good idea in bucket seats! On a more serious note - they make a chuffing/hissing noise but wont improve performance - just like many of the other intake and exhuast modifications available on the market. Who cares - if you like the sound fit one

[speedster]

IMO dump valves work best on large trucks... recycle.

[TurboTomato]

all this talk about dump valves "not working" sames to be a myth. i asked on here why no one has a dv fitted to there vx and was led to beleve that the car wound'nt run right.
well myth busted i fitted a dv to my car about 5 weeks ago and it is running spot on. iknow alot of vx owners dont like the sound and that is fine but i do and am glad i ignored the advice and fitted it.
dont get me wrong i do repect and rely on the info i get on this site but was just wondering how many people answer questions with info they have heard not what the have tested and know what works and what dosent

Well that's a convincing argument you've put across, I'm sold

[Code Monkey]

all this talk about dump valves "not working" sames to be a myth. i asked on here why no one has a dv fitted to there vx and was led to beleve that the car wound'nt run right.
well myth busted i fitted a dv to my car about 5 weeks ago and it is running spot on. iknow alot of vx owners dont like the sound and that is fine but i do and am glad i ignored the advice and fitted it.
dont get me wrong i do repect and rely on the info i get on this site but was just wondering how many people answer questions with info they have heard not what the have tested and know what works and what dosent

hat are the rolling road results before and after?

Just curious on what gains you have seen, from fitting this so that you know it is working....

[speedster]

Can effect Mass Airflow Sensor readings (amount pending of the level of boost at discharge) and most ECUs are not programmed to handle this type of activity so its usually negative in terms of performance gains.

[TangoAlpha]

There's a major difference between "working" and "improves performance".

[Richy]

Theres also a major difference in 'working fine now' - and 'working long term'. If it's what you want on your VXT then i hope it works out for ya - i've read a ton of things on here that warn you not to do something - but when you do it, it all works fine. Wider fronts without spacers was one, home made air filter mod was another - and don't mention aftermarket wheels - you'll go straight to hell.

[cheeky_chops]

guide on DV fitting from courtenay. Not for me, each to their

http://www.courtenay...?...oc&docId=65

re affecting AMM/running:

The dump valve for these engines must be a twin piston unit as the car has air mass metering. The twin piston unit stops the valve breathing un-metered air on vacuum, confusing the engine ECU.

Edited by cheeky_chops, 14 July 2008 - 11:28 AM.