Hi All,
Does anyone know if it is possible to run an 2002 impreza without a dump valve?

Cheers

 

As a previous owner put a loud one on? If so and you don't want the noise then see if you can get hold of an original unit. These recirculate the airflow back into the intake pipe so it is quiet.

 

Ive got a standard unit aswell but i was informed you could run cossie's without a dump valve and they used to boost and perform better and wondered if it was possible with a scooby

 

If you have a TD series turbo then it would be fine, unless its a VF series turbo then i would'nt. Im assuming you are after the chattering noise?

 

How do you tell the difference in the series?

 

look at the band that holds the core together,if its vf it will say ihi onit if not then td mate

 

You can run any turbocharged car without a dumpvalve if you really want to, but the question then becomes how long it can deal with the knock-on effects of doing so - which include an increase in stress on the turbo bearings and compressor wheel, and shock loading on the airflow meter. These may be slight enough to ignore, or they may be more serious.

Whatever may or may not be the case on a Cosworth, an Impreza will not "boost better" with the dumpvalve blanked. You can get small improvements in transient throttle response but the difference is slight - especially if you have a WRX with the TD04 turbo.

If you are on a standard Subaru ECU, sticking with the standard recirculating valve is the better option as far as engine performance and reliability is concerned.

There are plenty of other threads about this subject so a quick click of the search would give you some useful background info. As per Aladdin's post, if you are doing this in search of "chatter", and your username is a clue, you are likely to be disappointed by the noise you will get from removing the dumpvalve on a road car.

 

the later vf turbo's ie vf34/35 are ok to run without a d/v

 

They will typically deal with it for longer than the earlier VF-series turbos but it's not a black/white "yes they will/no they won't" situation. It'll reduce the working life of any turbo. How much of a reduction you get depends on a number of factors, including the design of the bearings in the turbo and the amount of boost you're running. The more boost, the bigger the shock on the turbo when you shut the throttle.

 

Mine has a TD Turbo so it would be better to run a standard dump valve then to balnk it off?

 

Just use the standard recirc. Its better!

 

JGM said the TD series turbos can handle going DVless.

VF series from VF30 onwards can too (New Age fitment therefore younger/less miles)

 

Depends on how you define "better". In most respects - ultimate working life of the components, consistency of performance due to elimination of MAF reversion/damage, reduced risk of something going wrong, running the recirculating dumpvalve is better, yes.

If you have a TD series turbo on a newage car, you clearly have a WRX - with a TD04. Given how small and lag-free this turbo is already, there's no readily quantifiable performance advantage to running without the DV, and what little there might be you would be both unlikely to notice, and not worth the possible downsides. If you were running something with a bigger, heavier (i.e. laggier) rotating assembly, the difference would be more noticeable.

TD-series turbos have always run journal main bearings + 360 degree thrust bearing so are more able to withstand the increased loads over an extended period of time than the ball/roller bearing (or 270 degree thrust bearing + journal) IHI contemporaries. As above though while some turbos will withstand it for longer than others, it will reduce ultimate service life on them all to some degree - although clearly with some the reduction is so insignificant that it doesn't really matter.