Viewing: Dump valves or blow off valve suggestion for Impreza

blenkarn123 · 23-01-2010, 05:44 PM

I am thinking about fitting either a dump valve or a blow off valve to my Impreza wrx but im not sure which is the best, could you reccomend one and if so what is it?

Thanks

**Poddy** · 23-01-2010, 06:16 PM

i'd recomend a Dump Valve as a BOV can cause the engine to run on a Fuel rich mixture, as the air is vented into the atmosphere

**MasterAuron** · 23-01-2010, 06:22 PM

HKS SSQV ftw!

***old-git*** · 24-01-2010, 01:44 AM

Spend your hard earned money on something actually useful.

***old-git*** · 24-01-2010, 01:47 AM

Quote:

Originally Posted by Poddy

i'd recomend a Dump Valve as a BOV can cause the engine to run on a Fuel rich mixture, as the air is vented into the atmosphere

Isn't the dump valve or BOV positioned before any air/fuel mixture control units, so it wouldn't have any effect on the air/fuel mixture?

I don't plan to fit one of these useless devices to my project car, so I have no real idea where they go

**pgarner** · 24-01-2010, 02:19 AM

basically you have the version that dumps to the atmosphere, dump valve, or the ones which put the charged air back into the intake, diverter valve,. it really depends on what is fitted as standard it its set up as a diverter valve then the engine can run rough when fitted with a atmospheric dump valve as the ECU is looking for the extra air

**dpsubaru** · 24-01-2010, 04:01 AM

dont waste your money. i have a Blitz BOV sitting at home that i have never put on the Impreza. Spoke to Andy Forrest and they said dont bother changing the original unless you have some massive internal mods being done. the original one is ample.
Also, dont waste money on induction kits for the same reason, i have a Blitz Sonic which cost about 300 notes, not a bean of a difference, the original set up is best and although doesnt look as good as a shiny lump of aluminium in the engine bay it does a better job.

**BAD63R** · 24-01-2010, 11:55 AM

I had a Blitz Blow Off Vavle on the Scooby. Worked a hell of alot better than the dump valve. But in an ideal world I would go for a Recirc-Dump Valve. That way, any excess pressure released will go straight back into the system. Plus and dont hold me to this but the recirc's tend to give you less turbo lag as they allow the turbo to continue spinning when you let your foot off so when you change gear and floor it again you haven't got to wait for the turbo to spool up.

**turbonutter69** · 27-01-2010, 12:12 PM

Quote:

Originally Posted by BAD63R

Plus and dont hold me to this but the recirc's tend to give you less turbo lag as they allow the turbo to continue spinning when you let your foot off so when you change gear and floor it again you haven't got to wait for the turbo to spool up.

Thats all a dump valve does anyway.

**pgarner** · 27-01-2010, 12:45 PM

Ok a recirc valve puts slightly charged air back into the intake pipe meaning the turbo has less work to do and therefore less laggy

**Bertrum** · 28-01-2010, 01:38 AM

Tried both a BOV and dump valve on my old Scoob. Apart from sounding like a classic Chavbox it also made the car run like crap, use more fuel and attract wierdos.

Did make me laugh when it made people jump though. About all its good for.

**BAD63R** · 28-01-2010, 10:09 AM

You want sequential blow off valves, one for each piston, never get turbo lag again mate. I went in my mates Evo 3 with Evo 6 engine and that was running a nice 360bhp and had sequential valves, sounded amazing when he chagned gear and the turbo was instantly there when the accelerator was pressed

**Bertrum** · 28-01-2010, 11:59 PM

Quote:

Originally Posted by BAD63R

You want sequential blow off valves, one for each piston,

Eh? I dont get this. There is only one turbo. How can you have more than one BOV?

**MasterAuron** · 29-01-2010, 02:42 PM

Quote:

Originally Posted by BAD63R

You want sequential blow off valves, one for each piston, never get turbo lag again mate. I went in my mates Evo 3 with Evo 6 engine and that was running a nice 360bhp and had sequential valves, sounded amazing when he chagned gear and the turbo was instantly there when the accelerator was pressed

Not sure what this "one for each piston" thing means but I suggested a sequential BOV about a week ago in this thread. A sequential BOV has two valves that open one after the other. A small valve opens first, which PULLS (most DVs are push-types) the second bigger valve open.

Fitting something like this will absolutely not completely get rid of your turbo lag, in fact you'd be hard pushed to notice much of a difference lag-wise. Evo's are just like that; pull well and spool up quick from low rpms. "You want sequential blow off valves...never get turbo lag again" did make me laugh though

Bertrum, it's nothing to do with how many turbo's you've got as the device is just fitted "somewhere" along hte boost piping. It's perfectly possible to fit two or more BOV's or DV's to a single turbo car and I've seen this several times. No benefit though really. In fact, Old-git was bang on the mark when he said DV's and BOV's are pretty useless apart from the noise. I have one fitted to my car, but that's because secretly I'm still 5 and I liek the noise.

**BAD63R** · 29-01-2010, 02:46 PM

Quote:

Originally Posted by MasterAuron

Not sure what this "one for each piston" thing means but I suggested a sequential BOV about a week ago in this thread. A sequential BOV has two valves that open one after the other. A small valve opens first, which PULLS (most DVs are push-types) the second bigger valve open.

Fitting something like this will absolutely not completely get rid of your turbo lag, in fact you'd be hard pushed to notice much of a difference lag-wise. Evo's are just like that; pull well and spool up quick from low rpms. "You want sequential blow off valves...never get turbo lag again" did make me laugh though

Bertrum, it's nothing to do with how many turbo's you've got as the device is just fitted "somewhere" along hte boost piping. It's perfectly possible to fit two or more BOV's or DV's to a single turbo car and I've seen this several times. No benefit though really. In fact, Old-git was bang on the mark when he said DV's and BOV's are pretty useless apart from the noise.

Ah fantastic so I stand corrected tehn. I love this site

This is where my confusion lay. Because he has 2 turbos, he gave the impression the was one for each pistone, not 2 valves with 2 psitons each, so one BOV for each Turbo.

Nice one Master Auron

reps your way as soon as i can rep you again, says i need to spread the love around first

**MasterAuron** · 29-01-2010, 03:05 PM

Lol no favoritism eh. Happy to clear that up for you. I think the bottom line is, unless you want the noise just stick with the standard or an aftermarket re-circ as these will be marginally better performance-wise but imo the difference is negligable.

Also, some cars just don't like DV/BOV's altogether and can cause dodgy idling/stalling etc (such as single piston DV's on cars with AFMs)