dump valve on my hawkeye WRX PPP
 

Thought I would post this as a 'final thought' on dump valves (as far as i am concerned anyway)... having fitted a turbosmart supersonic VTA at Xmas, i was getting 'lumpy' performance, which did get better the softer i had it set, but still not great. I recently fitted a boost gauge and was shocked to see it only boosting to around 0.6bar. So i finally decided to go back to the original recirculating valve - OMG!!!!!!!!!!! It's like a different car, i must have forgotten what the performance was like and been kidding myself 'cause i love the whoosh sounds so much... But what the hell - I'll live without the noise and take the performance thanks very much! Boosting back to 1.1 bar now, running smoothly, happy days!

Al i need to do now is persuade my missus to lean out of the window and make 'PSSSSSSHHHHHH' noises every time i change gear.....

So - in conclusion - yes all you gurus on here that laugh at after-market BOV's... you are correct..... I bow down to your knowledge, oh great and hairy smart-ar$es....

I guess you Live and learn!

laterz, Chris.

Absolutely right .. I remember years ago at a Rolling Road Meet I was at my 02 STi PPP was going on after 2 04 and 05 STis both fitted with Dump Valves , 1 with PPP + 1 without , both were at least 20 - 30 bhp down and mine was bang-on 299.4bhp standard :) The guy running the rolling road explained that it was the dump valves that caused this and should only be used if mapped with 1 fitted.

Steve

Don't have one on my Hatch but had a HKS SSQV on my old Hawk WRX and run perfectly.

I have been running my car for the last 3 weeks with the standard recirculating valve back on ,and i can HONESTLY say that after having a baileys dump valve on for2,a forge dumpvalve on for 3 months and the current blitz on for 4 months,the difference by reverting back to the std one is amazing.
The baileys dv - caused erratic idling on my car from cold start up,and especially when easing off after boost,tried a softer spring,but still no joy,was also the cheapest looking with a small plastic elbow to join your vacume hose.This was also the most annoying as it would go off at low revs and drove me nuts on the motorway.

The forge dv - appeared to be better made than the baileys and for the first 4 weeks seemed ok ,then started to get erratic idling mainly at lights 750 -1100 rpm when car was warm.Took dump valve apart and removed the film of grease in the plunger,cleaned inside and put it back together still no better,this dv would vta after 3000 rpm which was ok ,but between shifts it was quite jerky and was not smooth at all.

The blitz bov -After not being happy with the previous dumpvalves i bought this off a member of midland scoobies,1st thing i noticed is it a lot heavier than the othe 2 dv's,also the flange that bolts to the intercooler is slightly bigger than the other 2,and it appeared to be better made than the previous 2 .This came with a sus filter so you could change the sound ,but in all fairness all the filter did was block the smaller of the vta ports so the car made no noise at low revs.This when fitted also caused erratic idling ,but after a quick call to blitz uk i adjusted the screw on top of the valve till the idling was set and the plunger was just opening.Dispite being the most expensive of the 3 dv's the blitz was the one with the simplest components,aluminium body,spring ,plunger,adjustment screw.

I have put the standard recirc back on and had it on for 3 weeks now ,and can honestly say the car runs much much better,No idling issues at all 1400 rpm from cold ,then settles down to 750 rpm at idle.When changing gears the pick up is smooth and car does not hesitate /stutter before back on the power. The main thing i want to add is that my recirc valve is the original one that came with the car and dispite being 10 years old and covered 130k it is still performing impeccably.Like the o/p i suffered with car boosting to0.7 bar max,had the car mapped 8 days ago with original recirc on ,car pulls 1.3 bar with no issues at all.

I would lastly like to say these are the results that i found using the dv's on my MY99 impreza, there are people who have used all 3 of these valves and had no running issues at all - but for me now the recirculating valve will stay on the car while the car seems to be running as well as it is

I love all these comments about d/v's being OK on some poster's cars. How do they KNOW?

Did not test numbers on a rolling road road or take engine apart to see if any internal damage or wear, did however:

By a brand new car and drive with std DV fitted.
Fitted HKS DV and continued to drive, no noticable loss/increase in performance
Removed HKS DV prior to seeling car, drove around some more and again did not notice any change in performance.

MY conclusion on MY car was that fitting an after market DV gave me a Pshhhh with no loss/gain in performace.

Could it be that that newage cars ECU's are clever enough to compensate for an after market DV and Classics struggle???

hmmmm. Arronb, not sure about the logic there as my car is a 2007 Hawkeye. Could it be the TD04 turbo can't cope with the pressure but bigger blowers can? I assume the standard re-circulator works better as it keeps the turbo spooling using the recirculated gas? Someone who knows please tell me!

Like I said, I knew they were not ok on my car due to the problems posted above, but as the previous poster has said he had no problems using one at all. Most of the mappers on hear will tell you that there is nothing to be gained by fitting one - only a noise.however it does not stop them from being able to map the car because of the dv.

Mine was on a 2006 Hawk 2.5L WRX

If anyone want to know more do a search, there and pages and pages on DV's, pro's, con's and people just wanting to argue the toss!!

Subject must come up every week I'm sure, think I did read there was no point changing a vent to air type though if your running less than 400bhp.

i fitted a forge dump valve to my 99 uk classic a month ago and have had no issues or difference in performance at all but with the turbo smart adjustable dv,s i have heard you need to remap your car to accept them and the dump valve itself needs setting correctly too. im sure if you speak to a reputable tuner they will also tell you this is the case.

Just noise.

It will hamper the remap if the dump valve is leaking boost which a lot of aftermarket ones do (baileys in particular)

I have one fitted to my gb270 and when put on the rollers on saturday it ran fine 275/344

hmmm, lots of good answers here - cheers guys - i reckon the mapping thing is the issue really. Not wanting to go down that route (cost) really so i'm now without the old 'pssshhhhtttt'... shame.

PS - anyone want to buy a good condition Turbosmart Supersonic 'sleeper' series (black finish)!!!!!!!!!!!!!!!!!!!!!!!! Only £100 to any of you lot.

lol.

Just buy one that has a stiff enough spring rating. You then shouldn't have any issue with not reaching boost, lumpy idle etc. You will get a rich condition when you lift off, but that's no great issue.

Not really. The fundamental issue, especially on newage cars, is that from an engine efficiency point of view the standard recirculating valve is simply the best performing one you can get for the car. As such, at best, anything you replace it with can only be "just as good", and anything that vents to atmosphere is going to confuse the ECU.

As has been said if you can't maintain target boost with an aftermarket valve, it probably needs a stronger spring, but if you go too far in that direction, the valve won't open when the ECU (or turbo) expects and you end up with pulsing effects through the induction tract - which confuses the airflow sensor and stresses the turbo.

I had my car mapped with one fitted, would there be any issues refitting the standard item? :wonder: