James is right, they do have one already.

You can hear it very prominently by changing your air box to a cone filter. Recirc ones are even louder.

I have to say, I am getting a touch annoyed with the sound of mine.

I am thinking of doing away with it all together.

The dump valve is there to prevent the turbo from stalling as pressurised air tries to flow back through it, when you close the throttle and the air has nowhere else to go.

 

Dump valves don't improve performance merely relieve excess pressures on the turbo and hosing theoretically giving them a longer life. I have one fitted to mine and occasionally the noise gets on my T1TS!!!

 

Now on to my next question,

"Will it harm the motor if I put an atmospheric dump valve in a standard motor?"

Advice will be appreciated.

 

Dump Valves that is!

Tell me someone, does these "dump valves" improve performance or improve the health of a car?

I know that some cars don't like dump valves and some do.

I just want to know what will happen if I put one in my standard Turbo (apart from the whooooshing noises ).

 

I "think" they are generally added when the boost has been upped!? Anyone?!

 

Imprezas already have a dump valve. Its a recirculating one, so quieter.

You can put a dump to Atmosphere in an Impreza, but these are known to cause overfuelling.


James.

 

Gordon,

Not sure about harming your motor, but would probably give a dealer a get out on any warranty claim

A guy down the road from me has one on his MY98 and I think it sounds crap. Much better noises come from ScoobySport and ProDrive exhausts

Yex

 

Gordon, I'm not sure if it will harm it, but the mpg will be hammered. By venting to atmos. you fool one of the meters, making it run VERY rich.

If I remember correctly Blowdog had one, and was getting crap mpg. But very nice flames (4 foot)

Dan

 

Dump valves are THE single most con in the performance tuning industry. They will never give more power. The vent to atmos ones are a total pile of poo. And there have been instances when these CAN damage the engine, by sucking in crap straight into the plennum......not good (though the newer piston type ones are better).

As already mentioned recirculating ones do a specfic job (as has already been mentioned......but this is not the reason for installation on standard cars). Not sure about the standards of scooby turbo's, but my Escort Cossie T34 turbo doesnt need a dump valve (either atmos or re-circ) and thats pushing 24psi boost. This turbo stall only happens in extreme conditions and even then it has to happen like plenty of times to do any damage. The main reason why a re-circ is installed on most production turbo cars is because of the issue of lag. In theory if the turbo is kept spinning between gear changes, the response is better when slapping the loud pedal after a gear change. Simple physics really. But don't forget, if you replace this with a vent to atmos one.......you can forget this benefit!!!!

Vent to atmos dumpers can also leak boost pressure and lose response.

My vent to atmos dumper is now off and the car holds boost much better and feels more responsive. I am aware that future power upgrades will require me to have a dumper (but for the reasons mentioned), but that is only when I reach circa 36psi boost

If you want a noise get a vent to atmos dumper......cause for our kind of power levels, thats ALL it's gonna do!!!!!!!

Regards,
Shaun.

 

I disagree, I had one on my Rover 800 Vitesse, 2.0 turbo and apart from the noise, I had much faster in gear response between gear changes and the engine was much more tractable because of it.

I removed it before I sold the car, and noticed a big drop of in acceleration.

Jasong

 

Jason,
This board is all about peoples different opinions!

You never said whether you used a vent to atmos one, but if you did, could you explain how venting air to atmosphere will give you better acceleration??

If they do what you think/say they do, why are they not incorporated into leading racing cars for WRC etc etc??

The Rover turbo engine has a nice little black recirculating dump valve already on it. Did you leave that on or take it off when fitting your new dump valve. Either way it's irrelevant, cause you would only be doing exactly the same as what the standard re-circ one did......but less effeciently with a vent to atmos one!!??

The recirculating ones (the standard production ones or after market ones), do have a purpose in CERTAIN applications..............the vent to atmosphere ones are a TOTAL waste of time, except for the nice/annoying noise.......the re-circ ones are much more effecient and safer.

The general concensus is, is that if you stick ANY so called performance enhancer on a car your brain automatically expects improvements and sometime see's what is not there.

 

i have dumpvalves on my r33 gtr. **** performance, they sound immense
time your gearchange, drive past the girlies, and give 'em a quick blast pimp daddy

shaun,
you seem very knowledgeable about cossies. that is one big psi figure there
just how quick are cossies? i always liked the sapphire ones, isnt that what spender drove? cool car

[This message has been edited by turbo spudgun (edited 15 August 2001).]

 

I had an air to atmosphere DV, and it was not only me that noticed the difference.

It removes lag on the turbo by getting rid of back pressure causing the turbo to slow down, and I am of the understanding that all turbo charged rally cars do run these DV's.

I understand that you always want to believe that something makes a difference, and in some cases you con yourself into believing that it has made an improvement. I have been into cars, both standard and performance and rallying for long enough to be able to actually tell if some thing makes a difference or not.

I also know that the Rover engines do have a recirc valve, but I cannot explain why there was such a difference, but there was.

Jason

Ps All in good spirit

 

Most pukka rally cars run antilag systems, which doesn't work very well with BOV's.

 

Defaecating in Public is illegal unless you live in Daventry, if you are caught short needing a wee and get caught by the police you can claim "renal stones" as mitigation under a law from 1864.

I wish I could claim my lapses of judgement over the last year

Keep your purses shut boys!

 

Gordon
i have the newer Bailey Evo D/V (atmos sort/ Pison thingie lol) wot ever it is
on a MY97 Turbo
sounds wicked!!! but i have noticed a small amount of drop in MPH, but So! its sounds the bizzzz.
i haven't noticed any other problem!


Phil

 

IMO - you'll only benefit from a dump valve when running big boost. Most people use them with a poor understanding of what they do and when to use them. Depending on what model you use and how you set it up, they can be more of a hindrence than a help, i.e: they will suck unfiltered air and can give you problems. They can also cause the engine to hunt at idle.

 

jeez.

here we go again!

we need a dump valve newbie FAQ area.

shaun, you got one thing wrong m8.

recirculating dump valves dont give any advantage over vent to air when it comes to lag. They are both pants and will increase lag over a car without a BOV.

Look in the drivetrain area. Thats where this should be anyway! Its been covered about 16,000,000 times.

 

I went to buy some alloys from some guy with an MY2000. He had fitted a noisy dump valve. I asked him why he had spent £300 on this, and what the advantages were. He replied "cos it makes a pssssshhhht noise innit" He also told me he was considering having the prodrive suspension kit fitted, however he said "It's a rip off, all that money just to make my car look 1 inch lower !"

Me, I wouldn't spend £300 to get a pssssshhhht noise and sound like a divvy.

 

LOL gazzer

 

Hey Gordon

Long time no see. I have a forge dump to atmos one on my car and i love the sound of it. Havent noticed any drop in MPG either. As for any damage it does....i dont care

Ian

 

James and Danny,

Could you please explain to me how a vent to atmos valve will dramatically reduce the mpg figure of a Scooby.

Both the standard recirculating and vent to atmos dump valve are shut when throttle is applied so please tell me how the vent to atmso makes the slightest bit of difference to the running of the car when under load.

The way I see it is that the only time the car overfuels is when you throttle off and the MAF sensor is programmed to expect X amount of air to be recirculated into the system by the standard dv and so fuels appropriatly. A vent to atmos valve doesnt recirculate this air and so the car overfuels as a result, causing pops, bangs and big flames on the over run. At no point, however, does the car INCREASE the fueling level.

Re-apply the throttle and the car again runs as with the standard valve so please explain how the mpg figures fall through the floor.

All Scoobys come with a dv fitted as standard, the only advantages of an after market one is that they are able to stay closed under greater boost levels and, if you fit a vent to atmos version, go WOOOOOOOOOOSH!

I believe that most turbo cars are fitted with a recirculating dv as standard to eliminate the noise caused when you throttle off and the pressure in the intake system bounces off the closed throttle plate and hits the spinning turbo blades causing a loud chattering sound. You will get LESS lag if you DONT run a dump valve as the pressure is retained within the system.

The only dump valve that will cause a turbo system to loose boost is a cr@p or knackered one!

And Ill think youll find that the majority of turbo charged rally cars DONT run a dump valve. My friend rally a Sapp Cossy running 32psi of boost and he doesnt know any rally boys who have a dump valve fitted, be it recirculating or otherwise.

So there!!

Bren

 

like i say, its all been covered in detail in drivetrain. do a search, you'll find thousands of pages on the damn things.

 

What exactly is big boost? On a scoob.
Banzai did a Scoob v Evo rolling road day.
Evo's were getting 300+ Scoobs got 270+.
If the engine on a UK scoob is really as weak as some say, if you have a PPP [or Link], decat exhaust and aftermarket filterare you then going toward the limit of the engine? Will a dump valve then be a worthwhile/necessary addition?
You got me stumped.
Me. I ike the noise