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Dump valve, good or bad for the turbo?

carrmrc96

carrmrc96

Car  Roadster Coupe
Im gonna order an R26 soon and might fit a dump valve, are these good or bad for the turbo? some people say there good cos they reduce turbo lag while others say there bad cos they stall the turbo, whats the real answer? surley if they was bad they wouldnt make them in the 1st place.
 
depends if you need it or not. the blow off valve helps keep the air flowing through the turbo, with no back pressure so that it doesnt stall.
 
are dump valves and blow off valves the same thing? would i need to fit a blanking plate or would just a dump valve be ok?
 
yeh it comes wiv a recirc valve but u cant hear it. i aint after a loud noise, just a quiet subtle 1.
 
It should be fine aslong as you get a double piston (IIRC) one, I had a Forge one on my Fiat Coupe. Just replaced the standard plasic Bosch one and put a cut off bit of broom handle in the bit where the old one recirculated.

The only difference between the recirculating type and the direct to air type in this case is that it doesnt dump the air back into the air intake system.
 
yeh i suppose they r, im aint sure wether 2 get 1 or not. but yeh they r a bit chav really when u think bout it. well as long as the exhaust has some grunt and i can here the turbo spool up like my old golf GT TDi then i'd b happy.
 
Fine, im going to say that changing the exhaust to get a different note is gay aswell then, after all it is more or less the same thing.

You are not making the car do anything other than what it is supposed to do, all you are doing is changing how loud the noise is.

With a standard recirculating one you would still beable to hear it is you had short induction tract and a fairly free flowing airfilter anyway.

If you fit a kit which makes the noise on a NA car then yes, that is extreemly retarded, but not on a car which is SUPPOSED to do that
 
LOL. i dont know what to do! im 50/50 on wether to fit the dump valve. Does the dump valve make a noise on every gear change with the same loudness, or does it get louder at higher revs?
 
recirculating ones are supposed to be better as they (maybe) keep the turbo going a little bit, cause of the recirculating blow off. Open one does'nt. (and are gay)
 
A dump valve will prolong the life of a turbo but if you have one that vents to the atmosphere they are pretty crap.If it has a recirculating one as standard and your not upping the boost leave it alone.
 
Just to point out your car will already have a dump valve fitted as standard but its a re-circulating type. You want to fit an atmospheric type ie it vents the gas into the 'atmosphere' hence you get that whoosh.

If your car has a turbo don't see how its chav??
 
well i'll test drive the R26 next week. if the original recirc valve is loud enough 4 me then i'll keep it standard. if not i might get the k-tec dump valve.
 
Danlp6 said:
^^ not as such

very very rarely do you ever hear the wastegate. what is usually heard is the turbine stalling.
Click to expand...

When i had my five if you were giving it beans and came out of the throttle you could hear the wastegate big time.
 
aye you can on the 5's but it wont be fluttering onless there is something wrong. or you have en external wastegate. but then again even with the rally cars etc they get compressor surge rather than wastegate chatter.
 
carrmrc96 said:
well i'll test drive the R26 next week. if the original recirc valve is loud enough 4 me then i'll keep it standard. if not i might get the k-tec dump valve.
Click to expand...
A re-circulating dump valve won't make any noticeable noise as it doesn't dump to air (as atmospheric ones do)

I'd just leave it as it is tbh.
 
Leave it as std untill you get some miles under your belt!

Give it 1000 miles or so before you start modding/tuning to loosen up and chances are the car will have a few niggles that need to be sorted at the dealers so warrenty issues come in to play!


leon
 
There seems to be a lot of misinformation/hearsay in this thread. I hope the following helps the OP make an informed decision.

1. Blow off valves (BOV's) and dump valves are the same thing. They're just the different names different countries give them.
2. The R26 will come with a re-circulating BOV as standard, as will all turbo cars.
3. The BOV's sole job is to divert any unused, compressed charge, from the turbo, that's in the intake track when the throttle plate(s) are closed. The idea behind this is to stop the turbo from stalling, theoretically extending it's life. And, in doing so, reducing the time it takes to spool up the turbo again, reducing 'lag'.
Obviously, a re-circulating BOV will do just that, re-circulate the un-used charge, back into the intake system, normally into the air box so that it can expand again.
A vent to atmosphere (VTA) BOV will again, do just that. Vent the unused charge into the air, making the whoosh or whatever sound.
If you don't use a BOV, you wll stall the turbo between gear changes. Although with modern turbo's, it's very unlikely to reduce their life by any large margin, it will increase the turbo lag. This will of course make the cars acceleration worse. It will also cause what's known as compressor surge. This is the tssh tssh tssh sound you may hear on some turbo cars. This is not wastegate chatter as, there is no such thing. If you have an adjustable BOV, you can purposely make this noise, if it floats your boat.
The Prodrive P2 also makes this noise but, because of the intake system and turbo it uses, it sounds more high pitched.

If the R26 uses a MAF or AFM to measure intake air capacity, you might have problems fitting a VTA BOV as, the engine will actually see less air than the MAF is telling it so, more fuel will be dumped in and, the car might stall etc...
This isn't always the case though. I use a VTA BOV on my Pulsar and that uses a MAF. It never stalls but, I'd suspect it does run quite rich on high load gear changes.
If the car uses a MAP sensor to instruct the ecu as to how much air it's ingested, you'll be totally fine.
If you are keeping the car running stock boost levels, the stock BOV will be fine. If you're going to up the boost or, just like the noise, I'd personally recommend a 'pull' type BOV, that uses a piston and not a diaphragm. These work differently to most BOV's as, they pull the piston to vent and not push it. This gives them very good leakage resistance and they'll stay closed at idle. Practically eliminating idle stalling. Something like the HKS SSQV would be ideal although, don't buy a authentic one as, they're very overpriced. Hunt around on eBay for a replica. They're exactly (yes, exactly. I've seen them in pieces) the same thing at around 1/4 the price.

I hope that's answered your question ?!
As you can see, there's no good or bad about them really, it's just what you want out of it, at the end of the day.

Paul
 
get a blitz super blow off valve. you can change nozzles for different sounds. you can even get one that sounds like a ducks quack!
 
The R26 will come with a re-circulating BOV as standard, as will all turbo cars.
If you don't use a BOV, you wll stall the turbo between gear changes. Although with modern turbo's, it's very unlikely to reduce their life by any large margin, it will increase the turbo lag. This will of course make the cars acceleration worse. It will also cause what's known as compressor surge. This is the tssh tssh tssh sound you may hear on some turbo cars. This is not wastegate chatter as, there is no such thing.
Click to expand...

All Turbo cars do not come with any type of dump/re-circ valves, although far more common place now.

Modern turbo's are more susceptible to damage. The old T designated garrets will take s**t loads of abuse compared to a modern GT series.

Acceleration will not be improved, it will infact be worsened as the turbo will spool up quicker than it will replenish the lost pressure from dumping.
 
the compressor stall that everybody including myself loves the sound of is actually what does the damage- but you only start encountering problems running 2bar upwards they saw the turbine shaft twists on itself due to stalling on built up pressure.
never actually seen it though.
dump valves do nothing but leak boost and cause problems with airflow metering.
 
I have an R26 and have so far tried 2 different dump valves - personally love having an extra bit of sound from the car.

The standard exhaust is almost silent unfortunately so personally I removed the back box for a bit more noise and to make it more free flowing - currently at 237bhp (10bhp over manufacturers quote)
 
Thanx for info guys, well i think i'll leave me car do some miles and then choose wether or not to mod the car. I may even like the sound of it standard. time will tell. gonna order the car next week but theres something like a 8-12 week waiting peroid b4 it comes which sucks.
 
Paul J said:
Modern turbo's are more susceptible to damage. The old T designated garrets will take s**t loads of abuse compared to a modern GT series.
Click to expand...
Wrong.

Modern turbo design is far superior to the old days. Better tolerances and materials are used. You just have to look at modern car service intervals to see this.

And the 'T' series Garrett turbos are still used in modern cars. The 'GT' series turbos are not used, in general on production turbo cars due to their cost.
The only real difference between the two is that the GT series turbo's use roller/ball bearing cores which give improved spool up. Obviously the A/R's and wheel sizes etc may be different but, that will be the case with any change in turbo design. The designer will make the most of the given turbo's characteristics.

Paul J said:
Acceleration will not be improved, it will infact be worsened as the turbo will spool up quicker than it will replenish the lost pressure from dumping.
Click to expand...
And wrong again.

The fundamental idea behind a BOV is to release the pressurised charge from the inlet track, when the throttle plate(s) are closed. Thereby, keeping the turbine spinning, so, it will be back up to boost in as little time as possible. There will still be charge in the intake track, the BOV will just release the charge above atmospheric pressure.

Without a BOV, the turbine will stall or, at the very best, be slowed. So, the turbine components inertia will need to be overcome, to spin the turbine back up, to make boost. This will increase lag.

The majority of turbo lag is caused by the inertia properties of the turbos spinning parts. It will always be shifting air but, the pressure of that air (amount of boost), is directly related to how fast the turbo is spinning or, whether it is spooled up or not.

A lot of turbo car owners perceive the response of the turbo to be better without a BOV. This is not actually the case but, because of the lag and the way the boost comes back in a big hit, as opposed to a smooth transition and the turbo already being up to boost (or there abouts), with the turbine still spinning on a BOV equipped car, it will feel more powerful.
 
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