This is apparently not reccomended on bigger turbos, why exactly is this? Excuse my ignorance!

I have heard that bigger turbos W/O DV's are more prone to early failure, does the bigger turbo generate more force when it stalls, is the shaft design on a T4 the same as a smaller turbo? Or simply because the larger turbo is running at higher performance level so the shock load on the bearings is greater when it stalls?

Although I am keen to hear from people who have run a T4 for a long time without a DV and have had no issues, this does not really answer the question in a technical manner. Cheers!

 

Never heard it before, but can't see why not.

It actually will be worse, as for a given boost pressure, the larger turbo will contain more oxygen.

Martin

 

Thanks, I was hoping you'd just lie and say it would be fine

 

Ive heard the boost pressure has nowhere to go so it stalls the turbine and starts to damage it.I dont know if this is true.

Why dont you want a dump valve fitted is it cause you think there chavvy.

 

Won't the compressor wheel shear the shaft as it violently stalls ?
You can run a quite dumper

 

Can't you run a recirc instead?

 

Doesn't it depend on the amount of boost pressure you run?

 

ive never, ever ran under 30psi, ran a dump valve, or any sort of faggot valve,

always ran Garrett T4 (RS200, RS500 and other types, 4 of them)

Turbonetics T61 at 40ish PSI

never, ever had a failure from broken shaft

 

Faggot valve? They do serve a purpose

 

if i want my car to sound like a bus i would get the fucking bus!

 

Copied out of fast ford mag.

 

Never believe what you read on forums and magazines.

 

they are almost a neccesity on some of the gt range of turbos due to thin relatively weak shafts and plastic ballbearing cages but "t" series turbos are man enough to run without

 

I've never owned a car long enough to know

 

Beat me to it

 

Cheers. I've had issues in the past destroying turbos, it always seems to happen when I take the dump valves off. I would assume that the failure is due to stall, but together with a knackered bearing, so you have excess play in the shaft, then bang! So in essence the route casue is not the DV, but the worn bearing, the failure only happens earlier becuse it's stalling?

So at a guess off the top off my head if you had a new turbo with a good bearing, it wouldn't matter about running without a DV?

 

I love the sound of compressor stall, and I've run three completely different turbo cars without dumpvalves..... but I've had complete failure on each of them!

T34 at 24psi on my Cossie, CR Turbos recently rebuilt that for me and it needed a complete new core. The turbo had only done around 6000 miles since its last rebuild.
T3 on my Alfa Romeo 155 Q4 at under 20psi snapped the shaft at the Nurburgring. I've still got the turbo where you can look inside and see the impeller jammed the wrong way against the housing!
The last 15T on my old Volvo 850 T5 at just over a BAR failed for the new owner not long after I sold it. Don't know the whole story, but I'm guessing it's similar!

I'm now sadly a convert to sneezevalves

 

It's possible to bend the shaft as its only 3/16 thick
You can get away with it but it will break eventually

 

Lucky boy!

My advice peeps get your faggot valves well and truely on there

 

Cheers lads, I forgot to mention that I also refer to them as fag valves seems to be the common name for them now. I wouldn't run one unless I had to, so looks like i'll have to leave it on.

 

Run recirc like mine.. I hate the noise, I miss a bit of chatter so have to make up for it with ALS lol!

 

I can still make my saff chatter with the dump valve on. If im flooring the car like say on the motor way and I back of the throttle slowly it will chatter then.

 

Great minds think alike. Well I wouldnt really say I have a great mind lol.

 

I fucking HATE the sound of dump valves, and LOVE chatter, but let's cut the BS and have some facts here.

I've personally seen, in the flesh, as it happened, at least 2 (possibly more, can't remember) RS500 T4s snap shafts, and both were with no dump valves. Countless others in the same situations with no turbos dying.

MOST other turbos cope way better without one, I've ran many cars at 1.5-2bar with no DV and no issue. I think quite possibly the RS500 T4 is a very big compressor for a very thin shaft, so it doesn't cope as well.

You might not realise, but while the air stalls without a dump valve, the shaft speeds up. This is why the thing about DVs helping response is total BS, but they can indeed help turbos live (honest, sounds wrong, but tis true).

Also, DVs with very strong springs that chatter THEN dump are fairly useless, as tbh the damage is already done then.

 

Stav??

 

Was thinking the same thing!

 

Tony must have a good view on this ?

 

My Tuner Spec's my engine so if I open the bonnet & see a DV its because its required. Too many non-experts on here giving advice as is always the case.
My advice is never listen to advice on an internet Forum.

When I used a T4 about 700 years ago it had a DV fitted so it was required we ran 42psi back then. Another bit of advice you must not listen to is fit a DV & ditch the T4 it was outdated in about 1990.

 

Looks like it's staying on.
I do agree about the internet forum advice in most cases, but it's also nice to research these things for yourself from time to time and get input from more than one person. I searched for info on this topic already and couldn't find anything so hopefully this will help someone else if they are considering it.

 

I disagree, my t4 suits my engine better than any gt series turbo would due to BP
Horses for courses rod

 

I just wanted a T4 car, the same reason as I wanted a saph, obviously there are far better options....