Ive got a saff cossie 4x4 its got a stage 2 chip with greens and a 3 bar map sensor. My car has got a forge dump valve. Ive had this daft running fault on my car and a lad i know reckons the dump valve was leaking cause when you put your hands round the dump valve you could just to say hear it. He took the dump valve off and the fault i have is still there. Is it safe to run the engine without the dump valve. I quiet like the sound of the turbo chatter compared to the noise of the dump valve. So is it safe to run the engine without the dump valve.

 

T3 or T34, either are fine without

 

would the actuator get knackered more though inc the turbo, cause my hose running from the inlet plenuim to the dump valve came off the other day. no dump valve acton, but loads of lovely wastegate chatter which sounded awsome.

 

the noise isnt wastegate chatter, its boosted air going the wrong way through your turbo, which can be rotating at 100,000rpm....still think its a nice sound?

i would never run a turbocharged car without a dump valve, i have seen a broken shaft.

 

Its on a standard T3 turbo.I was thinking about putting it back on to be honest even though the sound of the chatter is mint.

 

even if your dump valve is leaking it wont cause actual running faults, unless its leaking on the small vac pipe side....the dump valve is before the throttle body....

if it leaks you just have to work the turbocharger harder to acheive your desired plenum pressure

 

now mate still there then have to check a few things when your back through and do a proper leack check if its still there it wasnt down to dv but it was defo leaking

its a diafram dv and they aint the best if you still want a dv ill swap you for a piston one if you want

 

it has a problem that means it keeps on throttle when you let off but not for a large amount of time

just a little then drops off ill check it over properly next time he is down but id sugest a senssor set and make sure the rest of it is ok

 

sticky iscv maybe?

 

didnt get chance to clean it the other night but the best way to do it is take it apart give it a thorough cleaning then put it back together and lube it with brake fluid i find works realy well as lube like wd40 dries out tooo quick

 

wd40 is the worst thing to use, when the solvent evaporates your left with grease!

thin oil, like 3 in one is best imo.

 

Thanks Jacko your a star.I just like my car to be right.I will have to get some money and get a full sensor kit off you.I just dont like asking you Jacko cause your a busy man.I just want my car to be right just like the rest of us.Cossies arnt getting any younger.

 

ill just give you a set and you can pay when you have it mate

 

I dont like borrowing things i would rather pay for them first.But thank you.I will see mark and see if he wants to pop down another night thats if you will still be there after 6.Or i could pop down at the weekend.

 

just come get a set you big girl iv got loads in and ill be there till around 10 11 tomorow night

 

As long as your sure.

 

corse mate

 

cheers mate i appreciate it, i dont finish work till 6 so will probs get to yours about 7ish.

 

I would never run without a DV either, you have eliminated the dv as the cause of the
noise, it is no doubt just general air moving noise that was heard.
What precisely is the runninmg fault ?
You may find you have a heap of lag without a dv as well.
tabetha

 

The old DV debate again, personally I would never run my car without one.

The sound is NOT wastegate chatter as been mentioned it's simply boost pressure being forced back through the system from the front of your butterfly when closed until it finds a way out.

Normally your DV takes care of this and opens to 'Dump' the pressure to atmosphere but without it will go back till it can get out through the turbo.

'Chatter' as it is nick named is actually your turbo stalling, the sound is the air being forced back through the turbo blades and is not good for anything.

The car when new was also fitted with a DV.

Kind regards,

Martin.

 

The fault is when its a cold day and i start my car up and drive it the revs feel as if they are sticking on and you can take your foot of the throttle pedal and the car will drive itself for a bit.It just feels like the choke is coming on and off.I went out in it last night,it was a nice night and not cold.It didnt do it last night it drove really nice.Like i said it only does it when its cold,im thinking it might be the ISCV sticking.

 

A lot more likely to be iscv sticking.
tabetha

 

I will take it out and give it a clean. What is the best way to clean and lub them.

 

i've got a bailey recurculator sitting in the shed if u want one.........hate the fookin' things

 

i have never understood why people say you will siffer more lag without a dump valve. Surely dumping a boost pipe full of air out into the atmosphere will create more lag as you then have to fill it up again the next time you plant your foot down. With no dump valve there is no where for that air to go therefore the boost pipe doesnt need re-filling so to speak? I found my cossie more repsonsive through the gears without one tbh

Plus i ran my t34 at 2.5 bar peak without a dump valve and all was ok

Now i use a gt30 i have no choice but to use one. Isnt as annoying as i thought it would be

 

Without a DV (like I run on T34) you can keep some of the pressure in the pipes & intercooler, and the turbo slows down a bit/lot... or run with DV, you lose the pressure in the pipes & intercooler, but the turbo slows down much less.

So which causes more lag? Loss of pressurised air, or loss of turbine speed?

And shall we factor in the size of the intercooler? The size of the turbo?

All interesting stuff! I run without DV because they sound gay.

 

I doubt your going to notice much difference in lag by running a with/without a dump valve.

I run a dump valve now, never used to but my turbo is on its way out and just looking at how it works makes you realise why it's worthwhile in a way

 

Though the thread's not intended as a debate on lag with or without, my experience is that I get more lag without, much less with a dump valve fitted.

The lag stems from the compressed air having nowhere to go with the butterfly shut, hence, stalling the turbine. Try putting a food mixer into solid chocolate and see if the beaters spin faster than when they're in the air. Ever stall an engine when you snap the clutch up too quick when pulling away? Did it make the car go faster? Methinks not. The turbo stalls, air goes back the other way, and when you open the throttle wide enough to spin it up again it spools up only to be stalled when you let off by blocking the compressed air's path again. Personally I love having my own pigeon under the bonnet, but I just can't live with the lazy boost.

If you drive at full throttle (or even mildly wide throttle) all the time, you probably won't notice a difference, particularly with big boost, ie 2 bar. I know I certainly have to wait longer for the boost to build up, particularly on part or light throttle with my weeny T3 at 1 bar.

 

I prefer the noise without the D/V + when i got my car mapped by Karl @ NMS he said i dont have to run a D/V and with his knoweldge i aint arguing with that

btw its a t34.48 spiking 30 psi, coming to 26 and holding 20psi at top end if that helps/makes sense to anyone

reiss k

 

Karl is indeedy a clever chap, but he didn't say you couldn't.
This has got me so intrigued now I am going out in the car later and try both ways, though personally I don't like chatter.
Very interesting to hear others views/experiences though.
tabetha

 

I went out in my car again last night and it was a warm night and the fault that i have been complaining about didnt happen.

 

i dont run a dv, i have a t34,

i have run 1 before, i sufferd with turbo stall even with a dv, i will prob go back to running 1 when the cars back on the road

 

Ive seen your resto mate i will keep an eye on it.I will clean my iscv out this weekend and lub it up.What is the best way to do it.Shall i leave it to soak for a few hours to lub it or just put some lub on and then refit it.Ive been told to use brake fluid to lub it.

 

cheers fella, brake cleaners fine, carb cleaners always good as well, as to what to lub it with im not to sure,

 

I use pure silicone spray, but if none to hand furniture polish often has silicone in it.
tabetha