fiestaturbo.com

by **beanyfrst** on Thu Mar 25, 2004 3:21 am

[ERRR] is better for the performance (acceleration) and also better for engine and turbo.

by **Tams** on Thu Mar 25, 2004 9:24 am

dump valves dont dont nothing for performance but sound "good " to some people if you like that sort of attention past the bus stops outside a local college or something

by **AdrianFRST** on Thu Mar 25, 2004 9:30 am

Tams :dump valves dont dont nothing for performance

Can you explain why you think they don't do anything for performance?

Just curious, because people seem to have a strong opinion based on hearsay, without actually knowing what's happening inside the turbo during throttle lift off.

by **Tams** on Thu Mar 25, 2004 9:42 am

all they do is boost the presure outlet , an gently spins down the turbo after takin foot of accelerator its ,long to explain but if ur so know all tell me what it does perform wise ? for £60+ is there any point ?

by **xrsi** on Thu Mar 25, 2004 10:38 am

the chatter that you get without a dumpvalve is the turbo blades stalling as the air is forced from the throttle butterfly back to the turbo, stalling the blades! this increases the lag as it has to get them spinning back in the right direction!

with a dump vlave they dont stall so quicker spool up!

oh and if running serious boost less chance of blowing ur fins off ur turbo!

by **MIK3Y** on Thu Mar 25, 2004 11:44 am

Wrong, chatter is the wastegate snapping open and shut.

A FRST does feel more responsive with-out a dump valve but i use one to look after my turbo as it can't be gud if the blades and the bearing/spindle get forced back the other way when letting off IMO.

Strange things dump valves as they are surpose to reduce lag but thats just not the chase and i don't quiet know why. :-s

by **stevee** on Thu Mar 25, 2004 12:27 pm

Dump valves are used to slowly spin down the turbo, (releases pressure in the system) this way it dont damage the inlet and outlet blades and dont force a feed back, this way u here the turbo chooo noise each time u lift the accelerator. valve is only active when the accelerator is lifted...

by **MIK3Y** on Thu Mar 25, 2004 12:37 pm

I run mine with a Forge Group A to prolong the life of the turbo but i will run with-out when i 1/4 mile it as every1 with experiance has recommended that.

by **AdrianFRST** on Thu Mar 25, 2004 1:01 pm

MIK3Y :Wrong, chatter is the wastegate snapping open and shut.

WRONG

Chatter is the air reverberating off the turbo blades when the throttle is closed.

by **Tams** on Thu Mar 25, 2004 1:07 pm

lol

by **MIK3Y** on Thu Mar 25, 2004 1:10 pm

AdrianFRST :
MIK3Y :Wrong, chatter is the wastegate snapping open and shut.

WRONG

Chatter is the air reverberating off the turbo blades when the throttle is closed.

U sure? I'm just saying what some1 in the know told me. :wink:

by **ianFRST** on Thu Mar 25, 2004 1:20 pm

without is better for performance. FROM personal experience.

by **AdrianFRST** on Thu Mar 25, 2004 1:55 pm

MIK3Y :
AdrianFRST :
MIK3Y :Wrong, chatter is the wastegate snapping open and shut.

WRONG

Chatter is the air reverberating off the turbo blades when the throttle is closed.

U sure? I'm just saying what some1 in the know told me.

Absolutely.

Think about what happens when you lift off:

The turbo isn't being asked to provide boost, so there is no need for the wastegate to open (which it only does when max boost is reached). Therefore it would not be opening and closing.

Even so, the wastegate is a metal flap against the metal casting of the turbo's exhaust housing. If it were to fluctuate, it would not produce the sound we know as chatter, more a metallic clattering sound.

The only sound you'll ever hear from the wastegate is external ones venting to atmosphere (screamer pipes).

by **MIK3Y** on Thu Mar 25, 2004 2:06 pm

I thought the waste gate was used to stop boost going back into the exhaust manifold/crankcase when a dump valve isn't being used because it gets pushed back thro the turbo and out the wastegate. I think it doesn't sound metalic because of pressurised air coming thro it so the air is making the noise.

Where does the boost go then when not running a dv?

by **AdrianFRST** on Thu Mar 25, 2004 2:53 pm

The wastegate is a flap inside the turbo which opens to leak boost out when it reaches a set amount. The wastegate actuator contains a spring and diaphragm that senses the pressure and opens the wastegate, as standard this happens at ~6psi (manifold pressure).

A dump valve (blow off valve outside Europe) is similar in construction to an actuator, in that it contains a spring and diaphragm (or piston). It's job is to open when the inlet manifold is in vacuum - throttle off on a turbo car.

When the throttle is lifted, boost produced by the turbo that has not yet entered the inlet has nowhere to go. Normally it bounces off the closed throttle plate and back towards the turbo, where it hits the spinning blades and reverberates off them, making the chattering noise. This can cause bearing failure and also in severe cases, the impeller blades to shatter and get sucked into the engine. Not a pretty sight.

Dump valves avoid this problem by releasing the excess boost to atmosphere. When the throttle is lifted the pressure in the inlet becomes a vaccum, this vacuum "sucks" the pipe that runs from the inlet to dump valve and causes the dump valves diaphram or piston to move, opening the valve. The boost that would normally be trapped is released.

Recircluating dump valves, or to use the proper name compressor bypass valves, do the same job but instead of venting to atmosphere, they recirculate the air back into the airbox or induction pipework. This avoids any noises as well as the airflow issues. Most production turbo cars use this type of valve.

by **AdrianFRST** on Thu Mar 25, 2004 2:56 pm

In most cases where people discover an increase in performance after removing the valve, it's down to the valve leaking boost or not functioning correctly in some other way.

by **Stoned** on Thu Mar 25, 2004 5:50 pm

I didnt notice any extra performance, but I did notice the pedal was a lot more responsive without the DV

GavRST found the same.

by **MIK3Y** on Thu Mar 25, 2004 5:56 pm

Me 2, must be still open a split second after going back on the gas with the dv on hence it not shortening lag as in theory it [ERRR] maybe?

by **andymac** on Thu Mar 25, 2004 7:30 pm

Let me get this straight then... removing the DV would cause there to to be a higher level of pressure than normal within the charge carrier immediately after throttle lift-off, right ? In fact, the air would have nowhere to go except back through the air intake system ?

When the throttle was opened the higher pressure air charge would immediately pass through the throttle body and into the plenum - effectively instant boost.

However when using a dump valve this excess boost is vented to the atmosphere / airbox, meaning that when you put your foot on the loud pedal, the system has to build up pressure again, causing a minute amount of lag.

This sound right so ??

by **kev RS** on Thu Mar 25, 2004 8:04 pm

AdrianFRST :
MIK3Y :Wrong, chatter is the wastegate snapping open and shut.

WRONG

Chatter is the air reverberating off the turbo blades when the throttle is closed.

y do you think they call it wastegate chatter

by **AndyRS1800** on Thu Mar 25, 2004 8:09 pm

Next week... K&N or Pipercross... Which is best... and how they make noise...

by **AdrianFRST** on Thu Mar 25, 2004 8:12 pm

The general concensus is that the slowdown of the turbo caused by the air hitting it is greater than the loss of inertia from a dump valve.

Having said that, a "general" average size turbo is bigger than a T2, and a small turbo at low boost pressure isn't as affected as say a T3/4 at 20psi.

My own car seemed to pick up better with the valve on. I do know though that the diaphragm was brand new when I was experimenting though.

ice mad :
AdrianFRST :
MIK3Y :Wrong, chatter is the wastegate snapping open and shut.

WRONG

Chatter is the air reverberating off the turbo blades when the throttle is closed.

y do you think they call it wastegate chatter

Because people (incorrectly) think that's what it is.

by **beanyfrst** on Thu Mar 25, 2004 8:20 pm

Ok so what i have gathered is that running the car without out the dump valve it feels more responsive but with the dump valve it stops the turbo from stalling.

So in theory it would be better running WITH the dump valve

by **turboboss** on Sat Mar 27, 2004 9:41 am

this is an extract from ahmed bajoo

Reckon sticking a dump valve on your engine will improve the performance and reliability of your car? Did you know that dump valves leak air and probably lose you tens of bhp? And that the back-pressure generated by a T2/T3 turbo would never be sufficient to 'shatter the turbo' as claimed by many tuning companies?

thanks

by **snake** on Sat Mar 27, 2004 5:55 pm

pimsle, quite funny this thread.... If dump valves were not required, and didn`t improve reliability (main reason for fitting them, why i run one) then wtf would ford fit recirc ones to cossies as standard :wink:

rs turbs etc don`t have them as standard they run 6-9psi, cossies run about a bar..

If u run more than 14psi, i would recommend running one. oh and not a s**t one, must be twin or filtered valve, don`t want crap goin in the engine under idle do yer :wink:

by **snake** on Sat Mar 27, 2004 6:00 pm

as for wastegate chatter, think about how the fook would a bit of metal last 5 mins under severe heat and stress that would be on it if it reverberated(sp) that much :lol:

andys spot on btw

oh as for cone filter, lol one word.. ABSOLUTE s**t!, every turbo i`ve looked at which has had one fitted has had damage to impellor blades on the turbo where grit has been gettin thu it, stick to panel filters :wink:

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