Turbo wastegate

[dieselboy]

i think you might be wrong there,standard dump valves as fitted to say cosworth,rs, dump the hot air back into the air flow this is because of emission laws,
this is EGR and not a boost dump valve. non turbo cars have these, diesel and petrol
non standard ones dump the excess air pressure into the atmosphere
this is to make the noise
,this is to allow the air entering the engine to be a cold as possible
this doesnt let this happen. when the boosted air is dumped, it doesnt let any more air to be let in.
the dump valve works by sensing a vacuum between the inlet manifold butterfly and the pistons.. ie, the butterfly is closed because you have taken your foot off the accelerator to stop letting air in, but the pistons still move up and down and they truck to suck in. this vacuum moves a piston which then opens like a valve to release the boosted air to give off that sweet noise . all the audiable dump valve would do, is ease pressure on the butterfly because it releases the force acting on it.
when the next gear is selected, the turbo would have slowed some, and also the engine speed will have dropped into the next gear. to get the turbo back up to speed more air and fuel will need to be burnt to get gasses through the exhaust impeller to create boost.
a different kind of setup will not be audiable. but instead of releasing the boosted air into the engine bay, **it will be released into the exhaust manifold before the exhaust impeller, this will keep the turbo spooled up so as provide immediate power after the gear change**,same thing with engine breathers.
no, engine breathers allow the pressure in the rocker cover to be vented

the bits between the ** are vauge to me, im not sure if the boosted air gets re-circulated around the inlet impeller or makes a change from the induction to the exhaust like what i described.


do diesels even have this butterfly? from what i understand, they dont work on vacuums like petrol cars. this is why we have a pump driven off a belt to pump up our servos for our brakes etc. and its probably why my boost gauge reads 0psi most of the time at tick over. it does read negative certain times tho.

[NiftyNev]

When you lift off when changing gear, the turbo slows down as there is nowhere for the air on the pressurized side to go, a dump valve allows this pressurized air to be released and therefor allowing the turbo to keep spinning, which means when you step on the gas again you don't have a delay (lag) before the turbo is up to speed again.

So technically a dump valve won't give you more power, but will give better performance.

Not a great advantage on a low revving diesel, but very noticeable on a performance petrol engine.

Correct. A Dump Valve (BOV) will work on the manuals. Pretty well useless on an auto.

Nev

[NiftyNev]

do diesels even have this butterfly?

Yes the Surf 2.4 has a butterfly and maybe even the 3Ltr. There is a very slight vacuum at idle but not enough to operate the brakes etc so they have a vacuum pump on the alternator for the 2.4s and gear driven on the 3Ltr. If the throttle is closed suddenly then there is more vacuum for a short period. A Dump Valve (BOV) will help to stop the pressure wave against the intake turbine during gear changes. It has to be set up just right though.

Nev

[Apache]

One could always inject fuel into the turbo during gear changes to keep the turbo spinning as per GpB.... Mmmmm... GpB....





Something to drool over on a wet Sunday morning.

Now THAT's what I'm talking about! Holy cow, these things would EAT WRC for breakfast and come back for more! I remember seeing these things in the hands of Hannu Mikkola and Michele Mouton in the forests of North Wales. The noise, the speed, the visceral ###### alien-ness of them made your spine tingle!

[dieselboy]

OMG thats just too much excitement!!!!!

One could always inject fuel into the turbo during gear changes to keep the turbo spinning as per GpB.... Mmmmm... GpB....

mmmmmnnnn an anti-lag turbo!! dont expect a 100,000 mile lifetime of your turbo though lol

[Dodge]

im sorry but audiable dump valves do not give any performance gain what soever. whether it be torque or hp it gives nothing but a noise.

No need to be sorry, being wrong is nothing to be ashamed of.

A dump valve's purpose isn't to make a noise . . . unless you have a Saxo!
They are, as I stated in my previous post, there to vent off pressurized air, thus allowing the turbo to keep spinning rather than be slowed by the back pressure from the build up of air that has nowhere to go. When you then apply the gas there is no delay (lag) in the turbo coming in, thus a performance gain, no extra power or torque, but a real performance gain.

Also, if a turbo is slowed on the induction side it also slows on the exhaust side, removing exhaust gasses is as important to engine performance as getting it in in the first place.

[lord lucan]

the bits between the ** are vauge to me, im not sure if the boosted air gets re-circulated around the inlet impeller or makes a change from the induction to the exhaust like what i described.


do diesels even have this butterfly? from what i understand, they dont work on vacuums like petrol cars. this is why we have a pump driven off a belt to pump up our servos for our brakes etc. and its probably why my boost gauge reads 0psi most of the time at tick over. it does read negative certain times tho.

Most production turbocharged engines are fitted with a dump valve. This is to vent away excessive turbocharger boost pressure when the throttle is closed.
All Sierra Cosworth and the original large turbo Escort Cosworth models use the same dump valve. The turbocharger fitted to the latest Escort Cosworth has its own integral unit.
The dump valve is the black plastic saucepan shaped object that you will see connected between the intercooler and the air inlet hose to the turbocharger. You will also see a small hose leading from the top of the valve to the inlet plenim on the engine. Inside the valve is a rubber diaphragm and a steel spring, with a small insert to support the diaphragm where it seats against the dump valve body.
The dump valve has basically two operating conditions; throttle open, and throttle closed. When the throttle is open, the boost pressure coming into the valve from below the diaphragm is equalled by the pressure onto the top of the diaphragm that comes via the small hose from the engine plenim chamber. As the pressures are equal, the spring holds the diaphragm onto its seat, and prevents the pressure venting away. When the throttle is closed, the pressure coming into the top of the valve is significantly reduced, (often to a vacuum), and the pressure below the diaphram lifts it away from its seat, allowing the excess pressure to vent away. As the throttle is reopened, the pressures again equalise, the spring pushes the diaphragm onto its seat, and the boost pressure cannot vent away.



Why do manufacturers fit a dump valve?

It is for a number of reasons. Without a dump valve, when the throttle was closed, the build up of boost pressure would be immense, very similar to closing a quickly flowing water tap. This excess of pressure, (which could be over five times the running boost pressure), would put the components of the system under a great strain. It would try to burst the intercooler and pipework. More significantly, it would put a large strain on the turbocharger itself, firstly stalling the compressor shaft, then trying to force the compressor wheel out of the turbo, against its bearings.
So, the dump valve prevents mechanical damage to the intercooler & turbo pipework, prolongs turbocharger life, and prevents excessive turbo - lag that would be caused by the compressor shaft stalling.

[dieselboy]

No need to be sorry, being wrong is nothing to be ashamed of.

A dump valve's purpose isn't to make a noise . . . unless you have a Saxo!
They are, as I stated in my previous post, there to vent off pressurized air, thus allowing the turbo to keep spinning rather than be slowed by the back pressure from the build up of air that has nowhere to go. When you then apply the gas there is no delay (lag) in the turbo coming in, thus a performance gain, no extra power or torque, but a real performance gain.

Also, if a turbo is slowed on the induction side it also slows on the exhaust side, removing exhaust gasses is as important to engine performance as getting it in in the first place.

lol
saxos dont have turbos
im not going to get into another one of these post thingys i seem to always get myself in. so...
hi, im tony

[darkdezigns]

let me put it simply,is it possible to fit a dump valve and get a tiiiiiiiiiiiiishhh,thats all i wanna know lol

[dieselboy]

let me put it simply,is it possible to fit a dump valve and get a tiiiiiiiiiiiiishhh,thats all i wanna know lol

well according to what nev said, there is a vacuum albeit only small on our engines. so as long as this is enough to pull the piston then yes.
but usually on diesels the answer is no.
but get a cone filter and put it on your turbo and drive down the road, cos thats all that has been done to mine, and ive got a dump valve noise coming from somewhere. ask dave.

[That Ruddy Squirrel]

Are you sure you want a 'tiiiiiiiiiiiiishhh' or a quack

[darkdezigns]

well according to what nev said, there is a vacuum albeit only small on our engines. so as long as this is enough to pull the piston then yes.
but usually on diesels the answer is no.
but get a cone filter and put it on your turbo and drive down the road, cos thats all that has been done to mine, and ive got a dump valve noise coming from somewhere. ask dave.

i reckon it wud work,im running a 4.2 lc turbo on over boost!

[dieselboy]

Are you sure you want a 'tiiiiiiiiiiiiishhh' or a quack

haha!! what about a chicken noise?

[That Ruddy Squirrel]

haha!! what about a chicken noise?

It's BD2 not joker

[darkdezigns]

It's BD2 not joker

yep bdt2 who tried fitting light bar again today,and it packed up again,almost threw it down the road lol