Boost without wastegate hose?

[shone190]

Hi everybody.

I was wondering, what boost do I need to have with this wastegate hose off?



Also, I saw that somebody is "playing" with bolt on top of the wastegate. Is there a way to back the bolt on "stock" position?

At the moment, I have problem with boost, maximum is 0.4bar. Without wastegate hose, maximum boost is about 0.7-0.8bar.
What does it mean?

Thank You very much in advance!

[Rusty]

You don't want to disconnect that hose, as it stops the car over-boosting.

With the hose connected and the N75 electrically unplugged, the boost should be 0.4 bar at about 3000 rpm on a stock engine.

If the car is not boosting more than 0.8 bar with the hose disconnected then you have a leak in the inlet or exhaust (pre turbo).

[UrS4boy]

Wastegate Frequency Valve info

Without that hose, you are only getting mechanical boost provided by the wastegate spring under that cap. If you turn the adjustment screw up, you get less boost, if you screw it down, you will get more boost - but only to the limit of the spring, e.g. 0.6 to 0.8 Bar. To get more boost, you need to have the wastegate frequency valve electrically connected to the ECU and mechanically connected to the turbo and the wastegate. Here is some information that might help you:

http://forums.quattroworld.com/s4s6/msgs/20987.phtml

[UrS4boy]

I just updated my link to include this diagram (for an AAN but the principles also apply to the 3B, ABY and ADU)

[andyg plym]

hey man,

where can i get that program (etka?) from?

thanks

[Rusty]

The boost opens the WG, not closes it... the pressure exerted on the diaphragm pushes upwards against the spring, it doesn't assist it; in fact it opposes it. Not having that hose on means that the only thing opening the WG is the pressure exerted on the WG piston by the exhaust gases in the manifold and so the WG will stay shut and the turbo will boost to it's full capability!

The 'mechanical boost' people refer to is actually what happens when the full boost in the inlet is fed into the WG and not metered by the N75. When the force exerted on the diaphragm by the pressure in the lower chamber matches that of the spring pre-load, the WG opens and the boost is regulated. This is why a stonger spring gives more base boost and why winding the spring adjuster down gives more boost - they have more preload.

If you don't believe me, then put the lower chamber to atmosphere and see what happens

[driftin jo]

Without that hose, you are only getting mechanical boost provided by the wastegate spring under that cap. If you turn the adjustment screw up, you get less boost, if you screw it down, you will get more boost - but only to the limit of the spring, e.g. 0.6 to 0.8 Bar. To get more boost, you need to have the wastegate frequency valve electrically connected to the ECU and mechanically connected to the turbo and the wastegate. Here is some information that might help you:

http://forums.quattroworld.com/s4s6/msgs/20987.phtml

that's not right, without that hose connected the waste gate will not open, well it may open a little due to exhast pressure, but you dont get spring only boost as the gate is opened by boost pressure ! Try it if you don't belive me you will get overboost cut, turbo will spool very quick as there is no boost pressure opening the gate.

[shone190]

Thanks everybody, but what's conclusion at the end? Who is right?

Do I have defintely have a boost leak based on 0.7-0.8bar with wastegate hoseoff?

Can I adjust bolt on wastegate or there is no point to "play" with it?

How much boost could I expect without boost leak and with everything in perfect condition, with wastegate hose off?

Thanks again

[driftin jo]

with regards to the first post i think you are only getting low boost with that hose off as a result of the waste gate being jammed open because if it was in good working order you would get over boost in a second. the only other explanation is your turbo is ****ed.

[driftin jo]

Thanks everybody, but what's conclusion at the end? Who is right?

Do I have defintely have a boost leak based on 0.7-0.8bar with wastegate hoseoff?

Can I adjust bolt on wastegate or there is no point to "play" with it?

How much boost could I expect without boost leak and with everything in perfect condition, with wastegate hose off?

Thanks again

how much boost with a leak ?!?!??? how long is a piece of string

[shone190]

How much boost WITHOUT leak

[driftin jo]

How much boost WITHOUT leak

with the waste gate hose off you will have a leak(unless you plug it) , but you will also have maximum boost and potentially engine ready to put a rod throught he crank case if you safe gaurds are not working to cut the fuel.

[shone190]

I plugged hose with bolt when I took it off, so I "didn't have boost leak"

[UrS4boy]

that's not right, without that hose connected the waste gate will not open, well it may open a little due to exhast pressure, but you dont get spring only boost as the gate is opened by boost pressure !

Sorry, I wasn't actually thinking that he had the hose removed per se, just that it was connected to a dead or unplugged WGFV. I would never advocate actually removing that hose from the WG. My bad.

[UrS4boy]

hey man, where can i get that program (etka?) from?
thanks

VagCat and a box of crayons?