Dump / BOV / Wastegates
- Thread starter ramirez
- Start date
Caporegime
- Joined
- 11 Mar 2005
- Posts
- 32,222
- Location
- Leafy Cheshire
If you get a good one can't they extend the life of the turbo?
Soldato
- Joined
- 18 Oct 2002
- Posts
- 3,497
- Location
- Harlow, Essex
every turbocharged engine has a waste gate to stop overboosting and a big mess under the bonnet IIRC dump valves aren't so cirtical they dump bulit up pressure in the turbo when you come of the throttle to stop fanblades from stalling and helps with a quicker spool up IIRC 
Oh here we go again.
Firstly lets clear up the 'wastegate' issue. As needmorespeed says, you will already have a wastegate. The wastegate only opens when you're on the throttle to stop the turbo overboosting. As it opens it bleeds away excess boost, stopping your engine blowing up. All this talk of 'OMG did you hear the wastegate on that when he came off the throttle' is BS. The flutter/chooo chooo cho noise they're reffering too is Compressor Surge - and is actually the noise of air escaping through the turbo backwards back to atmosphere.
As for dump valves being needed, cos your turbo will die - this is utter tripe. Unless you're running serious, serious boost this isn't the case. Dump valves kill your throttle response, since the turbo has to spool up again from scratch. When the system has boost in it because it's harder to leak away, your throttle response is a lot sharper. Dump valves are there for show and to turn heads. Recirc valves are used to quieten the car down.
Firstly lets clear up the 'wastegate' issue. As needmorespeed says, you will already have a wastegate. The wastegate only opens when you're on the throttle to stop the turbo overboosting. As it opens it bleeds away excess boost, stopping your engine blowing up.
All this talk of 'OMG did you hear the wastegate on that when he came off the throttle' is BS. The flutter/chooo chooo cho noise they're reffering too is Compressor Surge - and is actually the noise of air escaping through the turbo backwards back to atmosphere.As for dump valves being needed, cos your turbo will die - this is utter tripe. Unless you're running serious, serious boost this isn't the case. Dump valves kill your throttle response, since the turbo has to spool up again from scratch. When the system has boost in it because it's harder to leak away, your throttle response is a lot sharper. Dump valves are there for show and to turn heads. Recirc valves are used to quieten the car down.
Soldato
- Joined
- 24 Oct 2002
- Posts
- 6,242
- Location
- Portsmouth
Can you actually have a dump valve on a automatic?
I cant think of an automatic that had one
I cant think of an automatic that had one
I thought a dump to atmos or recirculating valve was to expel excess pressue when you come off power. This stops the turbo stalling. If you didn't have one of these, your turbo would stall every time you change gear meaning that on every gear change, you turbo would have to spool up again.Lowe said:As for dump valves being needed, cos your turbo will die - this is utter tripe. Unless you're running serious, serious boost this isn't the case. Dump valves kill your throttle response, since the turbo has to spool up again from scratch. When the system has boost in it because it's harder to leak away, your throttle response is a lot sharper. Dump valves are there for show and to turn heads. Recirc valves are used to quieten the car down.
The only difference between a dump to atmos and a recirc is where it puts the excess air.
Admittadely, I only have first hand experience with my current turbo'd car, but I'm pretty sure all manufacturs put a recircuating dump valve on them as standard. I dont think they would do that if it wasn't nessecary, or at least beneficial to the car.
As above, I think all turbo's cars will have a 'dump valve', only they will be a recirculater, so you wont hear any 'tsst'. Plus an auto would be less aggressive on the gear changes, so you're less likely to make it do so much.Stonedofmoo said:
Soldato
- Joined
- 24 Oct 2002
- Posts
- 6,242
- Location
- Portsmouth
Nah Ford never fitted a dump valve of any type on the RS Turbo's and i'm sure other cars with smaller turbochargers such as the Smart cars dont have one either. There's simply no point when such little boost is involved.
Soldato
- Joined
- 22 Aug 2004
- Posts
- 7,607
Stonedofmoo said:
all depends on the car! mine has a factory fitted recirc that i changed to a hks bov
Soldato
- Joined
- 22 Aug 2004
- Posts
- 7,607
hey dont diss it kicks some, 12psi as stock, and the hks power assist kit takes it upto 16 psi 
Soldato
- Joined
- 24 Oct 2002
- Posts
- 6,242
- Location
- Portsmouth
Well there you go, 12psi is quite a fair bit
The RS Turbo's ran 7psi!
The RS Turbo's ran 7psi!
Soldato
- Joined
- 22 Aug 2004
- Posts
- 7,607
daihatsu are a bit mad they been turboing small engines for donkeys years one of the originals was 500cc 2 cylinder turbo 
Bug One said:
No not all cars had recircs as standard. The s13 200sx didnt for instance. TBH its mainly dependant on boost and perhaps quieten down the car. If the turbo doesnt have a full 360 degree bearing as some have 270 deg journals, then if you're running high boost then the compressor stall can put quite a bit of side ways loading on the shaft which can cause premature bearing wear. On a turbo with 360degree bearings it isnt that much of a problem unless you're running crazy boost.
When I fitted a FMIC, my recirc packed in for some unkown reason and have been running 15psi and then 17psi without any problems without the recirc working.