chrisdenton
New member
Excuse my ignorance but what are the purpose of wastegate shims? I understand they sit either side of the wastegate but what do they do and why do some suppliers level 1a have them and others dont?
Wastegate shims
- Thread starter chrisdenton
- Start date
sawood12
New member
DPW's are great. My car is essentially standard apart from the DPW (boost level set to 0.8 bar which is stock) and it got 237.5bhp on the Weltmiester rolling road day. So your leaky wastegate is worth at least 17.5bhp - probably more than that as my 17yr old leaky wastegate with a big crack in the housing was undoubtedly not even achieving 0.8 peak boost so bhp would have been well down on the 220bhp it should have been. You should get even more on a 250bhp car as the turbo can hold boost upto the red line whereas mine can only deliver 0.6 bar at the red line and your stock wastegate wont be able to hold the max boost all the way to the red line.
Turbo lag is still there but boost comes in earlier in the rev range and very quickly and strongly so you need to be very carefull in slippery conditions.
Get one!!
Turbo lag is still there but boost comes in earlier in the rev range and very quickly and strongly so you need to be very carefull in slippery conditions.
Get one!!
Diver944
Active member
Chris, if you are still on the original wastegate you should definitely shim it.
For the cost of a few washers and a few hours under the car (and a few bruised knuckles) you will get your full performance back as the factory intended. You only need to go for a new wastegate when you want to start increasing the performance with more boost, or reducing the lag with boost lower down the rev range [8D]
For the cost of a few washers and a few hours under the car (and a few bruised knuckles) you will get your full performance back as the factory intended. You only need to go for a new wastegate when you want to start increasing the performance with more boost, or reducing the lag with boost lower down the rev range [8D]
sawood12
New member
Doesn't a boost enhancer give the same effect as shims? My understanding is that the boost enhancer doesn't expose the wastegate pressure input to any high levels of boost pressure until boost hits the preset pressure level? Wastegate shims simply preload the spring so when the boost signal into the wastegate reaches the right level the pressure opens the wastegate but again you are relying on spring pressure to resist the boost pressure signal upto the point it hits max boost(?)
I would imagine a boost enhancer is a damn sight easier to fit than wastegate shims.
I would imagine a boost enhancer is a damn sight easier to fit than wastegate shims.
Diver944
Active member
Your right Scott but the shims and the boost enhancer do different jobs.
The boost enhancer delays boost pressure from entering the top chamber of the wastegate and opening the valve until you want it to.
The shims put more preload on the spring inside the wastegate and keeps the valve from opening prematurely by mere exhaust pressure alone. If you have a really tired and weak spring, then the valve will start to open as soon as exhaust gases come out of the engine, no matter what you set the boost enhancer to and will send lovely exhaust gases straight out the tailpipe and not into the Turbocharger [
]
The boost enhancer delays boost pressure from entering the top chamber of the wastegate and opening the valve until you want it to.
The shims put more preload on the spring inside the wastegate and keeps the valve from opening prematurely by mere exhaust pressure alone. If you have a really tired and weak spring, then the valve will start to open as soon as exhaust gases come out of the engine, no matter what you set the boost enhancer to and will send lovely exhaust gases straight out the tailpipe and not into the Turbocharger [
]That;s about right, except that in the standard configuration you also have the cycling valve which is interrupting the wastegate signal under the control of the KLR computer.![[FONT=verdana,geneva"]](/forum/styles/default/pcgb/space.gif ". [FONT=verdana,geneva\"]")
Where you are slightly disadvantaged by just a boost enhancer is that the wastegate spring acts to close the valve against the pressure rather than the pressure acting to close the valve until a diaphragm controlled by the pressure feed from the banjo bolt opens the valve (hence my saying above it is a poor design). This means that the wastegate relies entirely on the spring and they are normally so weak by now that virtually no pressure at all unseats the valve. Remember the BE is only interrupting the control line pressure and the actual pressure that does the work still hits the wastegate valve regardless of a BE or not. That pressure opens the valve against the weak spring and bleeds away, but with washers to preload the spring the wastegate has a better chance of staying closed until it is supposed to be open. Sorry if that isn't clear, we've been making (read sampling) eggnog []
Where you are slightly disadvantaged by just a boost enhancer is that the wastegate spring acts to close the valve against the pressure rather than the pressure acting to close the valve until a diaphragm controlled by the pressure feed from the banjo bolt opens the valve (hence my saying above it is a poor design). This means that the wastegate relies entirely on the spring and they are normally so weak by now that virtually no pressure at all unseats the valve. Remember the BE is only interrupting the control line pressure and the actual pressure that does the work still hits the wastegate valve regardless of a BE or not. That pressure opens the valve against the weak spring and bleeds away, but with washers to preload the spring the wastegate has a better chance of staying closed until it is supposed to be open. Sorry if that isn't clear, we've been making (read sampling) eggnog []
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