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I guess this is my next project - I am running stock boost but after 4 years with 2 good years of hard abuse, I am likely due.
QQ - if as 4Point0 says, with these after market valves, more boot pressure forces the valves closed (more). Is there an issue or risk of too much pressure causing some other failure because these don't blow off when needed?
No, because they only open when you get off it. They are not fighting to open as you have lifted.
And they are not fighting to stay closed, as the boost holds them closed. They aren’t being closed more, they are merely staying closed, like they are meant too, under pressure.
The OEM are really a very old design flaw.
Again, anyone driving miss Daisey would never notice even if the OEM failed.
I did this mod about 2 years ago in hope of increasing the blow off noise slightly. There was no increase in noise but at certain load and RPM there is a slight difference in blow off tone when lifting off he throttle sharply. I did this install without removing the rear bumper or heat shields. I was able to sneak them in just by removing the rear portion of the fender liner.
EDIT: DO NOT ORDER FROM THIS COMPANY. THEY COMPLETELY SCREWED ME ON MY ORDER. UPDATED POST BELOW.
Rolling the dice on this one. Price seems almost too good. I emailed APR and they said this is indeed an authorized dealer. $212.31 for a pair shipped which includes a 10% discount offered on the site. Free shipping.
After making my purchase, they sent me a 'refer a friend' link that you can use for an additional $10 off your purchase (for full transparency they in turn send me a $10 voucher too). So you can essentially get the APR DV for $202.21 shipped.
Rolling the dice on this one. Price seems almost too good. I emailed APR and they said this is indeed an authorized dealer. $212.31 for a pair shipped which includes a 10% discount offered on the site. Free shipping.
After making my purchase, they sent me a 'refer a friend' link that you can use for an additional $10 off your purchase (for full transparency they in turn send me a $10 voucher too). So you can essentially get the APR DV for $202.21 shipped.
What the hell!!! I wasn't planning to buy any valves for a few month's but the price is so good, even shipped to the UK (It's FREE!)... Seems too good to be true so I have paid with CC for protection...
This is a good price! I also ordered from MBenzGram and I thought I was getting a good deal. I got mine in December 2020 though. The only drawback was the time it took to receive, they took forever.
Are the APR valves installed in the same orientation as stock valves?
Others answered your question so you know the answer is Yes. But there was a thread in the 991 turbo forum too about APR's diverter valve orientation - and I think it centered around the idea that it was odd for the APR valves to be oriented the same way as OEM, meaning the pressure side would be acting on the spring in the valve to possibly push it open under boost and thus leak. If you care to read it, here is a link to that thread: https://rennlist.com/forums/991-turb...ntation-2.html
As others posted here, the opposite is preferable where the pressure side if forcing the valve closed until there is a vacuum state (i.e. throttle plate closed) and the valve is mechanically pulled open. So, why would APR want their aftermarket valves to be installed the same way as OEM?
Others answered your question so you know the answer is Yes. But there was a thread in the 991 turbo forum too about APR's diverter valve orientation - and I think it centered around the idea that it was odd for the APR valves to be oriented the same way as OEM, meaning the pressure side would be acting on the spring in the valve to possibly push it open under boost and thus leak. If you care to read it, here is a link to that thread: https://rennlist.com/forums/991-turb...ntation-2.html
As others posted here, the opposite is preferable where the pressure side if forcing the valve closed until there is a vacuum state (i.e. throttle plate closed) and the valve is mechanically pulled open. So, why would APR want their aftermarket valves to be installed the same way as OEM?
Hmm I suppose the same thing could be said about the stock valves, f6 valves and any others who suggest their valves should be installed in same orientation. I imagine with piston type valves there is a bigger benefit.
I did read lot's about reverse orientation on the 1.8t forums (which use the same valve) but it never really took traction and most run or swapped back to stock orientation.
Others answered your question so you know the answer is Yes. But there was a thread in the 991 turbo forum too about APR's diverter valve orientation - and I think it centered around the idea that it was odd for the APR valves to be oriented the same way as OEM, meaning the pressure side would be acting on the spring in the valve to possibly push it open under boost and thus leak. If you care to read it, here is a link to that thread: https://rennlist.com/forums/991-turb...ntation-2.html
As others posted here, the opposite is preferable where the pressure side if forcing the valve closed until there is a vacuum state (i.e. throttle plate closed) and the valve is mechanically pulled open. So, why would APR want their aftermarket valves to be installed the same way as OEM?
The proper orientation is the same as stock. This picture is from polobai of the stock valve attached to the intake tube and I drew in the flow path when it blows off; high pressure air dumping into the low pressure intake tube.
How does the APR and other aftermarket valves work? The internal diaphragm of the APR design that is roughly double (eyeballing it) the diameter of the valve that seals against the high boost pressure side. Double the diameter means four times the area. Pressure (pounds per sq. inch) x Area (sq inches) = Force (pounds). For simplicity sake, the pressure on the high boost side of the small diameter valve is equal to the pressure on top of the diaphragm connected to the high boost of the intake manifold. Therefore, the Force acting on top of the diaphragm that is pushing the valve down to seal on the high boost tube is 4x greater. So you can see, the valve will never open under boost because much greater force is pushing down due to the greater area of the diaphragm.
Notice the ratio of diaphragm diameter to sealing valve diameter of the APR design looks much greater than the OEM part. I haven't taken apart an OEM Bosch unit, but they typically have a little bleed valve inside that causes the valve to open at high boost levels to act as a mechanical failsafe incase the car overboosts for some reason.
Last edited by spdracerut; 01-19-2022 at 10:31 PM.
The proper orientation is the same as stock. This picture is from polobai of the stock valve attached to the intake tube and I drew in the flow path when it blows off; high pressure air dumping into the low pressure intake tube.
How does the APR and other aftermarket valves work? The internal diaphragm of the APR design that is roughly double (eyeballing it) the diameter of the valve that seals against the high boost pressure side. Double the diameter means four times the area. Pressure (pounds per sq. inch) x Area (sq inches) = Force (pounds). For simplicity sake, the pressure on the high boost side of the small diameter valve is equal to the pressure on top of the diaphragm connected to the high boost of the intake manifold. Therefore, the Force acting on top of the diaphragm that is pushing the valve down to seal on the high boost tube is 4x greater. So you can see, the valve will never open under boost because much greater force is pushing down due to the greater area of the diaphragm.
Notice the ratio of diaphragm diameter to sealing valve diameter of the APR design looks much greater than the OEM part. I haven't taken apart an OEM Bosch unit, but they typically have a little bleed valve inside that causes the valve to open at high boost levels to act as a mechanical failsafe incase the car overboosts for some reason.
It looks to me like the OP and Dark Horse have their hi pressure (smaller) hose installed perpendicular to the vacuum line, OPPOSITE of the stock diverter. I had World's install mine like this last summer on APR's advice. Car is running fine and is 3/10's quicker 60-130. I did have the inlets and pipes installed at the same time.
?????
I went with Turbosmart Kompact 25mm valves with my TiAL setup. Not sure why people are installing them in reverse orientation, it’s very clear where the air pressure needs to push up against the diagram/spring and exit out the 90 degree outlet just like OEM.
And just for fun, this is the factory 2017 991.2 diverter valve compared to a 2001 Audi S4. Same manufacturer and same general design as a diverter valve used by Audi over 20 years ago. Bet you guys don’t know which is the Porsche DV and which is the 20 year old S4 DV 😉
Last edited by AlexZTuned; 01-20-2022 at 11:49 AM.
01-18-2022, 08:35 PM
