What did you do to your Polo today?

[louis19]

Attachment 22735pod in, needs cover as heat soak seems a lot worse (intake temps much higher than with the stock Airbox.

Cheap and easy mod.
2.75" to 3" silicone elbow, (eBay)
3x 3" hose clamps, (bunnings)
Saas pod (super cheap)
3" coupler (76mm pvc pipe is fine) bunnings
Stanley knife and screw driver.

Haven't bought a filter for the Sai intake yet, just have a rag cable tied over the hole.


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Good Job mate! Unrelated, but is your DV installed incorrectly? Hard to see it fully in the picture, but the orientation appears the wrong way around?

[Blue9N3]

DV is Correct according to forge, but opposite to the factory setup.

Factory setup is probably better as boost actually keeps the valve shut rather than trying to lift it, but forge recommend not to put the splitter valves in backwards. Dunno why.


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[sambb]

Basically all piston style DV's are oriented that way. You have the inlet boost pressure acting on only a small area at the base of the piston - its not really feasible that this boost pressure is going to push it open against both the spring and the manifold pressure signal. Diaphragm valves can go either way but its more conventional to have them in the stock orientation.

[h100vw]

Basically all piston style DV's are oriented that way. You have the inlet boost pressure acting on only a small area at the base of the piston - its not really feasible that this boost pressure is going to push it open against both the spring and the manifold pressure signal. Diaphragm valves can go either way but its more conventional to have them in the stock orientation.

I had an AUM engined A3 that only made 15PSI on a stage 1 tune with the DV fitted backwards. I wouldn't fit one except with the boost on the side of the piston. Regardless of the theory that the spring and boost up the cap should keep it closed.

[sambb]

Gav was that a piston style DV that you are saying you would only fit with the charge pipe pressure coming into the side of the piston?

[h100vw]

Gav was that a piston style DV that you are saying you would only fit with the charge pipe pressure coming into the side of the piston?

Correct, this particular A3 was losing 5-6PSI.

Gavin

[sambb]

Ok. Sounds like it either had a weak spring that was causing piston creep or the seal at the base of the piston was turd ie it couldn't prevent boosted air getting past it but in the other configuration could seal against the atmospheric pressure inside the TIP.
hmm I know that some piston dv's have a ring bore seal. If air comes in from the side the only way it can escape is through to the TIP when the piston is pulled open. My turbosmart though doesn't have a ring bore seal - it is a machined flush sliding fit but doesn't make a perfect seal. eg If you do the test where you hold the piston up with your finger and then suck on the manifold signal, it will fail - the piston won't float statically. It will however open in response to a big spike in manifold vacuum. ie if my DV is configured the same way as the OEM diaphragm one, then manifold vacuum when off boost would be able to suck air around the sides of the piston from the inlet charge pipe or when a boost spike occurs, pressurised air can get to the manifold signal side and actually work on the back of the piston to keep it shut when it should be opening.
It might depend on if the piston style DV is bore sealed or not as to which way it can be run.

[h100vw]

Ok. Sounds like it either had a weak spring that was causing piston creep or the seal at the base of the piston was turd ie it couldn't prevent boosted air getting past it but in the other configuration could seal against the atmospheric pressure inside the TIP.
hmm I know that some piston dv's have a ring bore seal. If air comes in from the side the only way it can escape is through to the TIP when the piston is pulled open. My turbosmart though doesn't have a ring bore seal - it is a machined flush sliding fit but doesn't make a perfect seal. eg If you do the test where you hold the piston up with your finger and then suck on the manifold signal, it will fail - the piston won't float statically. It will however open in response to a big spike in manifold vacuum. ie if my DV is configured the same way as the OEM diaphragm one, then manifold vacuum when off boost would be able to suck air around the sides of the piston from the inlet charge pipe or when a boost spike occurs, pressurised air can get to the manifold signal side and actually work on the back of the piston to keep it shut when it should be opening.
It might depend on if the piston style DV is bore sealed or not as to which way it can be run.

Pretty sure this was a turbosmart and changing the orientation did fix it. I didnt expend any time working out why

[sambb]

I know a lot of people run the OEM diaphragm style DV's switched around, but I'd honestly never thought of doing it with a piston style. I might switch mine and see if it feels any different.

[HAR80N]

Got me some new Audi R8 Coil Packs And Spacers