Recirculating dumpvalve installation

[Squirtydog]

OK. Having decided to go for Ron's new Mountain chip upgrade while it is available, I plan to install a RDV before running the higher boost. I can hear turbo chatter with the car standard, so I assume that this is a worthwhile mod regardless. I have trawled the search function - there are a lot of references out there - so I hope that I am not adding to the search results unnecesarily. Hopefully this will help me and anyone else who needs a Dump Valve for Dummies installation guide.

So, having seen lotusflasherman Phil's description of his installation I think I will try to replicate the same.

Here's what I think i have gleaned... Please be gentle

1. Dump valves are relatively universal - I have seen people reference preferred valves (Bailey DV30 for example) but also cheap ebay items.
Q: Is there something I am missing in terms of suitable and unsuitable valves for our cars? Some are supplied with a choice of spring.
2. There is variation in the size of the ports and hence the hose required, but 25mm is common.
Q: Does it really matter?
3. I have seen reference to the induction hose on the Elan being internal diameter 57mm but also 60mm
Q: Is it close to both? Do I just cut and measure and choose a T piece to fit?

Here is a shopping list, with some current sources.

1. Recirc dump valve
New forge item HERE £120
Ebay VAG forge item HERE £50
2. T-piece 57mm HERE £11
3. 25mm silicone hose HERE £14
4. 25mm blanking plug - to be drilled out - attaches with shoulder inside the dustbin HERE £4.50
5. Length of vacum hose - universal.

Thanks in advance. Please educate me.

[Fredjohn]

Sorry can't answer some of your questions, but I have a Forge dump valve fitted. Came with the car. Don't know which one though. I did get a small repair/seal kit for it though as it was leaking slightly.
Mine uses a T piece fitted into the inlet hose.
Mine vents to the open air, but I put some suitable foam over it to kill the chavvy whistle. Better still is to get one to vent back into the air filter box. No chav sounds that way either.

[Squirtydog]

...Better still is to get one to vent back into the air filter box. No chav sounds that way either.

Thanks. Yep. The plan is to vent back into the air box. Looks like a very manageable installation.

[Squirtydog]

OK. Having decided to go for Ron's new Mountain chip upgrade while it is available, I plan to install a RDV before running the higher boost. I can hear turbo chatter with the car standard, so I assume that this is a worthwhile mod regardless. I have trawled the search function - there are a lot of references out there - so I hope that I am not adding to the search results unnecesarily. Hopefully this will help me and anyone else who needs a Dump Valve for Dummies installation guide.

So, having seen lotusflasherman Phil's description of his installation I think I will try to replicate the same.

Here's what I think i have gleaned... Please be gentle

1. Dump valves are relatively universal - I have seen people reference preferred valves (Bailey DV30 for example) but also cheap ebay items.
Q: Is there something I am missing in terms of suitable and unsuitable valves for our cars? Some are supplied with a choice of spring.
2. There is variation in the size of the ports and hence the hose required, but 25mm is common.
Q: Does it really matter?
3. I have seen reference to the induction hose on the Elan being internal diameter 57mm but also 60mm
Q: Is it close to both? Do I just cut and measure and choose a T piece to fit?

And Q4: Can anyone share a picture of, or explain where the vacuum hose attaches at the other end?

[Squirtydog]

So I have completed the installation. This is a very easy job and I suspect that this 'how to' is surplus to requirements for most. It at least brings together everything I read on the many thread references on here and is basically the method described by lotusflasherman Phil in various posts along with some advice from RonR. Thank you to you both. I hope that this is of some help to others like me, who have never tackled hacking into hoses etc. and even had to look up 'step drill bit'.

My final full shopping list was:
1. Second hand Forge dump valve (FMCL007P)- came with the (I believe) appropariate green spring £50
2. Forge service kit £17.50 HERE
3. 25mm straight silicone hose £14 HERE
4. 25mm flexible silicone hose. £12. HERE
5. 25mm blanking plug £4.50 HERE
6. 57mm to 25mm T-piece £11 HERE
7. 3.5mm internal diameter vacuum hose £5.50 - HERE This is a little small - I suspect that 4mm is a more appropriate size. I chose something which looked thick walled on RonR's advice.
8. Appropriately sized jubilee clips
TOTAL: around £120

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First job was to dismantle and clean the rather siezed Forge valve. 'Muc-Off' bicycle drive chain cleaner cut through the old grease super easy. Then install new piston and O-rings as per Forge instructions.

Cut the induction hose to accommodate the T-peice. I made the cut as close to the bend as possible. I initially thought a section of the induction hose would need removing. In the end, it only needed cutting once as there was enough room to just slide it further over the pipe coming from the wheel arch area. I used the jubilee clip to ensure a neat cut.

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Connection to airbox:
Drilled out the blanking plug with a Step drill bit and fashioned a washer (as per lotusflasherman Phil's method) curved on one side to conform to the inside of the airbox (see final pictures). I found that clamping the hose to a cutting board allowed me to cut the curve more easily.

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Simply assemble everything and install. Removing the airbox to drill an appropriately located hole is a fiddly job done from underneath - jack up the front left of the car - observe safe jacking procedure - other posts show how to do this. My airbox is now held with just 3 of the 4 bolts as the right most one is such a pig to get to I didn't bother replacing it after the first time I had it out (added lightness). I was not able to position everything in a way which allowed me to use more of the straight 25mm hose for the reciculation connection to the airbox. Phil lotusflasherman seems to have positioned things so that this was possible. I found that I needed some flexible pipe in order to connect things up. The kit was initially fitted just venting to atmosphere whilst I ordered some flexible 25mm hose. This at least allowed me (and anyone within half a mile) to hear that it was working. I can confirm that it was LOUD! With the recirculation hose fitted, it is just audible.

I located the spare vacuum connection on the inlet plenum as per RonR's advice and connected the vacuum hose there. (No spare pictured here as it is post installation). It will have a rubber cap held on with a clip.

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[Geordie]

Hi
I’ve been following this thread ,and as an older person curious for the reason to fit one of these ? What are the gains etc or is it purely a noise thing
Geordie

[Squirtydog]

There's no noise associated with a recirculating system as it dumps the air back into the air intake box. The idea as I understand it, is to prevent the back surge of pressure on the turbo compressor when you come off the throttle to change gear. The principle is that this back pressure effectively tries to stall the compressor suddenly and may lead to wear and possible eventual failure. I say principle, as the more I read around the subject, the more it seems that the jury is out on the demonstrable degree of wear/stress. As I have upgraded to the Everest chip I felt that this was a sensible move. Others will probably be able to add more insight.

[Fredjohn]

Not all dump valves feed into the airbox. Those that don't create a whooshing noise, so beloved of Astra driving chavs!

As the back pressure on the turbo blades is released by the dump valve, the turbo keeps spinning rather than stopping. So when you accelerate again, the turbo is still spooling and will take less time to reach effective boost levels. You will therefore get a quicker response on acceleration. It may be marginal for normal driving though!

Well, that's the theory.....

[KenS]

If you have access to a 3D printer, the attached files provide a 1inch stub pipe that fits to the standard airbox, its base is contoured to fit the radius of the airbox side wall. Would recommend using PETG filament since it has a higher temperature rating than most.

pic1.JPG

pic2.JPG

pic3.JPG

Note - it looks like the contour of the base is wrong but it is ok, viewed 90 deg futher round and it looks OK!

AirBox 1inch stub SLDPRT Files.zip

Due to being too large, the STL files have been compressed with 7Zip and again with WinZip, 1st to get the size down and 2nd to give an allowed file type!

stub STL_2.zip

nut STL_2.zip

washer STL_2.zip