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Smart Specific Dump Valve

After working out the best outlet size for a smart DV I consulted the Evilution forum's resident metal machinist and a plan was concocted, then the big guns were called in.

Modification Details

The idea is simple, a normal generic DV is no good for the smart.
 We have to reduce its air flow to suit the smarts tiny turbo.

 A range of ideas were discussed and eventually two solutions were found.
A DV is machined with the correct diameter straight from the factory.
A flow restriction insert is machined to fit either the DV or the tube and bolted in place.

Let's Look At These Options.

A DV is machined with the correct diameter straight from the factory.

So, all we have to do is contact a major DV manufacturer, ask them to make a special
DV for the smart dispite the fact that they probably already sell smart DV kits.
Convince them that their original DV is no good for the smart and that some
random 'know it all' knows the solution... AND get them to listen/believe you.

Let's be honest, it all sound very unlikely doesn't it?

I couldn't have been more surprised when Peter from Forge Motorsport emailed

me to say that he had made one for me to test and the next day, there it was.

This end is exactly the same as the DV they have always sold for the smart.

This is the business end, the newly machined 12mm purge inlet.

The DV came with a fitting kit which includes:

38mm/25mm/38mm silicone T piece
500mm of 4mm ID silicome vacuum tubing
5mm barbed plastic T piece
an uprated spring
2x 35-50mm jubilee clips
1x 25-35mm jubilee clip
3x black plastic zip ties

So you can see that there is nothing left out, all you need to do is fit it.
Forge have their
own instructions but I will add my own fitting guide to the site when
it is done. I will fit it and try it out and let you all know how it performs in due course.

Option 2

A flow restriction insert is machined to fit either the DV or the tube and bolted in place

Because there are so many DVs available, each flow restrictor is made specifically
for your DV. The metal insert takes the inlet size down from around 25mm to 12mm.

My Smart Specific Sequential DV

I won a Wiltec sequential DV on Ebay and had it sent straight to Chalky for 'correction'.

As you can see, the outlet that the DV bolts over now has a 12mm flow restrictor
bolted directly into the neck. With the DV in place the bolt is secure and so is the adapter.

Does It Work?

Of course. The DV still makes the noise you expect but now the turbo isn't struggling and
the gear changes are as they should be. So far, no one has had a bad word to say about it.

Initially there were 3 main companies that wouldn't fit a DV because
they knew the damage that they can cause to the smart engine:

Smartarse Design
BIG Performance

What Do They Think Now?

Rob from Smartarse Watford agrees the idea is sound.

Kate from Wellsmart said
'I've driven Chalky's car with & without this mod, from someone who really doesn't get the
sneeze box, trust me it does feel different! Seems to have smoothed his gear change out'.

Ian from BIG Performance said 'In theory is should work'

Do yourself a favour, get yours converted, send the pics and let me know what you think.

Chalky can be found on the OnSmart 
forum or on Ebay.

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