How can I protect my Pipercross PX600 C603D air filter?

[John Vine]

My S3 R400D with roller barrels has the C603D Pipercross air filter.  It was new in Sep 2019.  In a little over 1100 miles (that's lockdown for you), the leading edge of the filter has lost its outer layer of foam.  The underlying red foam is intact and the interior is pretty well perfect.  

Of course, it sits in the airstream so is very exposed, but I'm looking for ways to extend the life of its replacement.  An airbox would be one (expensive) solution, but is there another way?  

JV

[Toughie]

Bearing in mind that I don't know what I'm talking about here, but wouldn't an airbox change the pressure pulses in the induction, meaning you should remap?

[John Vine]

It could well do, Alan.  I'd need to check. 

JV

[7 wonders of the world]

Airboxes can and do change the mapping requirements some for the better many for the worst, quite a few fit too snugly over the filters though.

I wonder if UV is the culprit on the utter layer as mine has a hint of red showing too. 95% of my filter is outside searching for that lovely cool air   

 

[L7 FST]

I wonder if Pipercross have recently changed the spec of the foam?

I have a similar problem on my C603D filter, new less than a year ago and, like John's, relatively little used since.

The one it replaced had been on for three full years with much less deterioration ...

[John Vine]

Re #4:  Interesting thought re UV.  But if that was the cause, I would have expected more deterioration on the top of the filter.

Re #5: I wonder too.  I'll send my photo to Pipercross for their comments and report back. 

JV

[rkeywood]

Is the PX600 an oiled filter?  Their website notes it as 'competition foam'. If that's the same as their 'race' filters then I've found they deteriorate very quickly if not cleaned and oiled regularly. The instructions for the race filters are to clean and oil every 1000 miles but possibly needs to be more regular if not used.

[7 wonders of the world]

Mine does feel noticeably more crispy on the top compare with underneath

[John Vine]

Re #7:  That's a very interesting point.  The Pipercross website says:

The PX600 range of filters is developed for twin carburettor or throttle body applications. They are used throughout Motorsport and are supplied as an OE item to the likes of Westfield, Jenvey etc.

The range consists of a filter unit which utilises the Pipercross competition foam, bonded to a ring plate. The filter is a lifetime filter and can be washed and reused, it is a simple process using one of our cleaning kits. This ring plate can be attached (using the supplied DZUS fasteners) to either a tailored base plate or a blank base plate so you can cut the holes to suit your application. 

And their Competition page includes the following:

Foam filters can be washed every yearly service or 10000 miles, meaning that you buy once and aren’t paying for a filter every time you service your car. Because the filter can be washed, it makes it an eco-friendlier option.

We control the level of oil impregnated into our foam, adding just enough to allow the filter to work but not so much that it ever leaves the filter.

My filter is clean, having covered just over 1100 road miles.  Any oil present would be whatever Pipercross applied during manufacture, as I've never washed or oiled it.  

JV

[rkeywood]

Do they feel slightly oily to touch or is it just dry powder? In the past I've had trumpet socks disintegrate like that when stored. The similar FF filters also suffered with drying out and needed cleaning and oiling although the website now describes them as 'disposable'.

The website and instructions in the packet seem to differ. The maintenance slip that comes with the trumpet socks and the FF PX400, that look like a similar media, seems to be generic instructions and lists 'race filter' (1000 miles, maintain and oil), 'oiled filter' (20000 miles, maintain and oil) and 'dry filter' (20000 miles clean and wash). It also says that "Race filters are not suitable for road use!". Nowhere does it say which of the 3 types you've actually got.

Send the pic' to PX and ask them what's happened and how they should be looked after?

[John Vine]

Do they feel slightly oily to touch...

Indeed they do.  I washed my hands then ran them over the foam, inside and out.  There was a distinct oily film on my fingers.

I've never been advised that the C603D is unsuitable for road use, so presumably it would not be regarded as a "race" filter.

Anyway, I've emailed Pipercross, explaining the timescales and mileage involved, and attaching the pic above plus one showing how the filter protrudes from an S3 bonnet.  I'll post up their reply.

JV

[Geoff Brown]

In the 8 years of R400D ownership I am now on my third 603D as the leading edge & adjacent surface ablates to the point where the red inner lining can be easily seen.

I contacted PX about cleaning & lubrication explaining where the filter is fitted. They replied that cleaning with PX cleaner was OK but oiling due to the external application should be avoided, a dry fit best.  A 'light'' occasional vacuuming from the inside would be most effective.

The main in service problem is avoiding the filter when removing & refitting the bonnet as the forward end can come under stress.from the cut out. One just has to flex the bonnet that bit more to clear the filter.

[John Vine]

So, it's not just me, Geoff!  And thanks for the PX comment re oiling.

I've had a closer look at my filter.  This pic clearly illustrates that the black foam layer is separating from the red substrate:

  

This one shows the leading edge.  The foam is crumbly, as though it's denatured in some way:

This one shows the filter in position: 

The cut-out is large as CC cut it to allow for an airbox.  The bottom edge has formed a shallow groove in the black foam (not visible here), possibly caused by sideways engine movement.  Whether that has contributed to the loss of foam isn't clear.  But it suggests that I need to fit some IVA-style trim along this edge.   

PX describe this filter as multi-layered, with each layer (of 3?) trapping a different size of dirt particle.  I'm assuming that the outer black layer traps the largest particles, so I'm wondering if my filter is still effective given that the underlying red and black layers are intact? 

JV 

[7 wonders of the world]

A 'light'' occasional vacuuming from the inside would be most effective.

 

My Jenvey's see to this on every generous application of the small pedal  

[Toughie]

[Ed White]

Any thoughts on this being due to airspeed over the filter eroding it? Sitting in a draught of up to 70 mph I would guess would wear away the foam quite quickly

[Geoff Brown]

Slip stream up to 70mph & over will cause ablation to the black outer layer as I have found with the previous two filters.

Obviously the outer black layer is not designed for that environment ?

[John Vine]

Well, I've now exchanged emails with PX -- very friendly and helpful people. 

To summarize:

They've seen this type of abrasion before but only where the filter has been rubbing on something.  When I explained that the filter was in a large open cut-out, they thought that a possible cause might be road grit and stones thrown up from the N/S front wheel, given that the abrasion was on the exposed underside of the filter.   They didn't comment on the damage to the leading edge, and they couldn't say whether the airstream contributed to the abrasion, mainly because their filters are rarely deployed outside the engine bay.

(Anyone have access to a wind tunnel?)

On the plus side, they assured me that, even with a damaged outer foam layer, the filter would still work ok, although the sub-layers might get blocked more quickly as a result. 

Anyway, I now have a brand new filter, and I plan to experiment with a small plastic guard sitting under the lower exposed part of the filter, and raised up over the leading edge.  I should be able to clamp this between the bonnet and the top chassis rail.

JV

[Tazio]

I have a VX on throttle bodies and have run an exposed ITG filter for the last 8 years and never suffered any damage like that, perhaps its a material difference between the 2 manufacturers.  Perhaps time to change?

[John Vine]

Re #19:

Perhaps time to change?

Good to hear that the ITG seems more durable, but the snag is that the Megaflow mountings look to be quite different to the PX ones.  I certainly have no plans to ditch my expensive c/f backplate!

Edit: Having looked again, maybe the JC50/100B would do the job?  The dimensions are pretty much the same as the PX.  Do the upper three clips match?  And how is the lower edge fixed (I can't see any PX-style tabs)?

JV

[Tazio]

The bottom of an ITG filter has a slot which clips over the bottom edge of the backplate.

[7 wonders of the world]

I looked at ITG having used them previously and they don't offer a really deep sausage (I run C604D) only a deep box filter, also looked at Ramair too.

[John Vine]

Re #21:

Thanks, Tazio.   I asked ITG the same question.  They suggested the JC50/S/100 sausage filter, which would clip onto the bottom edge of my backplate.  They also indicated how I'd need to modify it:

That, of course, is a non-starter.  Why would I want to massacre a tasty c/f part costing £250, and lose the ability to fit the PX filter in the future should I want to?  I've asked them if they can recommend a suitable ITG baseplate to match these dimensions:

JV

[Geoff Brown]

JV - Remember that there is a minimum distance required between the inner face of the filter & the trumpet lip.  From memory the distance is based on the dia of the trumpet intake & the trumpet length.

Would not want to strangle that wonderful 400D ?

I am sure someone will be along shortly with the exact formula...............

[John Vine]

You're right, Geoff.  The internal height of the C603D is 90mm, so there's 55mm of clearance at the centre line of the trumpet.

JV