Sunday, November 30, 2014

Porsche Cayman S Exhaust Outlet Modification

The Porsche Cayman, especially the early ones, have a rather bad design for the exhaust outlet.  The 2 muffler outlets point directly toward each other.  Then they flow into a T as if a plumber built it.
After that, the exhaust goes into a restrictive decorative tip.
Notice the tiny holes for the exhaust to flow out here.

I finally replaced that nasty exhaust T on the Cayman S.  I bought 2, 2.5" ID 90 degree mandrel bends from Summit Racing (part# 670176 ).  Total cost $40. These bends are tight with a 2.5" radius.  Yes, tight is bad but still better than a T. I removed the passengers side muffler assembly for access and cut the muffler outlets down to about 1.5".  I cut the bends to fit snugly on the muffler outlet.  It just so happens cutting the long side of the elbow left just the length I needed for the tailpipes. I was even able to reuse the clamps from the original T.  I also cut the factory stainless tip from the old tailpipe and attached it (sorta) to the 2 tailpipes.  It looks stock from a distance.  I doubt this really made a very big difference but honestly it does seem a bit crisper at high RPM.  Could just be in my head though.  It just looks like it flows better.

For now I removed the inside of the decorative tip and placed it over the 2 pipes.  It looks basically stock until you look closer.  I will likely replace this with 2 stainless exhaust tips later.
Here is where I had to cut the muffler outlets to fit the new pipes.
Here is where I cut the bends.

We did a similar modification on a friends 981 (2013 Boxster).  It looks like similar tubes are also available in stainless steel.  The part number for those is VPE-13040 ( ).  The bend radius is 3.5" instead of 2.5" thouogh.  We did install these in a 2013 Boxster.  It was tight.  We had to cut the tubes so the radius was abut to the weld bead on the muffler outlet.  It did fit though.  The milder bend will flow better.  The 981 had more space between the muffler outlets than the 987.1 did.  I don't think these would work on the 987.1.

Update 7/5/2015:
I purchased some inexpensive stainless steel tips from Advance Auto and modified them to install over the pipes.

These tips were only $15 each.  I had to remove the attaching hardware and cut a slit along them.  Then I used a pipe expander to open them up enough to slide over the pipes.  They are a tight fit but I can still adjust them as needed. I used simple worm clamps to retain them.

We redid the 981 Boxster as well.  He bought the sharper bends I had and the same tips.  His car looks like this now.

The pipes setting below are the stainless ones with the milder bends.

Porsche Cayman S Intake Modification

This is how you remove the noise regulation required intake restrictor.  The snorkel is intended to increase the air speed under full throttle to prevent induction sounds from exiting the vehicle.  However, this does add some restriction and the induction sound is fantastic and should be allowed to be heard.  It only makes a difference at about 3/4 throttle to WOT.  On the 987 there are a few parts to this.  The snorkel tube and the plate behind the grille.  On a stock car, you can only see a black plastic plate behind the grille.

1) remove the outer grille (pry 2 clips with screwdriver)
2) remove the grille support (5 clips)
3) remove the blocker plate (a few clips) and discard
4) remove air filter to access inside of snorkel.
5) pry the bottom of the snorkel tube to release catch and pull snorkel out through grille opening.
6) reassemble.

Reducing the air velocity will help reduce the amount of water that is pulled in with the air during rain. The reduced restriction might give you a tad more power at WOT near redline.  The biggest difference is probably the lovely induction sounds you can now experience.

This does come with a risk!  If you are driving in heavy rain, or any other situation where large amounts of water could enter the air intake, you could risk damaging the MAF sensor.  One of the functions of the OEM setup is to remove the water from the air stream.  The modification described above does make it more possible for water to get past the air filter and damage the MAF.  In very extreme cases, if you ingest enough water, you can hydro-lock the engine which can cause catastrophic damage.  Even with the snorkel and the outer plate removed, the air cleaner still has good protection from these risks. The risk is higher at high air flow too so if you encounter heavy rain, avoid heavy throttle.  I am thinking I will make an active water separator device later to mitigate this risk completely. You can also keep the panel in the car and if you are going to drive on the track in heavy rain, pop it back on.
Snorkel removed. That black plastic piece inside the oval is a cover on the tip of the air filter to prevent water from getting on the filter element.

Air filter

Inside airbox
Grille pieces
This shows the grille in place and the snorkel still installed.I removed the snorkel later.
With grille and panel removed

Here is the intake sound after the modifications and a K&N air filter.