In previous segments of Project 987.2 Cayman we worked on our suspension and brakes to prepare our chassis for more power. Now it’s time to attack our 9A1 engine to get more naturally aspirated power and better reliability in track use. In this segment we will be replacing our factory exhaust system with some cool parts from Fabspeed Motorsports. The stock factory exhaust is very heavy, a lot of this is because in this cars case, being a mid engine, it must quiet the exhaust note in a very short distance. This means big heavy mufflers. Since this is a track focused car, being quiet isnt much of a priority but adding power and getting rid of weight is!
The factory exhaust manifolds are also heavy and not the best suited for making power with a lot of neck downs and flat spots in the tubes for chassis clearance.
To install our race exhaust system we first remove the under chassis braces that connect the cross member to the unibody.
Next we remove the triangular engine plate. As a note, do not put the cars weight on its wheels with these braces off, it can affect the alignment or even damage the subframe if you attempt to drive the car with these parts not installed on the car. If you accidentally put the weight of the car on its wheels, the alignment must be checked afterwards.
Next we removed the oxygen sensors from the manifolds and the exhaust. It’s easier to do this while these parts are on the car so you can get more leverage on them.
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I’m sure there’s a reason, I’m just curious why the vacuum actuators weren’t placed closer to the muffler bypass T-section.
That is about the only place they could be to divert the flow to either though the mufflers or the bypass.
The length of pipe leading up to the bypass valve probably works as a Helmholtz resonator to additionally reduce drone. Or not.
This is my thought as well, I wish I had time to experiment with Helmholtz resonators on my own cars, but seeing little stubs like this absolutely makes me think that’s at least part of the reason for their placement.
I’d imagine with the length being so short (12-18″?), it might help cut out rasp more than drone, but it should provide some effect without hurting exhaust flow (and power) too much at lower loads….
The thing is the bypass is open on both ends so it’s not a Helmholtz resonator. Having two exhaust paths of different lengths does change the frequency and possibly cancels out some frequencies though and the exhaust isnt as loud as you would think when its open
Keep us updated on this project 987.2 build.
Curious question, so, when you are performing the modifications to your Cayman, is this a road legal car? Or is this track use only? I would like to think it’s a track only car not to be used on the road?Iif not, the removal of the catalytic converter would be a big EPA issue?
It is a track car. It says so in the articles about this project and twice in the first paragraph in this article.
But you’ll be comparing it to the GT4 power-wise…which still has full emissions?
A bit of apples to oranges comparison, no?
This is a track car, not a street car. Plus a GT4 is tens of thousands of dollars more. A GT4 Clubsport is over a hundred thirty thousand more and we think we can come very close to this, perhaps exceed it in some aspects.