Wednesday, January 21, 2015

DIY -- Porsche 991 911 Exhaust Sound Hack

(originally posted on 6Speedonline.com 12-02-2014)

I was tinkering-around the garage the other day, and thought the following might be of interest to members who have had similar thoughts, or just curious about the vacuum lines to the "S" standard and PSE exhausts. 

The following Mod will eliminate the function of the Carrera S standard exhaust "flap" (well, at least one of them - see my note at the bottom of this post). The result is a sound that is deeper, a bit of drone, but definitely "on all the time" whether in standard, Sport, or Sport Plus modes.

This is a really simple DIY. Takes about as long as you need to get the rear of the car up off the ground, lay on the floor, and reach up to pull the vacuum line off. I spent about 10 minutes "exploring" and taking a few pics that follow.

Note that if you don't have a Carrera "S" car, or car with PSE, you can't perform this hack.  The base 3.4L Carrera does NOT have a vacuum system controlling valves to the exhaust....

STEP 1: Obtain some Vacuum hose end caps. You can pick-up some from your local auto supply shop (Pep Boys here in PA for me). I think these cost me $1.97 and come in variety of sizes. I happened to know that my stock vacuum hose was replaced recently by the dealer with a covered hose, so I needed a larger diameter cap opening than you might -- so getting a variety pack is the best way to go.

Click the image to open in full size.

STEP 2: Raise the rear end. I pulled my car in the garage and up onto my Rhino Ramps - then put the E-brake on and chocked the front wheels so the car wasn't going to move on me! You don't need ramps, but they are safer than a floor jack alone.

Couple of pics on the ramps...

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Click the image to open in full size.

For reference, I have a 2014 C4S with standard, non-PSE exhaust. In this form, the center muffler is different than PSE and non-S cars, but does have the valve controls and vacuum lines. Performing this mod on a car with PSE should be identical, and may sound even better/throatier all the time.

I should also note that I have twice in the past year had one of my vacuum lines separate from the valve, so I was already familiar with the sound effect and so on. The big difference between those times and this mod is that you can eliminate the "Coolant System Fault" or similar warning that will occur.

Before moving-on to the next step I should state the obvious -- Let your car cool-down before you start putting your arms and hands into the areas round the exhaust!! My car had been sitting for hours, and only started long enough to get on the ramps. Even still, I wore mechanics gloves and had on long-sleeve heavy shirt -- the space around the exhaust valve is tight and you will definitely come into contact with some hot surfaces! Please be careful! And while you're at it - wear some eye protection. You are looking straight-up into the bottom of a "dirty" area of the car and last thing you need is a bit of dust or worse falling into your eyes!

STEP 3: Locate the passenger-side exhaust valve. Approaching the car from the rear, get down flat-on-your-back on the floor behind the rear wheel and look up. Your vacuum line is likely clear in color, but could be other colors. I've seen white, blue and green. Currently, my vacuum line is clear with black insulating material - see pic below....

Click the image to open in full size.

The hose just slips on the exhaust valve. So a gentle tug or two and the line should be free....

STEP 4: Pull off the vacuum hose from the exhaust valve. Here you can see I've pulled it off and it is just hanging...

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STEP 5: Place a vacuum line end cap onto the vacuum hose end - use a cap that fits securely to the end of the hose. Too loose and it will fall off....

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STEP 6: Tuck the "loose" vacuum line up and out of the way so that it doesn't come into contact with any heat sources, etc.

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Final Pic:

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That's it! You are done! You can start the car and immediately you will hear the difference. Drive it and in any mode it sounds better to me. I've driven for several days now like this, and have yet to see any warnings. The trick is to make sure that the vacuum line hose is capped, so the system can't tell that you've disconnected.

If, for any reason you want to replace, just reverse the procedures above. I did just that and it took 5 minutes.

NOTE: The steps above are for a single exhaust valve. Yes, I know there are two, and perhaps performing the same mod on the driver-side line will result in an even throatier sound. But I found that the other valve line is much harder to access from this position. So, if you are up to it you can tackle that one -- or, the alternative is to disconnect both lines at the "T" intersection. You can find this just a bit above the exhaust valve on the passenger side. Pull the feed line from the T connector, and cap that. But again, I found that in my garage, laying on the ground, reaching the T with my big hands was going to be problematic. So, I "settled" for only disconnecting the one 
line....

I would love to hear from others if they've figured-out an easier way to 
access the drivers-side valve, or the T connector mentioned above....

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