FABSPEED MOTORSPORT | GT4 Valvetronic Exhaust
02-04-2016, 08:33 AM
#61
That was my theory as well. When you open the flaps, that means you remove all vacuum from the system (they are open when there is no vacuum). So why is it that they close at high RPM? I thought that at high RPM the system loses vacuum and closes the flaps but that is not how it works. My other theory is that the flaps aren't perfectly horizontal when they are open so at high pressure they are somehow pushed down and closed by the exiting exhaust fumes. Not an expert and don't know if that makes sense, but I'm troubleshooting with fabspeed now.
I think you are in the right path and with Fabspeed help should be able to solve this. Question...how did you disabled the valves? Just removing the vacuum line? Do you still have the problem with the valves disabled?
02-04-2016, 11:32 AM
#62
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Removing the vacuum line would throw a CEL, so not a good idea. I removed the clip and disconnected the little arm that controls the valves.
02-04-2016, 11:40 AM
#64
I am finally picking up mine today - with a recently manufactured unit. Hopefully will have videos from TWS this weekend, compared to a GT4 without (assuming they show up).
02-04-2016, 02:46 PM
#66
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Originally Posted by bhgt2
Removing the vacuum line would throw a CEL, so not a good idea. I removed the clip and disconnected the little arm that controls the valves.
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02-04-2016, 08:01 PM
#67
02-04-2016, 08:10 PM
#68
The thing with the valves is that is not either 100% bypass or quiet mode. When you open the bypass you still have exhaust gases going through the regular muffled path....which does have influence on flow and sound. I always have my PSE ON so that's how I reasoned going without valves.
02-08-2016, 12:44 AM
#71
Super happy with the sound and volume. I had people coming up to me all weekend asking about it...it sounds damn fine.
Not great quality vids, but you will get a sense for what it sounds like full boil. I threw a 997.1 Cup car in there for reference.
A hot lap - the mic is mounted just below the rearview mirror. What it sounds like from the drivers seat essentially. No canbus connection, so no throttle, brake or rpm. Also need to adjust the rear camera a little higher....this was first weekend out in it, still some bugs to work out.
Not great quality vids, but you will get a sense for what it sounds like full boil. I threw a 997.1 Cup car in there for reference.
A hot lap - the mic is mounted just below the rearview mirror. What it sounds like from the drivers seat essentially. No canbus connection, so no throttle, brake or rpm. Also need to adjust the rear camera a little higher....this was first weekend out in it, still some bugs to work out.
02-08-2016, 08:47 AM
#74
That fly-by sound is awesome!
You have the CG headers right?
Getting now anxious to get my exhaust system....
You have the CG headers right?
Getting now anxious to get my exhaust system....
02-08-2016, 11:44 AM
#75
Cargraphic sport headers
I'm still getting the fabspeed install finalized - they require a vacuum booster tank to actuate the valves properly to bring the mufflers into the pathway. I did not install this because I got the exhaust long after ATX had pulled apart the trunk to install the roll bar. I didn't want to go to the trouble of yanking parts of it and the interior out again - so no tank. For the brief times I drove around in quiet mode, it was louder than stock, but it was not resonating at cruising RPM (I call it "Drone" when you have a resonance mode in the exhaust system that makes it louder at cruise RPMs). With them open - yes of course, it's basically a straight-pipe at that point. The whole point of a muffler is to pull out resonance modes from the exhaust system. If you worry about loudness or drone, any exhaust is probably not going to be as good the the factory unit - Porsche did a great job with it.
Yes, I liked their longer-tube design, and started a relationship with John at BGB before I had talked to Fabspeed.
I'm still getting the fabspeed install finalized - they require a vacuum booster tank to actuate the valves properly to bring the mufflers into the pathway. I did not install this because I got the exhaust long after ATX had pulled apart the trunk to install the roll bar. I didn't want to go to the trouble of yanking parts of it and the interior out again - so no tank. For the brief times I drove around in quiet mode, it was louder than stock, but it was not resonating at cruising RPM (I call it "Drone" when you have a resonance mode in the exhaust system that makes it louder at cruise RPMs). With them open - yes of course, it's basically a straight-pipe at that point. The whole point of a muffler is to pull out resonance modes from the exhaust system. If you worry about loudness or drone, any exhaust is probably not going to be as good the the factory unit - Porsche did a great job with it.
Yes, I liked their longer-tube design, and started a relationship with John at BGB before I had talked to Fabspeed.