jonwb

OK, admittedly this ain't exactly like I just rec'd a 4.1L build kit, but it will be nice to check a few things off the list.



Ty will know what these parts are just by looking at the part numbers on the boxes But for everyone else, that's a pair of new vacuum actuators for the exhaust system. Since I bought my car last spring my valves have been stuck in 'always open' mode... which leads to an unpleasant drone between 2k-3k RPM (the side mufflers are effectively always bypassed).

The actuators on my car had apparently been hit from the bottom at some point. As can see from these pics the actuator and the bracket had been 'tweaked'.





Both sides basically looked like this. So ordered a new pair of actuators and straightened out the brackets. Here's some before and after pics of the brackets:







While I was waiting for the parts to arrive I wired the flappers to be in 'always closed' position. So basically the drone is gone, but it's quiet all the time which makes me (and the car) sad. Hopefully I can find some time this weekend to get the new actuators in there and have the exhaust working like it's supposed to.

997s07

Have you noticed a drop in torque at the higher RPMs with the valves always closed?

jonwb

If you look at this link (towards the bottom of the page), the data would say having the flaps always closed will have a decent (negative) affect on HP & torque.

http://sharkwerks.com/porsche/techni...at-laguna.html

I've had my GT3 since May. I haven't taken it to the track yet (not 'til coolant lines are pinned / welded), and I'm still a bit gobsmacked by the speed of the thing. So, could I notice the reduction in power? Not really. On the street you really can't even get to the back side of the tach in 3rd gear, and 1st and 2nd gear are still pretty much berserk...

I really do miss the sound though. While the drone is / was annoying, if I could only have the exhaust either always loud or always quiet, I'd pick always loud all day. The sound is part of the character of the car, and it does loose a bit of that character when its this quiet. Luckily, thanks to the clever work of the engineers I don't have to make that choice.

997s07

It's hard to drive these cars, especially the .1, on the street since the revs have to be around 4K. I never get out of 3rd gear or 4th gear. These cars are a handful.

If you want loud, get the cargraphic unsilenced center exhaust. It's loud and roars like mad. I swear it sounds like an RSR to me.

jonwb

You mean this one?

http://www.cargraphicts.com/en/produ...-rs-mk1-36/01/

Actually, don't tempt me! LOL Aside from this little fix I'm working on, I really want to get the coolant lines done first before I drop money on exhaust bits. Knowing basically what it sounds like when the side mufflers are bypassed due to my flaps being open, it must be nuts when there is basically no center muffler there at all

997s07

This one (non silenced):





Keep the side mufflers. Get this badass. You'll scare the city. In a tunnel it sounds like an F1 bark. The 3.6 is higher pitched and revs faster than the 3.8 (sold my 3.8 for the 3.6).

Don't want to tempt you.

Edit: Posted Picture

jonwb

Well, quick update... I installed the new vacuum actuators about a week ago.



Then I promptly had to go down to Mex for work. So after returning yesterday, I drove the car to work today expecting to hear no-drone AND loud(er) fun mode. No joy... It basically sounds like it did before I removed the damaged actuators. Nice to have the growl / wail back, but its not nice to have the drone back.

I know the new actuators and exhaust flappers move freely so they must not be seeing a vacuum. Perhaps its my solenoid. Or the line going to the solenoid... More digging.

jonwb

Mystery solved... I guess that guy that had the car before me liked the drone. As you can see in the pic below, he had the output to the solenoid capped and the tube that goes to the vacuum actuators plugged. Here's before and after the fix:







Just for the sake of curiosity I stuck my gopro under the car to grab a bit of video confirmation of the fix:



It's interesting how it works with the "SPORT" button. Basically as you accelerate the car opens the valves at a lower RPM (compared to "SPORT" off). In normal driving (under 3k RPM) the valves are closed regardless of the "SPORT" setting. As you coast to a stop with "SPORT" ON however you can hear the exhaust note change just as you come to a stop as the valves are opened again. Basically giving you a louder idle when in "SPORT" mode. Then as you start to drive, the valves close again until / if you reach the RPM threshold where they'll open again.

Well... one project completed. Many more to go.

Speeds5

I think the guy before you had the side muffler delete done that's why that was hose was unplugged and capped. Common for those that have that mod. Glad you got it sorted out.