Exhaust Bypass Valves - Page 2 - 986 Forum - The Community for Porsche Boxster & Cayman Owners

12-21-2006, 07:06 AM

Well, I would take that sounding exhaust over stock anytime. But Im sure itd get old on the highway so poof, its normal again. I thought about doing that too, where you just bridge pipe to the tip, but then you dont get the option of going back to quiet mode, and you wont be able to make it louder unless you get it entirely redone. And valvetronic exhausts are sweet, ive seem them for $10,000 for an M3. http://www.vividracing.com/catalog/product_info.php/products_id/8147 That ones only 7 grand, what a bargain. They sound the best out of anything ive ever heard though. http://www.kreissieg-usa.com/video.php?video=m3_3.mpg&desc=Video%203

Heres there boxster exhaust. http://www.kreissieg-usa.com/index.php?page=detail&brid=3&mid=48&cid=78&oid=&pid=102

And a video. http://www.kreissieg-usa.com/video.php?video=bx060113tuka02.mpg&desc=F-1%20Mode%20Highway%20Pass%20By

kenkamm · 12-21-2006, 01:35 PM

Quote:

Originally Posted by z12358

The Box on that video sounded like crap.

I thought it sounded awesome. To each his own, I guess.

kenkamm · 12-21-2006, 01:48 PM

Quote:

Originally Posted by z12358

I feel many people are not really familiar with what goes into designing a complex acoustic system such as the exhaust.

I did some research on exhaust acoustics when my buddy John and I put together a very simple exhaust to try to shed some weight and get a little more volume. It did have mufflers but they were the straight-through type. We found it resonated very badly at right around the RPM you cruise at on the highway. He took it off after a few days. It wasn't very loud at all, except for at that resonant frequency- where it was unbearable.

What I found in my research is that the straight through mufflers generally work better at high frequencies, which explains why it wasn't that loud at redline. I also learned some fairly simple formulas that could be used to determine the length of an exhaust that would be needed to cancel such a resonance. I forget the exact numbers now, but it was something like 7 feet per side. We found some pictures of a Boxster muffler cut open, and we could see the path that the exhaust followed as it went through. Well I'll be darned if the path length for the stock muffler wasn't very close to what we had calculated. It uses chambers to route the flow back and forth to add length. I'm sure there's more to it than that. BUT, we still plan to hack together another exhaust as an experiment, and run the pipes left to right and back to get the length we calculated.

We also found some evidence that this would work on some Mustang forum. Some guys had used this formula to create a resonance canceling T-pipe or an exhaust pipe of a particular length, and had surprisingly good results.

Acoustics are certainly complex! But the application to a simple exhaust for a car might not be that bad.

Cheers,
Ken

djomlas · 12-21-2006, 03:01 PM

i get on the highway like no joke 5 times a year, so i really dont care about eh resonance that you guys talk about that happens during highway driving

djomlas · 12-21-2006, 10:30 PM

btw, how long does it take to get the exhaust off?

kenkamm · 12-22-2006, 09:40 AM

It's not just the highway cruising. Every time you accelerate through that RPM range, you will cringe.

Getting the exhaust off is a pain because access to a few of the fasteners is difficult, unless you take the bumper off. It probably takes 20 minutes or so the first time. John V, correct me if I'm wrong, you were the one doing the wrenching and swearing.

12-22-2006, 09:57 AM

Holy crap guys, For me it was 1 day delivery. I just got them and he shipped them yesterday. I will have them put on tomorrow. They look really high quality and durable. I just need to figure out how to run the wires from the valves to the cabin. I took out all the carpet in my trunk so its all bare metal. I see where the 2 O2 sensors come into the trunk, and I can get the wires into the trunk no problem it looks like. But how do I get the wires from the trunk into the cabin? I see a gigantic mass of wires running through the wall with some sort of gasket that I dont know how to get out. Any help would be appreciated.

12-22-2006, 06:25 PM

I finished installing everything, except the welding of the valves. What I did was take all of the trunk carpet out, everything. Its pretty simple, no biggie. Then you just lift up on the O2 sensor grommets (they are only in there by friction fit), and you get underneath the car and push the wire through where the O2 sensor wire goes (not hard at all, its really close and the opening is big, but not big enough to fit the big end through). Then you pull like crazy on the gigantic grommet that leads torward the engine, ok, your done with the trunk for now. Put your car in service mode (super easy), and if you want, you can use a grabber or screwdriver to push the wires through to the engine bay, I waited a couple steps though. Next, you undo 4 plastic "nuts" that hold the carpet on the firewall and take the carpet out. Undo 9 bolts and take the metal sheild off. Now take a chisel and punch a slit into the grommet that leads into the cabin (about a half inch will do). This is when I pushed the wires though into the engine bay. I put some heat sheilding over the wires just in case (they run directly the same path as the shifter cables) and pushed the wires through the slit in the grommet ( felt like giving birth to a plug, its pretty tight, but I could have made the slit bigger). Pull all your extra cable (exept what you need to reach the valves) and begin to slide it underneath the console. You need to push kinda hard to get it to be under there. Run it all the way to the bins (you will have very little cable left, seriously, just enough to reach the button). Now you can start on the switch (I used the switch it came with, but I might update to a porsche switch to go in the center console by the ashtray, thatd be sweet), I put my switch in the batwing. You need to dremel your way very carefully, it took me a while to get it right. The way the switch is, you need to remove all the connectors that were in the switch to get it in the hole you cut. So remember where the wires went! Once you get your switch to fit pop it in and reconnect the wires. I used inline wire taps to get power from the cigarette lighter. I had to remove my cd player because I left my tools at college (my torx bits), if you DO have torx bits, the 100% easier way to do it would be to undo the 4 torx screws holding the enitre assembly in place (take off the cover to the side, they hold the lock button, ect..., and you will see 4 screws, once they are out you can take out the entire thing), then just run the wires from the cig lighter down the back of the console and pull it through where the bat wing went. Use butt connecter to connect it to the switch and push it all back into the dash, and you are good to go. Put everything back together (except the trunk carpet, you want the muffler guy to be able to get how much cable he needs). I pulled the wire up to the O2 sensor grommet so it will not be in the way when I drive to the shop tomorrow.

I will take pictures of the install and some sound clips and video. I just need to figure out how I can upload them so you guys can see it.

12-23-2006, 12:02 PM

RandallNeighbour · 12-23-2006, 12:12 PM

I sure hope the heat near that wire near the cat doesn't cause anything to melt.

BTW, the Utube files don't seem to be available.

12-23-2006, 12:18 PM

I put heat sheilding around the wire like the sheilding around the muffler so it should be good. Ya, I just uploaded them, give them time.

12-23-2006, 12:36 PM

Videos work now, heres the link again.

http://www.youtube.com/watch?v=9ryr05thbvM
http://www.youtube.com/watch?v=vpXhUN6-vsk

Oh ya, I paid $40 cash to get all the pipe cut and welded. Pretty good for 2 "Y" pipes and install.

RandallNeighbour · 12-23-2006, 02:30 PM

Sounds LOUD.

Just drove my box with Che's headers and aftermarket exhaust and I don't think I'd want it any louder than I have it now. I draw as much attention driving down the road as any ricer that's floorboarding it. Difference is that when they see me they keep their eyes on the car.. the ricer is always ignored

yfz/700R · 12-23-2006, 03:08 PM

Quote:

Originally Posted by boggtown

Videos work now, heres the link again.

http://www.youtube.com/watch?v=9ryr05thbvM
http://www.youtube.com/watch?v=vpXhUN6-vsk

Oh ya, I paid $40 cash to get all the pipe cut and welded. Pretty good for 2 "Y" pipes and install.

is that a G-FORCE on your winsheild in the 2nd video? with the open exhaust i assume you got a little more top end?

12-23-2006, 04:18 PM

Ya, its a G-Tech, I havent used it to measure runs yet. I will soon, but its hard to find a place to do it.

z12358 · 12-23-2006, 04:48 PM

Quote:

Originally Posted by boggtown

Videos work now, heres the link again.

http://www.youtube.com/watch?v=9ryr05thbvM
http://www.youtube.com/watch?v=vpXhUN6-vsk

Oh ya, I paid $40 cash to get all the pipe cut and welded. Pretty good for 2 "Y" pipes and install.

Sorry bogg, could be just my laptop speakers but that sounded just awful. If I heard that sound without looking at the car, Porsche would be the last thing I'd guess. But as we all say here, I'm happy if it makes you happy.

Z.

12-23-2006, 05:41 PM

No, its the camera

David_J · 12-23-2006, 08:10 PM

Sounds similar to what mine did when I had nothing but the headers on. Very loud and raspy. For the 5 minutes I drove mine like that, there was definately a loss in power.

djomlas · 12-24-2006, 09:06 AM

im curious to see how long the motor will last, i remember the other manufactorers had problems with those blowing up fast, and people were replacing the motors with those out of hairdryers and similar things like that.
hope this one holds up, it would suck if the mtor blew at full open

12-24-2006, 02:06 PM

I did some drive bys today. I think it turned out pretty good. I used the same camera so its not the best. I have other videos, I will upload them later, with the valves half open, full open, and 1/8th open.

http://www.youtube.com/watch?v=08-uX9z_Rg4