Exhaust Bypass Valves
 

Hey guys, I just bought these electric bypass valves and will be doing a write up along with dyno tests over the next couple weeks. I bought the valves and will have them installed within a week or two. I contacted PorscheDoc and got the low down on doing some dyno runs. So everything is falling into place. I bought dual 2 inch valves from Charles (http://www.badlanzhpe.com/index.html) and they are the best value out there if you want sound and maybe some top end (we will find out when I dyno them). I spent a total of $270 and that is a drop in the bucket compared to a $1000 muffler, and it will be louder and resonance free... if I want it to be. Any feedback will helpful. Let me know what you think. :)

Expect Updates!

Exactly where do you plan to put these?

I'm looking forward to this!! Having not wanting to drop thousands on an exhaust and not wanting to take a chance on resonance and the constant drone of a cat-back type system this can be the perfect solution! Quiet or loud depending on the mood of the moment. My only concern would be the placement in the exhaust system (ground clearance) and the motors freezing/breaking in the "open" position. As far as gains in power...I doubt it...like all the other exhaust systems on the market this would be great for sound only... :cheers:

Since the pipe to the muffler makes a U after the cat, we were going to cut that section out and add a pipe to make it a Y pipe. The actual vavle would be inside of that U. There will be plenty of space considering the valve is relatively small. I plan to just run the wires where the stock O2 sensors run into the car.

So, to be clear, you're going to have a 2" straight pipe which can be used to bypass the muffler using your valves?

I can tell you from experience that a 2" diameter straight pipe positioned right there will be loud. And incredibly droning. :D

Wow, looking forward to it! Good luck!!

Heck yes its gonna be loud. :D But droning can be easily fixed with a flick of a switch. Its almost all for the sound, but if I get any top end it will be of good use at the track. Heres a picture of the planned layout.

It would be a heck of a lot cheaper and easier just to pull the U tube out from the muffler when you get to the track than go through all you're doing now IMO.

But how will I do that while driving next to a fart can honda and blow them away with my awesome sounding engine? I want a louder exhaust like 98% of this forum, by getting bypass valves, I can get loudness, mediumness, or quiet instantly and keep the woman happy or open the valves as soon as she gets out of the car so I can scare small children.

I can't wait to see the outcome of this project. :cheers:

The only problem is that it doesn't really sound good when the muffler is off. It's just boomy and obnoxious. Given that there is no performance increase at all to running straightpipes (with the possible exception that with real straightpipes you can eliminate the weight of the muffler) it doesn't seem worth it. But, your car.. knock yourself out!

so you want your car to sound louder than a fartcan on a honda? am i getting this right? and y are you even trying to impress honda boys anyways...they already got it bad :cheers:
there is a difference b/w a nice sounding exhaust that is pleasant to listen to, and annoyingly loud.

This is true. And I can tell you from experience that a Boxster with no muffler sounds absolutely terrible. When I was building my custom exhaust I tried it. Not good.

It wont be 100% without a muffler, there will always be flow through both pipes, just more through the valve. If it does suck then I can just open it a little bit like the PSE bypass.

When I took my car in to get the exhaust installed, I removed the 2nd cats prior to dropping it off. OMG, is was crazy loud. Did not sound good at all. Having the valve that you can adjust should make it sound better as you can control the flow. Since there was no backpressure, the car drove poorly. That was the worst 5 minute drive I have ever had in my Boxster.

Ferraris use this valve type technology. The sound of the valves slamming shut sounds kind of cool. Like a shotgun! You can hear this on FabSpeed's web site in the Ferrari section.

I have been looking at ordering one of these

http://cgi.ebay.co.uk/Porsche-Boxster986S-3-2-986-Sport-Sound-Muffler-Exhaust_W0QQitemZ290056062535QQihZ019QQcategoryZ38 786QQcmdZViewItem

Might be a different way of installing the valve in the bypass pipe. The video shows what effect the bypass has.

how much would a muffler shop want to add these to a stock exhaust? its just 2 pipes...
i may just look around, i really liked that sound clip, no reason to pay all that money for one already made IMO

Yeah I thought about that too. There is a guy here who did it himself.

http://www.ppbb.com/boards/ppbbphp/showflat.php?Cat=&Board=ARCHIVES&Number=1067764&pa ge=8&view=collapsed&sb=5&o=7&fpart=1

The Box on that video sounded like crap.

I feel many people are not really familiar with what goes into designing a complex acoustic system such as the exhaust. It has been years, but I remember how in high school Acoustics, we used to build Acoustic curcuits equivalent to electric curcuits. The idea was that the formulas describing the physics (dynamics) of sound waves (air pressure) in enclosed spaces are equivalent to the math describing the current in passive electric RLC (resistor, inductor, capacitor) circuits.

That math is not simple, and far from straightforward. You take one resistor out of an electric circuit and the circuit will stop doing what it was meant to be doing. There are issues of frequency bands and filters, harmonics distortion, and resonance. When all that gets combined with the physics of the car that surrounds the system, it gets even more complicated. Pockets of resonance (amplification of a certain frequency band) can fall right on top of the frequency bands defining the car's structure and rigidity -- and that's when the whole car starts shaking at certain rpms.

I doubt that ANY of the after market exhaust vendors has modeled any of these things the way I'm sure Porsche has.

My point is, these exhaust mods are not trivial, and sound level is not even close to being the most important factor to consider.

Z.

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=&pi d=102

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

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

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

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

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

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. :)

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.

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.

Done. It sounds amazing. Just fantastic. A real racecar sound. Heres some pics and video. I used my camera with the video function, so its not the best quality sound. It sounds a lot better when your actually driving. I will get some flybys later. I prefer to only have the valve open about an 1/8th or 1/4, its plenty loud and you get a "tighter" sound.

http://www.youtube.com/watch?v=9ryr05thbvM
http://www.youtube.com/watch?v=vpXhUN6-vsk
http://aycu16.webshots.com/image/7815/2004515622262479657_rs.jpg
http://aycu32.webshots.com/image/7351/2004582723881596698_rs.jpg
http://aycu06.webshots.com/image/7165/2004575913491526492_rs.jpg
http://aycu17.webshots.com/image/7096/2004550235778225640_rs.jpg
http://aycu30.webshots.com/image/8749/2004594263172633378_rs.jpg
http://aycu14.webshots.com/image/6533/2004505873849717705_rs.jpg
http://aycu03.webshots.com/image/8922/2004574680502544669_rs.jpg
http://aycu10.webshots.com/image/8089/2004528406078184603_rs.jpg

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.

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.

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.

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 :)

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?

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.

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. :cheers:

Z.

No, its the camera

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.

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 :)

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