ruffy

fellow enthusiasts,
I've been toying with the idea of using a solenoid controlled bypass to control an exhaust duct routing waste gas directly out from the down pipe.

granted, it will be extremely loud... but for track usage will be extremely useful. Ruf has created something similar but still routes it through the cats. For my track purposes, it won't really matter. The wonderful thing about having this solenoid is the on/off switch which will be perfect for road usage.
recently, i managed to find someone technically capable of that welding standard and is also familiar with high temp solenoids.

The only problem i forsee is the engine bay being a little too packed to house another exhaust outlet. The other obvious problem is that it may exit too close to the rear tires... again potentially err...not so good. especially with flames popping out occasionally

there are a couple other ways of ducting it directly to the muffler but may facilitate cutting the muffler and making more internal modifications to facilitate this function. In anycase, i'll have the hoisted later to look around underneath.

am i the first guniea pig?

any suggestions, criticisms appreciated.

911/Q45

I'm not real knowledgable on this subject, but don't the waste gates function when you're off the throttle? It seems that the restrictions of the muffler/cat would not matter under that condition. Educate me please!

poorb0yw

Have you looked into the electronic cutouts that the Japanese tuner market is using to run open downpipes? They seem to be getting more reliable in design.
The cutout is pretty much an electronically controlled stainless throttle plate mounted within an exhaust flange that would bolt onto the exit piping.
Size of the external motor and plate it is mounted to is approximately 3"x3"x2".

ruffy

aye sir Princeton,
on the mark again... thats exactly what i'm looking at... only custom fabricated by a shop. i don't think anyone here has tried it... so i'm looking for experience.
Open down pipe would certainly beat any kind of cat or muffler bypass, as the distance to exhaust is much shorter, infact, theorectically at its shortest.
i wouldn't think that the obd 2 will be upset by the setup... my concern is how the extremely hot air will be routed out without upsetting any other components in the already tight engine bay.

Q45,
pardon my imprecise description, what i meant to describe was a free flow down pipe... not waste gate exhaust management

poorb0yw

Hi again,
The experience I've seen is just that they need to be built correctly from materials that can take the heat cycles. So far the cars I've seen running them haven't really been having problem with the motor system itself but moreso with the "door" that opens and closes. Either the pressure or the heat would get to it and prevent it from sealing. The newest versions are using billet stainless steel doors as opposed to the original pressed alloy. The cars will be up and running again soon with the upgraded electronic cutouts. I'll definitely keep you updated on thier reliability. Also they are made for many diameters of piping if you eventually wanted to try them.

Your assumption about the open downpipe seems to be correct. With it running open the cars have been seeing approximately a 20whp increase when compared to going through a full exhaust system.

As for the ob2 o2 sensors going nuts, a way around it might be to run o2 simulators.

ruffy

If my understanding is correct, then i'll probably have to be a little more specific about the materials used in the gate control...

my guess is i dont think it will actually affect the o2 sensors. the cats will be in place only not vented through.

also, just out of curiosity, where do they run the pipes out to vent the hot gases?

poorb0yw

Yep, just watch and make sure he selects the correct materials for the task.

In the case that your o2s will all still be connected I don't see a problem with your ecu picking up a problem for the limited use of the system with the downpipe running open. It takes mine approximately 500 miles between resettings before it even notices that the secondary o2 sensors aren't plugged into the bungs on my car (running straight pipes).

On the little imports they have the open downpipes dumping right under the engine at the center. I guess they figure they only run open when engaging in high speeds so the hot air would be quickly swept away from the area under the car. No problems in years of use. I'd just appropriate a moving cool down time along with the standard few minutes that you leave the car idling in a standing position before shutting it down.

Good luck with the project and let me know how it goes. Also if you want some pictures of the electronic cutout units the cars are using I can take some for you.

ruffy

Princeton
just got off the phone with my porsche specialists, he thinks there is room to implement this system where the heat exchangers sit. In a couple of days, we'll be doing the feasible studies and spatial testing. If this goes well, we'll go into production to make the worlds most dual personality exhaust system. Without doubt there'll be flames shooting out from below

I'd be most grateful to see any pics that you can provide, as it'll decrease my research and design time immensely. often, theres a fine line between what works and what you think works.

viperbob

SuperYellowfly,

It is preciesly at the heat exchanger point that I installed my mufflers. There is NO room before this point, and the sizes of the pipes are variable. I cut off my heat exchangers, installed a 12" dynomax billet stright through muffler and then out the Fabspeed muffler bypass tailpipe. Car picks up tremendous power with no cats (these were cat bypass pipes I started with) and this muffler setup.





If you have to go all the way to this point to install the bypass, then you will cut out the mufflers, and thats about it. You will still have the muffler weight in the car (70+ lbs), and the cats. You could accomplish the same thing if the track is your concern by just getting set fo muffler bypass tips from Fabspeed, taking off the donut clamp at the heat exchanger and removing the single bolt strap for the muffler. Now your car is lighter, it took 10-15 minutes, and your engine has the same power.

So other than kind of cool, what is the purpose you are trying to achieve??

ruffy

The idea was to route the exhaust directly out after the turbo such that the distance travelled is shorter. In essence, creating an alternative path with little or no resistance so to speak of. The idea is to use a solenoid to control this flow as an on off switch for the track and street use.

There is little doubt that liberating all forms of back flow will improve top end and spool up, the problem is whether there is space to create a secondary exit pipe to vent the alternative gases.

the idea stems from creating the shortest exhaust venting technically possible, yet retaining a full exhaust for the long journey home

viperbob

That is exactly why I built the above exhaust system. Factory look, great performance, louder than stock, but still fine for long journeys. I got rid of the weight, so it is also better for the track.

While the idea is sound, there is not much room to work with to perform what you are suggesting. Since you are already talking about the heat exchangers as the place to install the bypass, you have come all the way across the car to get to this point. This defeats some of your very sound design goals for exiting exhaust gases right after the turbos. I too like to think outside the box, so I 'The Lunatic' applaud your efforts. I'll think about this a little more and see if I can come up with any ideas.

My car is up in the air right now on jack stands (now there is a surprise) so I'll take some photos underneath the car of how this system works.

poorb0yw

Hi Bob,
Could you post those photos or send them to me? I love brainstorming about this stuff as well. Hopefully my next project will be enough to raise me to apprentice lunatic status .

How are the light housing air intakes coming along?

viperbob

Princeton,

I am spread a little too thin at the moment. Still trying to get the car back together from the broken wheel stud. While I have stuff apart, I decided to remove my PSS9s and add a locking collar to the bottom of the sway bar mount. When I put this back together I need to readjust the ride height in front by lowering 3/8s of an inch and then recorner balance. Then I bought a trailer yesterday, so added brakes to the second axle, and have to finishing install the weight distribution hitch.

Too many projects, not enough time.... Hopefully I can get everything together over this 3 day weekend. Well until my new tires come for the street and track wheels that I have to get mounted, or the tie downs for the 993 suspension, or the RS pulley, or.......

poorb0yw

Heheheh I know the feeling.

Oh yeah, I did end up going with that Tilton carbon/carbon clutch (but only twin disc instead of triple) mated to a RS weight flywheel. They insisted it was streetable and all the magazine reviews I've read say its nothing like the binary feeling of the multi disc metallic clutches.

Anyhow, I'll be sure to write up a review once I get it in and the Motec M48 all tuned up running the car well.

Q

superyellowfly
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cheers
Q