JLHendrix

I am close to doing my first and only mod to my 2011 C2. Need a little more engine growl and have decided to go with simple bypass of primary (center) muffler (either sharkwerks or fabspeed simple cross pipe only) I am aware of the debate over dyno readings with AWE and others. My question is for those of you who have some version of the primary muffler bypass. Do you feel any loss in low and midrange torque? Since I do not track my car but enjoy spirited driving, I am not really concerned about making more horsepower at 6500 just want to keep the thrill at 3500 to 5000rpm. thanks John

gota911

I can't answer your question from personal experience (yet) but the Sharkwerks site states there is a 12 HP and 14 torque gain with their by-pass pipes.

Sharkwerks By-Pass

When I get my 997.2, the Sharkwerks by-pass pipes will be my first mod.

kosmo

well, i divern one w/ a full tubi set up. This set up also deletes the center muffler. I thought it was slighty more powerful. Sound was great .

John@Fabspeed

Hey Hendrix, I attached our Dyno result showing the X Pipe on a 997.2 which made significant HP and TQ increase. We like to have the exhaust banks from the drivers and passenger side talk to each other for power increase, exhaust flow balancing and sound enhancement. Most race cars are doing X Pipes to increase power and keep the sound down. The X also creates a little more back-pressure which is what the engine needs on certain applications.

Dyno: http://www.fabspeed.com/dyno1.html

Datura

I made the mistake of installing the Fabspeed Muffler Bypass Pipes on my '06 Carrera S and it was so obnoxiously loud that I had the stock mufflers re-installed soon after. If you spend anytime at all in traffic doing starts and stops you will be hated by the masses, and don't even begin to think that your significant other will be going anywhere with you in the Porsche. Do you have teenagers in your neighbors hood who have removed their mufflers to sound cool to the chicks?? Same deal.

IMO I would look for some sort of lower restriction mufflers for the added noise you want, especially since you say you don't track much.

Skibum

I think he's referring to the center bypass, and not the dumps that Fabspeed offers to eliminate the side cans.

okbarnett

you should read the results on sharkwerks and evoms web site, they did the dyno test.

https://rennlist.com/forums/997-foru...dk-tuning.html

JLHendrix

Thanks guys. I am looking at replacing the 997.2 center muffler only. I am leaning toward the Sharkwerks crossover design because there is too much controversy over the effectiveness of open/merger designs and whether add or diminish HP. The only concern I have is that in some cases (like all of my motorcyles) a less restrictive exhaust will provide higher gains only in the high RPM ranges and alters the power band in a way that gives you less torque on tap earlier in the band. I have looked at all the dyno results that are published but this only begs the question of whether dyno testing is reliable and under what parameters. So for you guys who have used only the simple bypass solution to the anemic exhaust note problem, does it pull as hard as it used to before you replaced the center muffler?

gota911

JL,

Contact Alex at Sharkwerks and express your concern about loss of low end torque. I'll believe he can and will put your concerns to rest.

964RS_NGT

Actually, the well respected Akrapovic companty states that their 997.2 titanium system adds midrange power when combined with their X-type centre muffler replacement. Without it, there is barely a difference worth mentioning.
Dyno graph's are avaliable at their website;
http://www.akrapovic.com/car-exhaust...on-8451983739/
http://www.akrapovic.com/car-exhaust...on-410fa2fbd6/

f4 plt

I have had the Sharkwerks center by pass on my '09 C2S for over 2 years (23,000 miles) and still like it. What not to like, It reduces 10 lbs at the very rear, adds some Hp, great sound and outstanding build. I do not feel any loss of torque and while not dyno'd can feel some increased low end power. I think mine was the first production unit and the installation was easy and I did it with the car on the ground.

Absolutely no drone in the cockpit at any speed. Quiet at highway speed but add some throttle and the engine come alive.

JLHendrix

F4, that settles it for me. Thanks.

seapar

Having Sharkwerks bypass installed tomorrow on 2009 c4S pdk. Will post feedback. Talk to Alex for ? Arrived UPS in two days. Wife knows something's up but she drives a 05 manual Boxster which sounds great esp with top down.

Dan@SharkWerks

Hi John, I'll try to help with a couple of these questions, thanks to those who have already helped

I'm not an expert on motorcycle exhausts, but these bikes -- I am guessing they are pretty well tuned from the factory and have pretty low peak torque to begin with compared to peak horsepower, because the power is in the higher RPM range. Also on these bikes, do they have headers or catalytic converters as restrictive as a Porsche?

The reason I ask is that the Porsche exhaust is pretty restrictive compared to most free flowing race exhausts (and I imagine motorcycle exhausts), so removing one center muffler isn't quite as drastic in terms of changing backpressure as removing it from another vehicle. The Porsche still has 2 OEM side mufflers, OEM cats and headers at that point.

If you were to remove both side mufflers, install headers and freer flowing cats, I imagine you could see a loss in torque in the lower RPMs, and maybe the 3.8L revs high enough to pickup power at the higher RPM range -- but I haven't tested it.

Our dyno (which I do trust wholly, I'll explain why below) shows no loss in torque and only gains in HP and torque at all applicable RPMs:



Dynos can never tell the whole story (it's not real driving afterall) but it's the industry standard. I prefer many-many 1/4 mile and 1-mile acceleration tests but sometimes it's not as easy without a dragstrip nearby. The reason I trust our dyno graph is because we took our car to Stasis Engineering, an Audi tuner that used to be in our area. They had the only AWD mechanically linked Mustang dyno in our region, and I think this is the most effective way to dyno a Porsche (even on a 2WD 997, there will be inaccurate numbers / problems if the front wheels are not spinning as fast as the rear).

We have no working relationship with Stasis and as a regular customer I don't think they would skew our results.

The process for dynoing these cars is something that really makes all the difference. I believe the only effective way to dyno a car with a part like this is to strap it in and make as many baseline pulls as it takes to establish a repeatable number. This might take 10 dyno pulls, but eventually you'll have some number, 330 WHP etc. again and again. Or it starts to drop off slightly from heatsoak, so you can stop and pull your repeatable peak #.

Then you swap out the part and again strap it in to measure the delta. Again it takes many pulls for the ECU to adapt and the final power to be measured. On our PDK car we probably did about 20-30 dyno pulls just for the exhaust measurement. Finally the same pattern will emerge; the ECU will have done all it can and the peak power will stop climbing up, the final numbers are noted.

For ECU tuning we probably did another 100+ dyno pulls. For our 996 and 997 GT3 3.9L cars, we've dynoed them hundreds of times, I know Todd@EVOMS has dynoed his 997 Turbo thousands of times (I think 2500+ was their record last time I asked )

seapar

Had the Sharkwerks bypass installed this morning. My early review is that " I like it". Controlled with your right foot and normal vs sport vs manual mode and your tachometer. DE coming up 9/3 and I am looking forward to it for sure. First one on PSS tires too.