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Good morning Rennlisters,
this is my first thread so I think I must also present myself:
I am an italian Porsche 993 addicted: entusiast of my '96 row italian NB polar silver carrera coupé, I am trying to take care of her as much as I can.
It handles of a Varioram 3.6 - 210 kW engine with stock exhaust, except a 2x200 inserts inside the Bischoff Cat Box (it is the one with only one lambda O2 sensor - OBDI) and last year I changed the original ECU with the Steve **** Chip.
Now, honestly, I am quite happy about my 993, but looking around for weight reduction I found informations regarding a possible (and small) increase in hp and torque changing the mufflers and the exhaust headers.
I am not interested in a louder sound and not even in changing the 200 cells cat box (Bischoff) I have, that's why I am not interested in an entire exhaust set, but only for specific parts change, which in my case I'm considering would be Mufflers and Headers.
The sound is already very nice and civilised, that's why I could accept only a very small increase in loudness: I hope in some of your sincere advice.
We have an expression: "You can't have your cake and eat it too." IMHO, you are trying to obtain two things which are at the opposite ends of the spectrum. Trying to reduce weight in the exhaust system without getting louder is an oxymoron.
Trying to reduce weight in the exhaust system without getting louder is an oxymoron.
Yes, but there can be a balance.
I currently have the Fabspeed 200 cell X-pipe with Max Flow Mufflers. Fabspeed claims the mufflers are 15 pounds later than OEM. I do not find the combination that loud, at WOT you can still mainly hear the flat 6/varioram working away.
Previously I had Fister stage III with stock exhaust/cells. At WOT you are not hearing much if any of the flat 6/varioram, besides which the neighbors could hear me coming a half mile away.
Fabspeed claims HP/torque gains which the rear is telling me are real.
As to headers, do you want to have the heat exchange boxes? This will limit your choices.
There could be, " a possible (and small) increase in hp and torque changing the mufflers and the exhaust headers."
I think we all will admit that a good portion of the HP of the 993 over the 964 goes back to engineering the 993 with a less restrictive exhaust system. So the point being, PAG engineered the 993 exhaust system for optimum performance and emissions compliance....and we are to believe that aftermarket manufacturers know the 993 exhaust better than PAG? I think not.
My 87,000 mile 993, bone stock, dynos at 257 HP to with stock 993 mufflers and a stock cat. Back in the day, before I reverted to stock to keep the noise down, allowing me to run tracks with a 90 dB limit, I had all the trick 993 exhaust stuff on the car, cost lots of money, and it caused me to fail my
bi-annual emissions test with a Check Engine Light aka CEL. But, The car dyno'd at 267, 10 HP difference. Was it worth it? Well I don't have this trick stuff anymore, and I am not looking to acquire any such products.
Some postulate that a 100 Lb weight reduction is good for 8 - 10 HP...that's the way to go, or is it? Here is list of things that a friend removed from his car and the weight savings ge experienced:
Removed the sun top 45 pounds. More details, he had the sun top roof cut off and replaced with a sun top delete roof he sourced from Germany,
Removed the power steering 18 pounds You ever try parking with 245/35/18 front tires? Chore at best.
Removed Cruise Control 4 pounds, ho hum, don't use it anyway. I use cruise control on my Prius, not the 993.
Removed air conditioning 35 pounds (Actually, he removed the heat and kept the air conditioning.) We live in sunny CA, and it get's very sunny in the summer. This mod is not for me...I like my heat AND my cold.
Remove the power windows 3 pounds.
Installed thin glass 18 pounds.
I am only posting these notes so you don't "reinvent the wheel", and be careful what you wish for. Ever mod has an upside, and unfortunately, a downside.
Good morning,
the time zone plays an important role, and it was nice to open the page and find your answers.
"You can't have your cake and eat it too." IMHO, you are trying to obtain two things which are at the opposite ends of the spectrum. Trying to reduce weight in the exhaust system without getting louder is an oxymoron.
From what I read so far it seems that Silencers/Mufflers are the main system used by manufacturers to reduce the noise and eventually tune up the sound: the exhaust itself plays a role as well, but not as much as mufflers in noise reduction.
Also changing headers shape, thickness, material of course will change the sound stamp a bit or very much, but with stock mufflers I am quite sure the overall noise would be quite the same.
The sound now is nice and civilised, that's why I could accept only a small increase in loudness: my first question is if installing new 3 in 1 same length headers and mufflers there is a perceptible improvement in driving quality (throttle response, sharpness) and power curve, even without remapping again the ECU?
I mean if the Steve **** Chip must be changed with another one or if it self-adapts to the hardware changes.
Looking around I found many manufacturers (Cargraphic - Supersprint - Brombacher - X-Ost) but I focused my attenction on Fabspeed, i.e. Fabspeed Headers (and eventually Mufflers): all the producers above seem to have excellent reputation and experience, but Fabspeed seems to be the only one to produce Primary Headers with Bischoff flange and at the same time interchangeble with the OEM headers. (I mean, I can install the new headers at the place of the stock ones without any other change).
As to headers, do you want to have the heat exchange boxes? This will limit your choices.
BTW what 200 cell cats do you have?
Pirata I have installed in the original Bischoff Cat Box 2 Brain Technology EURO 2 200 CPSI cat: after that, I really noticed a nice improvement in torque and progression at high revs.
I am looking for efficient headers, without exchange box, with Bischoff flange, exchangeble with the original and new muffler, if also a better muffler flow would help.
I use my 993 for road use and max. 5 trackday/year (not in an heavy way, not endurance, 2-3 laps and then cooling laps) , that's why I wouldn't like torque loss at low and mid range: what I search is an optimization of the torque curve along the entire arc of motor use, and consequentially a bit more torque at low&mid range and a bit more hp at high revs.
If this comes together with some weight reduction, with just a small noise increase, is perfect.
I drove the car without mufflers, and the result was bad in many ways: really too loud (Headache in 5 minutes), bad resoncances between 2500 and 3000 rpm and simultaneously torque loss at low and mid rpm, very strong soundwave vibrations entering the cockpit.
The only good part is above 5000rpm: from that point on the sound is really race car style but becomes lighter while revving and probably it has an improvement in quickness.
If without mufflers there is such a loss in torque under 5000 rpm, this means that the back pressure or the length of the exhaust channel has an influence even downstream the Cat Box.
Fabspeed, Cargraphic, etc. advertise a 5 to 10 hp gain with a muffler change.
The question is: this gain at 6200 rpm comes with a loss in torque below 5000rpm?
I took also info regarding the inner diameter of the OEM primary header which is 39mm exactly as the cilinder head outlet diamter: so I am asking myself, if it is so important not to reduce the speed of the gas, especially not in a sudden, to prevent gas to expand and loose energy (temperature decrease and speed slow down), why most of the producers of 3 in 1 same length header use a 42mm inner diameter instead of 39mm?
Thinking about the ideal length of the primary headers - ideal in the way it fits my needs best - probably the ideal length would be the one of the middle cylinder of the OEM headers: I didn't measure their lengths yet but it is reasonable that Porsche, not to deviate too much from the ideal length value, have made a shorter duct and a longer than the central one to reduce the length difference, which in the fact should represent the average length of the three primary ducts.
Valve diameter is 50mm, valve seat should be approx. a bit more than 49mm: so the the diameter at first is 49mm, then in the cylinder head outlet becomes 39mm and then again 39mm in the stock primary header? Is this right? Probably they design it like that to accelerate the gas flow, but if this is right, probably it is not a good idea to increase the diameter installing a 42mm inner diameter primary header.
There must be a reason for that: maybe they produce wider primary header like that to have an hp gain at high revs and increasing the primary length at the same time they have found a way not to loose torque.
So far, without any feedback about it, I am considering Fabspeed Primary Header (which has Bischoff flange, but I still don't know the specs of their Headers) together with Fabspeed Muffler or Fister Stage II as suggested by Ed Hughes.
P.
Last edited by nothingbutgt3; 05-04-2017 at 09:19 AM.
Reason: writing mistakes
I don't want to be a "buzz kill": It's your car, do with it what you desire. Since 2001, I have been doing mods to my car, a very exhilarating and addictive process, love the high of a new mod, we all do! I am still doing little tweaks, with a big one coming some day, an engine rebuild. Ideally to 993 RS specs, but then I have emissions to deal with...don't think a RS spec engine will pass...and my wallet...it would be severely hammered with a RS motor, at least $25,000. Clearly I don't have a "day job", or I would put up these long rambling posts...it's sort of a hobby, so bear with me.
Keep in mind, a "butt dyno", a roll down the window and listen to the exhilarating exhaust note "dyno", is not the same as the real deal. You need dyno results. If you are looking for HP mods, I would suggest that performance increases/decreases need to be confirmed by a reliable dyno. Exhaust, from the intake, through the tailpipe is a system. As mentioned above, the PAG OEM exhaust system, back to the cats and the mufflers is engineered for optimum performance and minimal compromise coupled with emissions efficiencies.
Agreed, the 993 OEM cat does add weight to the back end, some 30 Lbs (I weighed mine...my scale says 30 Lbs). I tried 200 cell cats, a X pipe, ramped up the exhaust noise through my Fabspeed Maxflows. The down side, can't pass CA emissions on a predictable basis, barely passed once, flunked the second time. My conclusion, PAG designed a highly functional cat, with what is in essence a built in X pipe, linked to an engine that puts out, in my case with stock exhaust, 257 HP to the rear wheels, down a mere 9% from the advertised HP of 282, that's pretty good. So I re-installed the factory cat and stock mufflers, passed emissions with flying colors and can pass a 90 dB sound check for my annual trek to Laguna Seca Raceway in Monterey, CA.
Mufflers: To paraphrase Darin Fister (FD Motorsports) Stock muffs are around 17 lbs each and Stage IIIs are about 10lbs each, so you lose about 14 lbs off the *** end." Here is what you gain, very mellow sound with Stage II, a bit more raucous sound with Stage III. I'd have these muffs but for my 90 dB annual sound check at Laguna Seca. I have had 3 or more sets of FD Motorsports mufflers, loved them all...but went to Maxflow when I had the Fabspeed 200 cell cats and X pipe...I wanted a complete system. That phase passed when the inconvenience of changing back to stock every year for Laguna, and 2X every other year to pass CA emissions. I just rolled over and went back to Stock cat and exhaust. I took the mini-hit for the increased weight on the rear end. True, the car doesn't sound very exotic, but it works for me.
If I didn't have emissions and sound to concern myself with, would I put on a modified exhaust system, from headers, to X pipe to cat bypass (or 200 cell) and trick mufflers? To make this decision I look to Return on Investment (ROI), $$$ VS HP gain, and weight reduction. When I had all these items with the exception of headers (Cut your heater boxes apart, and voila, headers!), I gained 10 HP...I have multiple dynos off the same dyno to corroborate my story.
I suppose if I were breaking track records, or were about 1 second off the pace, and my AiM data suggested that I was driving the car to its potential (Not mine), and a small increase in HP and the loss of about 30 Lbs or so off the *** end, would put me over the top, I'd do it. But right now, that is not the case. In addition I run in a NASA weight to HP class, my HP is ideal at this point in time, 257 off off a 87,XXX engine! Thanks PAG gods for making such a fine product.
And thank the gods this post has come to a conclusion. I actually have to get to some chores now.
Thank you for your exhaustive (talking about exhaust solutions) answer Martin!
So silencers can be useful only for those who are looking for a more eye-catching sound or a slight weight reduction but do not lead to any improvement in engine performance.
What about the primary headers?
Frankly speaking, I don't have an RSR, don't plan to build one, but why RSR had 3 into 1 header if the original headers were perfect born?
The 3 primary ducts have a quite big length difference and if this was the way to achieve the best performance in the flat 6 engine, why did PAG change the system into a 3 - 1 for the RSR?
Wasn't RSR their AC Flat 6 last swan song? So they put a bad working 3 - 1 header system into their quickest race car?
Maybe I am wrong, but what I think is that the stock header is good enough, especially considering a very well designed exhaust system, but it is not the best possible primary header system.
Then changing the stock header exhaust with another 3 - 1 designed not as well as it should be could surely lead to Unsatisfactory results or even malfunctions - that's for sure.
Fister II mufflers, gain a little sound and lose a lot of weight.
+ 993 The stock mufflers weigh about 17 lbs each I believe. The Fister II's run about 12 lbs., and are quite civilized. They sound perfect IMHO when mated to the Fabspeed Sport Cats with the 200 cell.
From the documentation I could acquire, Changes to the mufflers have no influence on the engine's delivery curve, but only on the exhaust sound.
3 into 1 manifolds would have some kind of improvement, but only if really well engineered and manufactured
the thing that really has a noticable impact on the power and torque delivery is the exchange of the 500 or 400 cells cats into 200 cells cats, that I have already installed on my car inside the original box.
I asked infors writing emails to many manufacturers or sellers, such as Fabspeed, Cargraphic, Friedrich, Supersprint, FVD, Carnewal, but I have to say that so far only Gert Carnewal and Cargraphic answered me, showing attention to its customers.
What surprises me is the lack of attention to models such as SC, 3.2, 964 and 993, that are more and more becoming cars for very seldom use: in my opinion it is not rare the owner could be interested in a very specific and targeted improvement for a better, more enjoyable driving experience, the few times he drives his "jewel".
Probably someone who purchases a brand new 991, which has everything in it (and even more), has less interest to discover how to personalise his car.
Hi Rennlisters,
I want to update you about the evolution of this topic.
After having asked for informations here and having got very good advices, after cunsulting per email the most important exhaust manifold manufacturers and having recieved, each with its own time, responses more or less useful, I came to a summary and took the decision of buying the collectors of Stainless steel manufactured by Friedrich-Motorsport (Germany), which in addition to seemingly great workmanship, are the only ones with Bischoff flanges that can be simply installed in place of the original manifolds without the need for additional accessories.
Friedrich-Motorsport customer service has paid attention to my requests and I have been given the specifications of their product.
Once I have installed and tested them in a road test, I will be able to tell you detailed informations, i.e. my personal impressions concerning the expected performance improvements.
You do know that you are going to lose your heater?
Yes, I considered this: I basically use the car from April until the end of November, and where I live (Tuscany - Italy), during these months - especially in the summer - I use Air Conditioning, but not the heating system.
When I lived in San Diego, even during summer, some times on cool morning drives in the east county mountains, defroster was mandatory. That's part of heating...
05-03-2017, 01:50 PM
Row Porsche 993 Exhaust Change advices
I have installed in the original Bischoff Cat Box 2 Brain Technology EURO 2 200 CPSI cat: after that, I really noticed a nice improvement in torque and progression at high revs.
