Long Awaited Muffler test results...
KABOOM
08-12-2003 | 08:22 PM
#35
Addict
Rennlist Member
Rennlist
Site Sponsor
Rennlist Member
Rennlist
Site Sponsor
Joined: Oct 2002
Posts: 7,427
Likes: 85
From: san jose, california
Haha sorry Stephen
I was just having Kevin help me come to my senses... 
I'm pretty sure my car is what Porsche intended for Tiptronics when they were in the planning stage...
I was just having Kevin help me come to my senses... I'm pretty sure my car is what Porsche intended for Tiptronics when they were in the planning stage...
08-13-2003 | 07:15 AM
#39
Cruisin'
Joined: Jul 2002
Posts: 9
Likes: 0
From: England
Stephen sorry to trouble you, appreciate that I am from the UK & unlikely to
be able to put my business your way, but you can at least become an "INTERNATIONAL" authority on the subject of tuning 996TT, that's got to be good for business !!! I haven't seen a comparison test like this carried out in the UK, again may I say....................................
Congratulations Stephen on an excellent job, your test makes very interesting reading.
May I ask you a few quick questions.......................
1/ would the exhaust HP increases be much smaller on a standard car
2/ I noted that two of the best performers (Fabspeed) actually lost power & torque below 3500 revs. That means you only gain over the last 3000 revs & loose elswhere, how does this affect drivability ?
3/ I know this is a stupid question...but, one of my biggest reasons for me considering a sports exhaust is improved sound inside the car, it's too quiet as standard when you press on, although outside I find it sounds fine as standard . I can see the interior DB ratings 'but how can I understand exactly how much louder each Db is. I want a great sound when the pedal is to the metal, but not when I am on part throttle. Also ..presumably the interior DB would also be less on the move as the sound gets "left behind" ??
be able to put my business your way, but you can at least become an "INTERNATIONAL" authority on the subject of tuning 996TT, that's got to be good for business !!! I haven't seen a comparison test like this carried out in the UK, again may I say....................................
Congratulations Stephen on an excellent job, your test makes very interesting reading.
May I ask you a few quick questions.......................
1/ would the exhaust HP increases be much smaller on a standard car
2/ I noted that two of the best performers (Fabspeed) actually lost power & torque below 3500 revs. That means you only gain over the last 3000 revs & loose elswhere, how does this affect drivability ?
3/ I know this is a stupid question...but, one of my biggest reasons for me considering a sports exhaust is improved sound inside the car, it's too quiet as standard when you press on, although outside I find it sounds fine as standard . I can see the interior DB ratings 'but how can I understand exactly how much louder each Db is. I want a great sound when the pedal is to the metal, but not when I am on part throttle. Also ..presumably the interior DB would also be less on the move as the sound gets "left behind" ??
08-13-2003 | 12:42 PM
#40
Thread Starter
Rennlist Lifetime Member
Joined: Jun 2001
Posts: 4,574
Likes: 6
From: Kansas City
Certainly not any trouble at all. I am not sure I will ever be an authority on anything, except to my boys
From what I have seen I think some mufflers may provide better big type power delivery on the upper stages. Some did exactly as advertised and I have to assume were done on a stock car. Europipe for example shows their dyno sheets and back pressure. Their charts and our results show near the same outcome. I think their testing was done on a GTII or Stock car. Not sure, but the gains were the same even on my modified car. To pull a 40HP gain on a stock car is unrealistic. It is the difference to moving larger amounts of air faster than the stock system. At what threshold that stops I don't know. It is clear some systems respond better to bigger air movement than others.
Not really. The 996TT carries a CR of 9:4:1 with the adjusting cam timing and the 3mm valve lift at lower RPM ranges the deviance is small enough that the drivablity remains unchanged to the driver. Remember I am running bigger turbos and K16s will move faster. Although we know have a cure for that
Sound and noise levels is very person biased. For someone coming out of a stock muffler and directly to one of the louder mufflers you would have culture shock. If you are wanting something loud then it may not shock you. This was the hardest part to describe because the db level did not necessarily relate to resonance. Resonance is a frequency and the vibration and movement of air internal in the cab would start to relate to db, but as a whole this is hard to describe and record. The levels of resonance is different and acceptance is not the same by everyone. The way I judged over all resonance is the ability to carry a conversation with my boys in the back.
From what I have seen I think some mufflers may provide better big type power delivery on the upper stages. Some did exactly as advertised and I have to assume were done on a stock car. Europipe for example shows their dyno sheets and back pressure. Their charts and our results show near the same outcome. I think their testing was done on a GTII or Stock car. Not sure, but the gains were the same even on my modified car. To pull a 40HP gain on a stock car is unrealistic. It is the difference to moving larger amounts of air faster than the stock system. At what threshold that stops I don't know. It is clear some systems respond better to bigger air movement than others.
Not really. The 996TT carries a CR of 9:4:1 with the adjusting cam timing and the 3mm valve lift at lower RPM ranges the deviance is small enough that the drivablity remains unchanged to the driver. Remember I am running bigger turbos and K16s will move faster. Although we know have a cure for that
Sound and noise levels is very person biased. For someone coming out of a stock muffler and directly to one of the louder mufflers you would have culture shock. If you are wanting something loud then it may not shock you. This was the hardest part to describe because the db level did not necessarily relate to resonance. Resonance is a frequency and the vibration and movement of air internal in the cab would start to relate to db, but as a whole this is hard to describe and record. The levels of resonance is different and acceptance is not the same by everyone. The way I judged over all resonance is the ability to carry a conversation with my boys in the back.
08-14-2003 | 07:56 AM
#42
Cruisin'
Joined: Jul 2002
Posts: 9
Likes: 0
From: England
Stephen (& Dpblessing) many thanks for the reply. I have to say exhaust replacement isn't as easy as one first thinks.
The standard 996TT system (on a 2002 model) is just too quiet for driver "interaction", but I had a Cargraphic system fitted to a previous C2 & whilst this sounded fantastic at 5-7000rpm , the car sounded like a tractor on tickover or in the midrange. So I am cautious about replacing the stock system, I actually think the standard car sounds fine outside, both at tickover & WOT, but it is inside where it is too quiet.
The Fabspeed "quiet sport" looks like the best balanced system for me , BUT it is 8db louder outside at tickover (& has resonance in the midrange) when I first start my car in the morning it is loud as standard, so if what dpblessing says is right that is nearly twice as loud, sounds too much !!
Ho hum, the joys of making the right decision, any other input you guy's have on the subject are appreciated & thanks again Stephen for a great test, no doubt it will grow to include Cargraphic, Tubi & Techart in due course!!
The standard 996TT system (on a 2002 model) is just too quiet for driver "interaction", but I had a Cargraphic system fitted to a previous C2 & whilst this sounded fantastic at 5-7000rpm , the car sounded like a tractor on tickover or in the midrange. So I am cautious about replacing the stock system, I actually think the standard car sounds fine outside, both at tickover & WOT, but it is inside where it is too quiet.
The Fabspeed "quiet sport" looks like the best balanced system for me , BUT it is 8db louder outside at tickover (& has resonance in the midrange) when I first start my car in the morning it is loud as standard, so if what dpblessing says is right that is nearly twice as loud, sounds too much !!
Ho hum, the joys of making the right decision, any other input you guy's have on the subject are appreciated & thanks again Stephen for a great test, no doubt it will grow to include Cargraphic, Tubi & Techart in due course!!
08-14-2003 | 05:46 PM
#43
Rennlist Member
Joined: May 2001
Posts: 1,584
Likes: 71
From: Palo Alto and Carnelian Bay/Lk Tahoe
If the stock system sounds fine to you from outside, maybe it would be simpler to remove some sound deadening from the rear area first , if possible. After all, no matter which system you pick , power curve changes aside , what matters is how it sounds at the driver's seat - not to the stranger in the car trailing behind you. I wouldn't want 10-20 more HP if the majority of the time it sounds like I'm driving a booming resonating UPS delivery truck in daily stop and go driving or hiway cruise on an incline. That will sour the experience over time, no matter how thrilling the howl is at WOT the first few weeks .
08-14-2003 | 06:17 PM
#44
Thread Starter
Rennlist Lifetime Member
Joined: Jun 2001
Posts: 4,574
Likes: 6
From: Kansas City
For those that noticed the mirror on TQ and HP for the GHL I appreciate the heads up. The actual chart looks like this....The numbers in the 6K mark were 353 and the 6500 was 323.
