Gutting a cat... with pics!
06-19-2012, 01:24 PM
#32
993Cup unmuffled
2007RSR
2008RSR
2009 Cup unmuffled
2009 RSR
SC/RS
964RS/lw
06-19-2012, 03:00 PM
#33
Rennlist Member
There are different ways to configure the exhaust
here is 1&2, 3&4 pairing
here 1&3, 2&4 pairing
here a 1&4, 2&3
Which you use depends on firing order and hoe you want to affect the torque curve
non sequential tri-y has the widest torque spread, 4 into 1 the narrowest but also the most peak hp, non sequential tri-y is in the middle
When I raced Honda MC we played around w/ this a lot, I see that current 4 cyl inline superbikes are also playing w/ crank variations to further alter the torque curves
here is 1&2, 3&4 pairing
here 1&3, 2&4 pairing
here a 1&4, 2&3
Which you use depends on firing order and hoe you want to affect the torque curve
non sequential tri-y has the widest torque spread, 4 into 1 the narrowest but also the most peak hp, non sequential tri-y is in the middle
When I raced Honda MC we played around w/ this a lot, I see that current 4 cyl inline superbikes are also playing w/ crank variations to further alter the torque curves
Any dyno results for the *** setup?
06-19-2012, 03:35 PM
#34
1-3 paired , 4-2 paired gives B--B--S--S to each primary pair, I added the extra - because the cyl fire every 180* instead of the 90* in a V8
so this one
06-19-2012, 03:43 PM
#35
Rennlist Member
06-22-2012, 12:20 PM
#36
Rennlist Member
I visited the manufacturer of Dansk Mufflers for our cars.
They are located in Viborg, Denmark and are called JP Group a/s.
The company makes mufflers, headers, catalytic converters, etc. for Porsche to a very high standard in stainless steel.
I found the company to be much larger than I expected with a 270,000 square foot facility that not only makes exhaust for Porsche but other makes as well.
They also are a distributing manufacturer for many other chassis parts and body panels.
The owner appears to be a Porsche freak and has a showroom with his collection of cars, mostly Porsche's, which I visited along with the manufacturing facility.
He drives a 991 Convertible and a Panamera.
The front door of JP Group a/s
Inside in a high security area is the entrance to their "showroom" with various cars collected and a show area for all the other parts that JP makes
for suspension, lighting, etc. besides just exhaust which are shown in the glass cases in the background.
A familiar shape done in fiberglass is over the door to the showroom
Inside is an immaculate collection that includes many Porsche's plus things like the 10th from last VW Beatle ever made which has only 700 km on the odometer.
[IMG]
[/IMG]
This is the Dansk 993 header system with 100 cell Cats and mufflers.
The pipes to the right are Bischoff 993 Cat bypass pipes, in the center is a 964 primary muffler bypass.
Examples of early 911 Dansk mufflers both in stock and "Motorsport" versions
993 Bischoff OE heat exchanger pipes in process of fabrication.
Stainless covers for early 911 heat exchanger.
They are located in Viborg, Denmark and are called JP Group a/s.
The company makes mufflers, headers, catalytic converters, etc. for Porsche to a very high standard in stainless steel.
I found the company to be much larger than I expected with a 270,000 square foot facility that not only makes exhaust for Porsche but other makes as well.
They also are a distributing manufacturer for many other chassis parts and body panels.
The owner appears to be a Porsche freak and has a showroom with his collection of cars, mostly Porsche's, which I visited along with the manufacturing facility.
He drives a 991 Convertible and a Panamera.
The front door of JP Group a/s
Inside in a high security area is the entrance to their "showroom" with various cars collected and a show area for all the other parts that JP makes
for suspension, lighting, etc. besides just exhaust which are shown in the glass cases in the background.
A familiar shape done in fiberglass is over the door to the showroom
Inside is an immaculate collection that includes many Porsche's plus things like the 10th from last VW Beatle ever made which has only 700 km on the odometer.
[IMG]
[/IMG]This is the Dansk 993 header system with 100 cell Cats and mufflers.
The pipes to the right are Bischoff 993 Cat bypass pipes, in the center is a 964 primary muffler bypass.
Examples of early 911 Dansk mufflers both in stock and "Motorsport" versions
993 Bischoff OE heat exchanger pipes in process of fabrication.
Stainless covers for early 911 heat exchanger.
07-16-2012, 09:17 AM
#38
Rennlist Member
So to conclude (and correct me if I am wrong)
1. A true X pipe has not been proven to make btter sound, HP or Torque.
2. Cat bypass will lower torque a bit but is louder.
3. Nobody currently makes a "u bend" cat bypass that follows the route of the stock airflow and retains most the backpressure/torque without the use of any cats but still has the bungs for O2 sensors.
4. If someone were to develop such a thing, there maight be interet from others in buying such a thing as long as it is bolt on with no welding, stainless and affordable...say under $500.
1. A true X pipe has not been proven to make btter sound, HP or Torque.
2. Cat bypass will lower torque a bit but is louder.
3. Nobody currently makes a "u bend" cat bypass that follows the route of the stock airflow and retains most the backpressure/torque without the use of any cats but still has the bungs for O2 sensors.
4. If someone were to develop such a thing, there maight be interet from others in buying such a thing as long as it is bolt on with no welding, stainless and affordable...say under $500.
