Craig & DDog - I totally agree with your feeling of surprise with the information Stef provided me. As with both of you, I am no expert either. AS Craig stated, there are 3 potential bottle necks: 1) Pipe diameter, 2) Cats, 3) Cans. Stef's data suggestes that with his 100 CEL cats (he is the only 1 using these particuliar cats at the moment), the size and engineering of the Cans, inconjunction with the tubing diameter out flows a 60mm straight pipe design. It's times like this that I wish I was a fluid dynamics expert. (Where is that Robert guy!). Tubing diameter must be more significant to flow rates than it's commonly given credit for. A.G. Bells's book suggests this and (my very limited) tubing diameter research was the primary reason I wanted this exhaust. Because it is a Europipe didn't hurt either.

 

All this is great, but a 5k 60lb exhaust? Why?

 

Are you suggesting that your exhaust weighs less? Perhaps 20 lbs?

Craig

 

well, I should know soon. maybe without the fancy tips it will weigh a little less.

But that wasn't my point. There are several good exhausts out there for the 996TT and none of them weigh 60lbs. My EP stage II weighs 55lbs! Cargraphic and Fabspeed weigh much less and put out as much if not more power. I guess I just don't get the EP hipe, but they do sound good if your into that.

 

zippy, pm sent.
carlos

 

Notwithstanding the aforementioned comments, and just for information purposes:

Cross sectional area of 84mm diameter pipe is just shy of 2x the cross sectional area of a 60mm pipe.

84mm pipe area = 5542 mm^2
60mm pipe area = 2827 mm^2

Hypothetically speaking, if the "new" 100 cell cats are physically larger than the "old" 100 cell cats, their respective "cell size" will be larger. Neglecting friction through the cats, it is conceivable that the cross sectional area sum of the cats is equivalent to the 5542 mm^2 area of the inlet piping.

Having pressurized exhaust gases expand upon exit to the atmosphere provides the best answer to the task of creating a free flowing exhaust system. This is the reason why short, straight, non-muffled, pipes are desirable for increased horsepower. However, if that same effect can be created by expanding those pressurized exhaust gases into an volume that simulates atmospheric pressure (the 2x area within the EP muffler), a similar benefit may be realized while also preserving some sound attenuation.

Just my $0.02.

 

garrett,
most people who drive Turbo (not GT2 ) don't take weight into consideration like u do. using the stock exhaust as a reference the EP is not heavier, and that's a plus when one's shopping.

 

i know i'm probably way oversimplifying this, but what do you mean specifically by cross sectional area? by increasing the stock piping less than 50 percent gives you double the cross sectional area? i'm not questioning you, i just don't understand. in my simple mind i would assume that you would have to double the size of the piping to get double cross sectional area.

 

area (of a circle) = pi * r^2

 

I gave up my spot last week to make way for a Porsche they had coming in. Must have been you. Oh well, I'm on vacation this week so no biggie. Can't wait to see the results on my grocery getter wagon.

 

Hey Dog, Ken is right. It is simple math.

Another way of looking at is if you took a 60 mm tube one foot long and a 84 mm tube one foot long and filled each tube with cocaine, the 84 mm tube would contain a little less than twice as much dope.

I believe 25.4 mm equals 1 inch.

 

I'm sure he is. Simple math for you guys. I haven't used math like that since high school. Most of my daily math consists of counting money and kilos. The only thing I could remember is that pi=3.14 and I have no clue what do with pi other than eat it

 

Correction - Stef e-mailed me to say the exhaust weighs 54 lbs.

 

Again, I am an uninformed, relatively simple-minded novice. However, I do not think you can create the effect of an atmospheric release within an exhaust pipe. Moving from 76 mm (the approximate diameter of a K24 exhaust outlet) to 84 mm for just a few inches (before the chamber muffler) will, IMHO, retain far more pressure/restriction than a release to the atmosphere. Moreover, after this relatively short 84 mm path, the exhaust gases enter the chamber muffler where they get reflected back and forth against angled walls within the chamber housing, thereby creating restriction and back pressure. Once again, this is far more pressurized and restrictive than a release to the atmosphere. Thereafter, the exhaust gases get released from the muffler through two different pipes, with diameters of 70 and 76 mm, as opposed to the 84 mm diameter than you analogized to an atmospheric release. I do not believe this exhaust path can be said to replicate a release to the atmosphere.

Additionally, while we are focused here on pipe diameter, pipe length is also relevant. With an "open pipe - no cat - stock tailpipeā€ exhaust (our reference point), the 60 mm pipe, albeit more restrictive than an 84 mm pipe, has a very short length in comparison to the EP Bazooka.

Craig

 

Stef said I could show a few pictures of the completed Exhaust:

http://www.evoms.com/members/Zippy/Default.asp