Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Incredible Exhaust System (repost)

Ratchie, I agree with your point, but your general concept is wrong.

Two 2.25 pipes with "ugly" crush bends (effective diameter of 2 inches) will flow as much as a 2.8 inch pipe. Which is plenty for all but the most extreme blown SVTs. (Remember the infamous 3.0inch SMA system? It actually lost power over a well designed 2.5 inch system....) But its not the equivalent of a 4 inch pipe. In fact, cross sectionnal area of 2 2inch pipes is half of that of a single 4 inch pipe! But then, everyone will agree that a 4inch pipe is overkill on pretty much all svts....or street cars for that matter...

So my point (yes its coming) is that the mandrel bends would be important on the cat to muffler length on a cardoc system (to keep the inner diameter a nice even 2.5 inches), but the advantage is negligeable after that.

Bnoon, true, I left out a bunch, but I was trying to keep it short. Not only just that it is a pulse, but that the pulse's duration and frequency changes with RPM. So a system can be tuned to a cetain RPM but not all RPM's Also temperature changes (Gas laws PV1=PV2, etc). Fortunately we are 4 cycle and not 2 cycle, where the scavenging effects, reflection of pulses, etc are much more important and add to the complexity of the exhaust design.

I guess the word here is that exhausts are more then a length of pipe to keep the exhaust quiet and behind the car .

I 100% agree Mangler, does your Cardoc system have a crush bend in the front pipe before the muffler? Mine has a slight bend, but not a crush bend (Looks to be some type of alignment bend for the muffler) but there is not any type of crush there.

Anyhow - You are correct - The system should be able support a 2.5L and 3.0L and upwards

John

Dual 2.0" pipes are not the same as 4.0". You can't just add the diameters. a 2.0" pipe has a cross-sectional area of 3.14sq.in. (Pi(r)^2). Dual 2.0 inch pipes have a cross sectional area of 6.28 sq.in., which is the same as a single 2.828" pipe.

Rough generalization - But it gets the point across. You are about right.

John

Another point you are missing is the fact it "is" a quasi-dual exhaust regardless where the Y-split is.

You keep comparing the 2x 2.25" crush bent pipes to a single 2.5" pipe (or stock 2.25") which is incorrect.

His exhaust has a 2.25" stock pipe running to a muffler that splits it into 2 crush bent 2.25" pipes.
2.25" crush bent piping has an effective size around 1.88" at the 90 degree bends.

This would in effect make it smaller in flow area than the stock SVT exhaust which has 2" mandrel bent duals. Also it has the drawbacks stated previously of slowing down the air flow & causing added turbulence by repeatedly decreasing & expanding the pipe size.

Christ have Mercy! I am so fekking sick and tired of this bullshizzle. Will someone please slap down som dyno plots and put this to an end?

Until then:

SHUT YOUR PIE HOLES

No argument, no matter how foolproof can stifle a dyno plot. NONE!. So until the time arises that we see a real live dyno plot, we will all keep arguing over this piddly shiit....

While I'm not an airflow expert, well schooled in physics, or deeply religious (in the trditional sense of the word at least - recall Grace in the F&F, that I can handle), AMEN TO WHAT OUR REPTILIAN FRIEND FROM FLORIDA SAID!

I've been following this thread for a few days now. Let me first just say that anyone that has read to this point can undestand why i choose to buy a catback instead of design my own.

Crush vs Mandrel. Hmmm, lets see.... It seems to me that most of the larger exhaust manufactures use mandrel bends. Do you really think they would do so if there was not a benefit? They could charge the same price for crush bent systems as mandrel bent, and i think we can all agree that crush bent costs less to manufacture. Not to say that there is even a measurable difference in a single bend but my factory SE system had no less than 8 in the catback section. My borla has none.

I am an MET, though im a computer geek by trade. Any ME out there should agree that there are a number of vaiables that have to be considered in designing an exhaust system, and though most have been mentioned, they have not been mentioned together and in the proper context. This isn't just back yard science guys. I don't claim to have all the answeres or know all the equations.

As far as cardocs system goes, the original post just looked like spam to me, and i think that may be part of the reason so many people started slinging. That said, It would be nice to see a head to head dyno and scale shootout between all the manufactures (borla, brullen, cardoc, etc etc) various configurations.

Whats my point? I forgot it after reading through all this crap.

For all of you SVTs with aftermarket pipes:

What did you do with the old ones???

I just want to upgrade a little bit from the tiny Zetec stock pipes to what you guys were born with.

Let me know if there are any out there for cheap.