Is this the right forum? Is there any down side to placing an x-pipe or y-pipe close to manifolds/headers on a car? Does the turbulance cause problems if it's to close or can it cross/combine anywhere?

 

Um ... the y-pipe connects/bolts directly to the exhaust manifold. Headers replace the y-pipe with their own "equal length" piece. I am not exactly sure what you are asking.

 

I'm saying in exhaust design, is there a problem with putting the x/y-pipe crossover to close to the manifolds/headers. This isn't a question on the stock design, I'm talking theory. Basically, should it be a certain distance from the collector or does this not matter? I'm not sure if placing it to close to the collector would cause to much turbulance.

 

Yeah you confused the hell out of all of us I think since techniccally you shouldn't really be using the term y-pipe ther'

The closer to the headers the x-pipe is located the better, in theory anyways, the sooner the exhaust gasses equalize means the longer the distance of exhaust gasses flowing through the equalized section of pipe flowing smoother. However, due to space on the front-wheel drive I don't know if you have much of an option of where to put the x-pipe when converting to a true dual. Just my .02 cents, I'm sure someone is going to chime in and start comparing high/low end differences, lol.

 

Meximax has his Xpipe more or less where our stock cat goes, maybe a bit further ahead. Problem is tho, that the "y-pipe" he made- being unequal-lengthed, would make the purpose of an X-pipe (equalize pulses of pressure from both banks) useless, as one bank's pulses would arrive before the other. If a forward loop was done to the RH (firewall) bank (like in Cattman/ Hotshots) before it turned to the back (obviously taking measurements to verify they end up meeting at the Xpipe with equal pipe distance), then the X-pipe would indeed work.

Xpipes from what I know promote scavenging effect when they have equal length of piping meeting at the inlets, which is a good thing at any RPM, especially up top.

 

I think you got it correct there and from what I hear the shorter the crossover pipe the better as well......

 

Forgive the crudeness but I'm no artist. So would this design be a good one, or should I move the crossover down. As you can see it comes straight of the collectors and crosses over then goes straight down.


Shot at 2007-06-30

 

That design is good. It almost looks like it will bolt right up also Just get it equal length and make the crossover as short as possible or non-existent like in the pics, and as close to the collectors as possible. Now, end the talk and start the action

 

It should cross at 90 degrees, I'm waiting on some parts and having some problems with the muffler shop on design and cost. They wanted about 900 bucks for labor and pipes not including any resonators or tips. Seems kinda steep to me and all the piping was aluminized. I'm going to design it out of the stock y-pipe for collector placement and order SS pipes online I think. They also keep telling me to do compression bend but that seems kind of against the whole point of this project. Would I be better off going to a tuffy muffler or carX for this, the shop I went to is supposed to be the best in town but I don't get that impression.

 

Also, after the cross does is matter if it's equal length? There will be a slight difference due to the curve after X.

 

So if u were to do this design, what would be the ideal pipe size??? considering room under the chassis, etc....

 

If ground clearance is an issue here (which i doubt, there's plenty of space in the center channel to run two pipes side by side), but http://www.drgas.com/store/home.php --> oval piping.

 

Oval would actually be harder to fit, with round you can stick it up higher.

 

Yea I understand, should have been more specific. I looked into oval piping while me and streetzlegend were working on his rear mount turbo project, in which it was needed to run the intake tubing under the floorpan (and not next to the exhaust). So in THAT case as an example, in which ground clearance really was an issue, oval piping was strongly concidered.

But yes, to run them both in the center channel, normal round piping is the logical option.

 

Cool. But what size piping would be suitable for each bank of exhaust pipe, seeing that the cattman cat-back is 3" in diameter??

 

cattman catbacks are 2.5". I'd say 1.25-1.5"...

 

No way, that's to small. You have to remember that the area is much smaller if you halve the pipe. Here is a break down of pipe diameters and their area:

3.0 = 7.07
2.75 = 5.94
2.5 = 4.91
2.25 = 3.98
2.0 = 3.14

You also have to take into account the great flow of a 3" pipe versus a smaller pipe. You will have more turbulance going to a small pipe thus decreasing flow rate. The rule I have found is take the pipe area plus 20 percent for duals. So a 3" single at 7.07 would be equivalant to a 2.33 inch pipe or so. So you could go 2.25" and be good, but if your going to get into heavy mods down the road then a 2.5" dual would be the way to go. Also all your resonators/mufflers will be a 2.5" core and it's better to stay consistant.

 

^^ You sure?? 2.25 - 2.5 per bank of cylinders sounds like overkill. Considering built SR20's run 2.5" piping..

Jus for discussion sake

 

you DEFINITELY don't want to cross the pipes at 90 degrees. that would cause too much restriction in the pipe and cause more losses than gains. look for aftermarket merge collectors. Burns stainless makes the best of the best, but there are other companies out there that make quality ones as well.

 

All of the Magnaflow X-over Pipes I see here on Jegs...
http://www.jegs.com/webapp/wcs/store...59589_-1_11525

seem to intersect at what I estimate to be ~60*

 

That makes sense logically and that's the first conclusion I came up with. Precisely why I posted the question to figure it all out before welding begins.