exhaust crossovers-h pipe or x pipe

[Guest needwaymorespeed]

Ive been thinking of making an x pipe out of two 90s cut and welded in the middle does anyone know what the angle are on the dr gas piece??

Has anyone run the flowmaster hewader collectors that go 4 into 2 into 1??

 

Im just wondering how well this stuff works or if its all hype.

thanks

Curtis

[pparaska]

The one I have from Dr. Gas looks like two press bent (I know they say they're mandrel but they look press bent to me) 90s. If you're making your own, lay out the exhaust first and make the angle greater than 90. It was difficult to turn out of the Dr. Gas piece and keep the pipes in the tunnel.

 

Just make sure that the divider created by the two pipe bends coming together is in the center, when looking at the inlet of each bend. This is so you get a good split of the exhaust pulse from each inlet.

 

If you can weld decently, this part shouldn't be hard to make. I was real surprised at the product, considering $90 for just the X-pipe union. I think you're better off making your own, especially under the Z in that tunnel.

 

BTW, I love the sound the X-pipe gives! No idea if I'd ever be able to tell the power/torque difference if any.

[Guest needwaymorespeed]

I saw those pieces when they first came out and thats what I thought also-looked like to 90s to me also.

I talked to Dr gas,when I got the price I thought id weld it up myself,Dr gas claims theres all this math involved with them,My response was" oh how funny you never asked my engine size or header tube length diameter, the length of head pipes or anything all you asked is what diameter of pipe did I want. seems to me if there was math involved you'd need all that info"

he didnt know what to say

Cool il make it then,how big do you think that hole is in the middle,the one I saw was already installed

thanks

Curtis

[pparaska]

Don't have my car - it's at the paint shop - or I'd measure it for you. I think the cross section on my 2.5" pipe version at the center was oblong, probably an ellipse with a 2.5" height and 3.5-4" width.

[Guest Anonymous]

Although I havn't seen them, I believe the 4-2-1 collector is similar in function to the old tri-Y header which have been around a long long time. It boost the lower end response somewhat I believe. I think the old Mustang cobra's had a similar exhaust available on the gt350r? Can't recall, but I know its helps low end just like a crossover, X pipe etc.

 

Lone

[Guest Tom Scala]

I run the Dr Gas 3" X-over on a low 12 sec big block equipped car and picked up nearly .2 tenths and 1MPH on average with no other changes. It increases low & mid range torque so if you have a traction problem now it will be worse after installing the X pipe.I've heard reports on very high HP cars(10 sec & quicker) that it will cost performance though. BTW mine is mandrel bent and 2 90 degree pieces.

[pparaska]

Tom, thanks for that data. Did you notice a difference in the sound of the exhuast? Was it smoother/more even?

 

I need to clarify my previous post. The pipe in the 90s of my 2.5" Dr. Gas X-pipe may not have been press bent, but it was certainly reduced from the 2.5" inlets/outlets. It looked like either the pipe was press bent, or a smaller pipe was used and then expanded at the ends. It was expanded to accept 2.5" exhaust tubing though.

[Guest Tom Scala]

The exhaust tone did really change witht the X-pipe. Definetly smoother and quieter under load. At 1/2 to full throttle with 3.0" Dynomax Super Turbos it is earily quiet. Part throttle cruise still has the usual drone at 1800-2200 RPM though,and at idle it may even be slightly louder. My 3" x-pipe has expanded ends that a 3" OD pipe fit into. I wonder why they didn't make the 2.5" that way? As a side note my best 60' times before the X-pipe were in the 1.7 range. Now with good traction (harder to get) I routinely run mid to high 1.6's. I was thinking that with the extra low end I have now I could go with more cam duration to get higher mid range/top end numbers and still have good low end torque,or get rid of my 3000 stall convertor and run something a little tighter to get more MPH and more consistant traction.

[Guest needwaymorespeed]

well I just cut into two stainless steel 2.5 inch 90s,this should be nice! Where the two 90's meet at the top and the bottom is curved

so when you look into the x you have a raised center section about .125 of an inch top and bottom,is this too much, are the stock pieces flat in this area??

Thanks

Curtis

[pparaska]

If what you're asking is what the Dr. Gas pieces look like there, this is what I remember:

 

The outside of the 90s had a cut out that did not extend to the full diameter of the pipe, maybe 7/8 of the diameter. The two elbows were butted together to align these cut-outs and welded from the outside all around. Then a flat sheet was welded to the top and bottom of the X to help hold it together.

 

The nice thing was that when you looked straight through the inlet (it was marked inlet and outlet with arrows) you could see the divider created by the joining of the two 90s right in the center of the flow path. That's something I'd shoot for.

[Guest needwaymorespeed]

Pete thanks

so looking down, the divider is raised about a 1/4 in or so on the floor and roof of part?

 

could you see what the difference was on front to back?? The arrows?

 

thanks alot

Curtis

[pparaska]

Yes, that 1/4 sounds about right. You should have a larger cross section at the center of the X.

 

As for what was different in vs out, I think the divider was better centered if I looked in the "in" side - they probably just make them and then look and decide which end has the divider centered better .