4 inch to twin 3 inch collector

[CRAVED]

Gday,

 

I have been thinking about changing my exhaust system on my skyline. The current system is a 3 inch dump pipe of a HKS 3040 going down to Cat convertor (now believed melted) through straight pipe to a X-Force 3" inlet and twin 2.5" outlets.

 

I have decided for extra flow and reduced noise to go to a 4" off the turbo to a 4" inlet Cat convertor then split the 4" outlet into twin 3" exhaust pipes back to a pair of rear mufflers.

 

 

Now i'd like to make this up myself if possible so i am after ideas and pictures of a collecter design that will merge the 3 pipes together smoothly for flow.

 

 

any help would be great.

[CRAVED]

Well looks like the best option is to squash some 4" pipe down into an oval shape on one end then try to splice in 2 3" pipes into the end of it.

 

will try it out, but would be good if anyone has done something similar

[TimZ]

Well looks like the best option is to squash some 4" pipe down into an oval shape on one end then try to splice in 2 3" pipes into the end of it.

 

will try it out, but would be good if anyone has done something similar

 

Here is what I did on my Z:

http://forums.hybridz.org/showpost.php?p=625867&postcount=31

http://forums.hybridz.org/showpost.php?p=648128&postcount=36

[240zwannabe]

hows the ground clearance with the exhaust out the side?

[TimZ]

hows the ground clearance with the exhaust out the side?

 

I tucked them in between the ends of the frame rails and the sway bar mounts, so the clearance is within maybe 0.25" of what the frame rails have.

[240zwannabe]

I tucked them in between the ends of the frame rails and the sway bar mounts, so the clearance is within maybe 0.25" of what the frame rails have.

 

 

i'm sorry i wasn't very clear, i meant how much ground clearance is there from the bottom of the exhaust where it exits behind the door between the ground?

[TimZ]

No - you were clear - perhaps I wasn't. I was trying to say that they hang down maybe 0.25" lower than the frame rails.

 

Here's the pic again, it's kind of hard to see:

[240zwannabe]

oh, ok. i see now the only picture i was looking at to try to measure up clearance was the picture that has just the tip and the right rear wheel. thanks

[93anthracite]

that's a pretty sweet exhaust setup Tim.

Are you worried at all about any kind of strange flow/vortex issues with that? I personally think it will be fine, but I've seen arguments from people about odd shapes like that disrupting flow patterns (ex: gutted cat won't flow very well b/c of expansion of chamber and going back to restriction of pipe). Any idea if that is true and if it will affect your design?

My theory has always been to get as big a pipe as you can fit on any turbo car, so maybe that only applies to NA and hence has nothing to do with your setup.

[TimZ]

that's a pretty sweet exhaust setup Tim.

Are you worried at all about any kind of strange flow/vortex issues with that? I personally think it will be fine, but I've seen arguments from people about odd shapes like that disrupting flow patterns (ex: gutted cat won't flow very well b/c of expansion of chamber and going back to restriction of pipe). Any idea if that is true and if it will affect your design?

My theory has always been to get as big a pipe as you can fit on any turbo car, so maybe that only applies to NA and hence has nothing to do with your setup.

So far my new exhaust has been working very well, if a bit loud...

 

I instrumented the turbine inlet pressure, and so far I'm seeing TIP at about 2-6psi less than manifold pressure at 24psi of boost...