Mazda Talk Forums

The problem with ovalizing the exhaust tip is that you will loose cross-sectional area and thus flow. The circle is the shape with the lowest ratio of perimeter to area. Anything else has a larger ratio, so reforming a circular tube into any other shape will result in less area surrounded by the fixed amount of perimeter. I think it's better to start with an oval pipe of the desired area coming out of the muffler or to add on an oval tip of equal or larger area at the end of the circular exhaust pipe.

Unfortunately, most of the commercially-available oval exhaust pipe starts at the equivalent to 3" round piping and goes up in size from there. I don't know of a source for 2.5" oval pipe or 2.5" round to oval transitions. So you're probably right -- it would need to be a weld-on tip on a round pipe.

Another consideration is that the SA-G motor is tuned more for low and mid-range torque than the MZR and isn't really a high RPM screamer. It may be a candidate for a 2.25" exhaust setup, rather than a 2.5" one. That would actually open up the door for a lot more choices of fabrication parts to work with -- both mufflers and tips.

My guess right now is that best results will indeed be round tip and we will be using a single round tip.

Brian wrote:My guess right now is that best results will indeed be round tip and we will be using a single round tip.

I suspect you are right. I'd certainly optimize performance rather than appearance, and a single round tip would be the simplest way to get the desired flow. I'm looking forward to seeing what you cook up.

what if the exhaust tip was angled slightly (side-to-side) to help "fill" the cut-out? then add an angled tip for even more optical illusioning in the cut-out?

njaremka wrote:what if the exhaust tip was angled slightly (side-to-side) to help "fill" the cut-out? then add an angled tip for even more optical illusioning in the cut-out?

I like the creativity of your thinking, will certainly look at that option.

Interesting idea. Cutting a circular tube at anything other than 90 degrees will give one an ellipse. Looking at Brian's photo, one could run a pipe diagonally from the point where the muffler mates with the midpipe over to the cutout in the bumper, then cut it diagonally to create an oval opening to fill the cutout and be flush with the bumper. We can calculate the aspect ratio of the ellipse as a function of the angle of that pipe easily.

Assuming a 2.5-inch pipe, the vertical dimension would be 2.5 inches. The horizontal dimension will depend on angle:
60 degrees: 5.00"
45 degrees: 3.54"
30 degrees: 2.89"
0 degrees (straight back): 2.50"

I really like that idea. Gives you the oval look on the tip without changing the flow of the 2.5" pipe at all, and it doesn't require a tip that's going to add weight and cost.

Brian, if you work with any manufacturer to develop sway bars, please include 3 mounting holes on each end of each bar.

skeeler wrote:Brian, if you work with any manufacturer to develop sway bars, please include 3 mounting holes on each end of each bar.

I like that idea...