Brian's First ND Projects

Miata Parts, Intakes, Superchargers, Headers, Exhausts, Shocks, Springs, Sway Bars, Brake Kits, Autocross and track mods.
skeeler
Posts: 282
Joined: Mon Mar 31, 2008 7:31 pm
Location: Ann Arbor, Michigan
Contact:

Re: Brian's First ND Projects

Post by skeeler »

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.
2009, STR & DD. 1995, HPDE. 2004 MSM, sold. 2010 Mazda3, hers.
Chuck H
Posts: 154
Joined: Fri May 18, 2012 6:28 am

Re: Brian's First ND Projects

Post by Chuck H »

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.
2019 Arctic White RF GT-S
SmartTop, coilovers
Brian
Site Admin
Posts: 11307
Joined: Tue Feb 15, 2005 11:44 am
Location: San Diego CA
Contact:

Re: Brian's First ND Projects

Post by Brian »

My guess right now is that best results will indeed be round tip and we will be using a single round tip.
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
skeeler
Posts: 282
Joined: Mon Mar 31, 2008 7:31 pm
Location: Ann Arbor, Michigan
Contact:

Re: Brian's First ND Projects

Post by skeeler »

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.
2009, STR & DD. 1995, HPDE. 2004 MSM, sold. 2010 Mazda3, hers.
njaremka
Posts: 94
Joined: Fri Dec 17, 2010 10:31 am

Re: Brian's First ND Projects

Post by njaremka »

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?
Brian
Site Admin
Posts: 11307
Joined: Tue Feb 15, 2005 11:44 am
Location: San Diego CA
Contact:

Re: Brian's First ND Projects

Post by Brian »

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.
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
skeeler
Posts: 282
Joined: Mon Mar 31, 2008 7:31 pm
Location: Ann Arbor, Michigan
Contact:

Re: Brian's First ND Projects

Post by skeeler »

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"
2009, STR & DD. 1995, HPDE. 2004 MSM, sold. 2010 Mazda3, hers.
Chuck H
Posts: 154
Joined: Fri May 18, 2012 6:28 am

Re: Brian's First ND Projects

Post by Chuck H »

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.
2019 Arctic White RF GT-S
SmartTop, coilovers
skeeler
Posts: 282
Joined: Mon Mar 31, 2008 7:31 pm
Location: Ann Arbor, Michigan
Contact:

Re: Brian's First ND Projects

Post by skeeler »

Brian, if you work with any manufacturer to develop sway bars, please include 3 mounting holes on each end of each bar.
2009, STR & DD. 1995, HPDE. 2004 MSM, sold. 2010 Mazda3, hers.
Brian
Site Admin
Posts: 11307
Joined: Tue Feb 15, 2005 11:44 am
Location: San Diego CA
Contact:

Re: Brian's First ND Projects

Post by Brian »

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...
Brian Goodwin
Good-Win Racing
www.good-win-racing.com
Post Reply