PROJECT ND: Parts Development, Testing, Measurements, DYNO

Miata Parts, Intakes, Superchargers, Headers, Exhausts, Shocks, Springs, Sway Bars, Brake Kits, Autocross and track mods.
Brian
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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by Brian »

Got some questions about the stock muffler design so I will add some more explanation. In this case that sealed chamber with the orange arrow is actually dual purpose. The arrangement is not a true Helmholtz chamber, but the entrance to the chamber and the pipe into it are effectively a Helmholtz valve for the gasses passing out the perforated section, and you can think of that valve as focused on removal of particular 'boom' or 'drone' frequencies. The main purpose of that sealed chamber is accomplished by having the flow pipe pointed directly into it megaphone style, which is not about Helmholtz function, and what it does is make that sealed chamber act as a catch basin for all sound waves of all frequencies, making that chamber a very effective attenuation or 'mix' chamber. This way of doing it is very cheap and effective because that small chamber gets a lot done for very little investment in materials and weight... though smooth flow is highly compromised by pointing the main flow pipe into a sealed chamber. Smooth flow is the way to max the power result. Our ND exhaust designs use a true Helmholtz strategy, arranged as a side branch resonator where gases pass over the valve and the chamber is dedicated to Helmholtz function, an arrangement that does not interrupt the smoothness of the main flow pipe.
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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by Brian »

More SOUND MAPPING of the ND. Most our competitors just weld stuff up until they get the sound 'okay' but we do a complete sound mapping of the car under a wide range of conditions. We did this to develop our ND mufflers currently selling, and we have repeated the process with our prototype header because the header changes the sound so much. Lots and lots of driving the ND crammed full of computers and microphones. Do get a helmholtz chamber designed just right, need to map the sound with spectrum analyzer.

Yes...and a twin tip RoadsterSport Muffler is coming.
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SuperStreetTWINN.jpg
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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by Brian »

Fun weekend at Willow Springs Raceway for opening event of our sponsored time attack, the Roadster Cup!

Our Supercharged 2007 was on the trailer early with what we think was overheating ECU and that put THREE drivers in our ND for the rest of the event. Three drivers in our ND putting the spurs to it all afternoon in warm consitions and it performed like a champ. Ryan and Sean will be along to share their impressions.

Some of my highlights:

Mishimoto Oil Cooler....is required for ND Track Use. Before adding the oil cooler even autocross events got the oil north of 230 F and track events without oil cooling put it north of 250 F all too easily. Saturday surface temps 100 F and approaching 80 F in the shade, and even with THREE drivers doing back to back triple stints the oil temp was pretty constant at about 210 F. When I had my last NC engine built the Cosworth engineer told me their goal was always 209 F for oil and water as about ideal balance for long term performance and wear so 210 F is right where we want to be, water temp was also stable just a few notches lower.

FEAL Coilovers. I sometimes forget how rough 'Streets' of Willow Springs Raceway can be. We started too stiff and car was nervous, set tires and coilovers to much softer and car was happy to play all day. Spring rates 8k front, 4k rear with our Progress Sways set to tight front (innermost setting), rear outer most holes. Balance good, drifting evenly when pushed too hard, fun at the limit.

New KUMHO 720. First event on these and despite triple stints they never got greasy or had any issues, easy to drive on, consistent times, etc. Size 245/40 on 17x9 wheels. We rolled the fronts prior to event and still had to raise the fronts a little to stop rub. We should have rolled the rears, got a bit of rub there and raised to help the situation. Bottom line, we consider fender rolling REQUIRED for 245/40 tires on ND....and with that size we recommend starting heights of at least 13.25 inches center of wheel up to fender lip.
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GWR at Streets of Willow trimmed.jpg
ND at Streets of Willow BRONZE 6ULs.jpg
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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by Brian »

Brake Dust can be beautiful.
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ND 6ULs at Streets of Willow 3s.jpg
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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by ronbauer »

Hey Brian, how much of the fender lip needs to be rolled front and rear with the 949s?

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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by ABQautoxer »

I'm curious too.

On the front I didn't roll at all. On the rear, I did a moderate roll for about 14" front to rear, estimated. Only an additional 45 degrees from where it was stock and I have no rubbing at -2.1 rear camber on my 6UL with 245/40/17 RE71R.
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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by Brian »

We have about 2.25 negative front camber and 2.0 rear and needed aggressive front roll to clear the Kumho 245/40/17 RE71R, and mild rear roll. We actually didn't roll rear for first track day with this size shown above but found it was shaving the tire a bit at rear, so rear rolled after the event.
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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by ABQautoxer »

Brian wrote:We have about 2.25 negative front camber and 2.0 rear and needed aggressive front roll...
Really? I'm going to carefully inspect but I'm sure I haven't' had any fender contact in the front without rolling. I wonder what could be different such as bump stop engagement points. I actually have less camber but I'm sitting higher though I plan to drop the car this weekend on stiffer springs.
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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by Brian »

Might just be the deference in tire models but we had a LOT of front rub, even in just light undulations in the street surface (didn't get anywhere near full compression or the stops). On our ND the Kumho 245/40 rubbing front fenders at 13.25 front height with about -2.25 camber before we even got out of our parking lot.
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Re: PROJECT ND: Parts Development, Testing, Measurements, DY

Post by ronbauer »

When you say "agressive" are you meaning that you needed to roll way beyond where it already has a slight roll or just that it needs to be tucked up against itself? Or are you saying that it has to be rolled to the point of not being STR legal?

Ron
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