Our New 2012 PRHT SS Project....

[mazdaracerchick]

I am SO Excited for these 17x7.5 Enkei RPF1 with the SBC finish...they are going to look amazing and are lighter weight which makes such a difference. Plus super custom since they are being made for us!

[Brian]

My Baby's MX5 is a strong one!

We have years of dyno work on the NC1 and today was the first time I got to play with an NC2 on the dyno. Mazda has a history of making lots of little improvements as production years roll past and not really giving up the details.....but every 2006 we measure on this same dyno is in the range of 130 at the wheels (remember that factory horsepower rating is at the engine and there are driveline losses such that what you measure at the wheels is much less), all the 2007 have been stronger, the 2008 about the same as 2007s. Likewise, they must have improved a few things in these NC2 motors because this MX5 is a few stronger than any NC1 motor we ever had on this same dyno...peaking 144 hp with stock exhaust, and just over 150 at the wheels with just a muffler change.

My plan today was just to a get baseline for the project car but we also took the opportunity to build and play with some more prototypes for up coming "SuperQ" replacement for the classic Q. Sharp eyes will see in the picture SOME of the differences in these units, classic Q at the top with smaller central chamber (I won't tell competitors here the precise size and shape and other details---let them do their own dyno work!), then below that is prototype with larger dump chamber, and below that is prototype with even bigger central 'dump' chamber and so on (see the weld marks), and finally the stock muffler at the bottom of the stack. Only the finished unit at top with smaller chamber really kicks butt over the stock muffler. It's really the same lesson we have learned a few times before with all our RoadsterSport exhausts, which is that gas velocity stall is the big thing to avoid in any NC muffler design. But that makes the factory muffler a real head scratch because it has a massive 'dump chamber' just inside the connection flange which is not efficient for gas speed.... and every time I try and copy some of that dump chamber size the dyno results really drop off down to stock levels....both torque in the low end and hp at the high end. The bigger dump chamber unit in the bottom of the photo just above the stock muffler turned a curve that looks much like the stock muffler. Only by keeping that chamber much smaller do we get BOTH the MUCH better low end torque and better than stock peak numbers that crush the stock muffler shown at bottom of the photo.....top line on the dyno chart is best run with Q, lower line on the dyno chart is best run with stock muffler.

So, why did the factory make that massive dump chamber? The answer must be the SOUND engineering that they wanted, and they sacrificed power to get the precise sound they wanted. My bet is that they didn't try the side entrance design we are using which I find equally controlled on sound, yet with a nicer little growl on acceleration.....and with more consistent flow.

[eluviis]

Wow. The best part is that apart from the big improvement between 6600 and 7300 the other big boost is at the low rev range. Very good to see.

[eluviis]

I do have one question for you about this car...

Even if you manage to keep the car strictly as a DD for the next 5 years, the natural progression for it after those 5 years would be... a heavily modified track car. I know this, because I highly doubt you are simply going to sell it and take a hit on a car that you know since it was a baby.

So... having said that... I'm sure you have given some thought to that PRHT and how it might come into play in your future decisions. I know it's a little early to think about that, but I have a feeling you have thought about it already.

Like... would you consider a custom roll bar setup ala Cyberbug? Or maybe modifying the top itself to be able to fit something taller under there (pushing the glass further back). Or maybe being able to remove the whole thing in it's entirety and fitting it with some some sort of hard top or soft top over a cage.

I would VERY MUCH love to hear your thoughts on this. As you are aware, I've been doing mod research for my car every since I bought it 2 months ago. However, I haven't bought a single part, or unscrewed a single bolt yet - Because I keep questioning my decision of opting for PRHT. You've may have seen the posts on my MX5 modding thread where I talk about Auto X and the possibility of looking into a Spec Miata later on. While I know I won't be tracking this car hard for the next 5 years, I want to know that after that time I don't simply have to get rid of it to get a soft top in order to really track the car.

I already sold a car to buy my MX5 that I fully regret selling. I should've kept it too (along with the MX5). I don't want to go thru that again. O.o

[Brian]

We have THREE other NC that are already modified for track and autocross. Thus, this project will stay pure street daily driver. Therefore, no plans to make PRHT roll protection.

[jboemler]

If you're thinking of "serious" track work in the future, the PRHT isn't your car. To be honest, unless you can bring serious money, the NC isn't your car. Back to the NA as a track car, really.

[AZ Sun Lover]

Hmm, I'm guessing your going with a 245/45-17 on the 7.5" wheel?

*My* .02 cents the mufflers look better not polished! Just use some Scotch Bright to lighten the browning of the stainless or better yet is getting them ceramic coated. I'm betting it's cheeper the having the stainless polished. Just some soap and a sponge the coating looks new after washing off road grime.

AZ

My bad I should have put 225/45-17's

[Brian]

Hmm, I'm guessing your going with a 245/45-17 on the 7.5" wheel?

*My* .02 cents the mufflers look better not polished! Just use some Scotch Bright to lighten the browning of the stainless or better yet is getting them ceramic coated. I'm betting it's cheeper the having the stainless polished. Just some soap and a sponge the coating looks new after washing off road grime.

AZ

Not near that much tire... That 245/45 tire is properly fit to 17x9. For this project will stay with 205 or 215mm

[Brian]

The RoadsterSport Street header is installed! Some of Rocky's install photos below, stock header about to come out....and prototype with converter going in.



Today we are flogging this project at its first autocross to really test the limits of the progress technology sway bars!

The car is a blast to drive with a sway bar upgrade but we are looking forward to getting some good coilovers. on this project. We already know we love Ohlins so which coilover should it be for this project? Perhaps KW this time?

[AZ Sun Lover]

Brian,
You have a little pull with Progress. (from my talks with an employee @ Progress) Why don't you ask Progress to make a few set's of front Progress springs about a .5" lower in ride height than what they make now.
Then install new Progress springs & Koni's.
Tire Rack tested KW's, and KW's are designed (one needs to look at their max ride height) to ride much lower than many MX-5 owners want to go. If one adjusts the KW's over their designed max ride height, you pre-load the springs & it's not good on the shock body. This is why I had to "test" many sets of MX-5 springs on the market out there now.
Just a thought on my part.

AZ