Supermiata ST6/TT6 Build - Miller
 

https://cimg4.ibsrv.net/gimg/www.mia...a3ab259dfb.png
Miller was named for the 2013 NASA Championships at (then)Miller Motorsports Park in Utah. Sonny & Miller won TTD and placed 3rd in PTD at those championships.

The car is a 2004 Mazdaspeed Miata. Before being named miller, it was an early development example for turbocharged track miatas but was eventually de-turbo-ed for w2w racing.
https://cimg6.ibsrv.net/gimg/www.mia...62a69c7d89.jpg


Following that 2013 Champ effort, Miller was immediately used as one of the first Maxxis Supermiata Cup S2 cars, as well as a typical "949/Supermiata formula" HPDE/TT trackday car.
https://cimg4.ibsrv.net/gimg/www.mia...daaed653ea.jpg


Rules can be found here : https://www.nasaproracing.com/rules
An ST6/TT6 discussion thread can be found here: https://www.miataturbo.net/race-prep...st6-tt6-97655/

With NASA's replacement of the Performance Touring series with a simpler Super Touring ruleset, we've decided to build an ST6 car.
There are six Super Touring classes—Super Touring 1, (ST1), 2, 3, 4, 5 and 6, with ST1 being the highest performance level class of the six, and ST6 being the most restrictive.
NASA's Super Touring is a power to weight ratio class, with modifiers for certain chassis characteristics like A-arm suspension and light weight.

ST6 is an 18:1 base ratio, below what PTE used to be.
Engine swaps are allowed, provided the donor was a car that would also be allowed into the class(max power rule).

Miller's build will take the following mod factors:
18:1 class base
A arms -.7
BTM aero +.4 (Credit for base trim model aero. We will not be using a front lip, airdam, or spoiler of any sort)

Comp weight mod factor will either
Less than 2450 -.4, or
Less than 2550 -.3, depending on the power we can squeeze.

So, we're going to target 18.6:1 at 2450lbs which is 131 average whp, or 18.7:1 at 2400lbs which is 128 average whp.

Because these power figures are relatively low, they would be reachable with very modest power plants...

https://cimg9.ibsrv.net/gimg/www.mia...05af632c55.jpg

Is this the car that pissed off people because the rest of the field didn't know it was an MSM?

Why?
Well, the NB2 has the best OEM BaseTrimModel aerodynamics. The NB2 front bumper shrouds the most front contact patch for drag reduction. We'll do an undertray behind the bumper skin to the full extent of the rules.
Because any healthy Miata motor can hit ~131whp, we can use the lightest available Miata motor.
Because ST is average power based, picking the extra midrange of a VVT BP6D or the BP4W's slight peak power edge is less advantageous.
The B6 is about 40lbs lighter, and smaller physically, so it sits farther back in the wheelbase. The extra weight off the nose is noticeable and helpful. It should turn better than any 1.8 at the same power level.


Full build list:

2004 Mazdaspeed Miata "MSM"
-de turbo'd
-B6 swapped
A arm suspension (-.7:1)
BTM Aero credit (.4:1)
2450 at 18.6:1 (-.3:1), or
2400 at 18.7:1 (-.4:1)
205 R7 on either 8" or 9" 949 Racing 6UL wheel, depending on final comp weight.

We want to hit our 131avg whp goal on 91 octane pump gas(California's "premium"), so we'll be doing a couple things to the engine.
264/256* Kelford 203B camshafts
Toda lash adjusters to allow ~75-7800 rpm.
Megasquirt MS3
Intake/Header/Exhaust

Beyond that, the chassis/suspension will be:
900/500 Supermiata Xida Race
1.125" Racing Beat front swaybar
14mm Supermiata rear swaybar
We will convert from ELBJ to offset bushings to keep away from the .2 penalty for "modified, adjustable, or altered control arm ball joints"
Energy Urethane control arm bushings

OEM Sport brakes
G-Loc R12 front, R10 rear
Supermiata stainless brake lines
Motul RBF600 fluid

Supermiata tuned OsGiken LSD
4.77 or 4.875 ratio, depending on what rpm we feel is safe/necessary with the B6.

Yiss, dis is daewae my brudduh.

That was Crusher.

What does the 4.875 r&p come out of? Unless it is a custom/aftermarket part of course.

e:
Are you going to push the motor/trans back till the head almost hits the firewall as well? Seems like it could be a lot of money for minimal gains...but allofit.

Aftermarket. It was the last one sold by Mazda a few years ago. Maybe they have them again, dunno. B6 doesn't rev very high and has narrow powerband compared to BP. So gearing will be critical. It's something we spend a lot of time dialing in.
Most club level teams seem to ignore gearing.

How many points for Sonny mod?
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I think the BOP will be another 200lbs

I am so turned on right now. N/A B6 in an MSM. I don't think a phrase could be more fill with herracy.

A cat for you good sir.

Short nose crank for extra lightness?

C'mon. We're not "CrAzY"

I won't be happy unless the motor is pushed back till it's touching the trans tunnel and the shifter has some kind of odd remote linkage to use the unmodified trans tunnel opening.

Who here had that awesome quote about replacing a 1.8 with a 1.6 just to piss people off? Was it Rleet? haha.

FOUND IT!

​​​​​​​

Yeah, but the 1.6 is more revvy!

As someone who has made the choice to stay 1.6.... I really wish that were the case... The BP4W I have in my 99 beater is way more happy to rev...

But, the B6 is supposed to have all the revs? Do you even know miata engines, bro?

Bruhhh. It revs to the moon and back. The 1.8 is the infuhrur revving motuh.

Ports in B6 are tiny. Flow as ratio to displacement is inferior to BP. Even B6 FP motors (huge cams) make peak power at lower revs than BP EP motors. This is something we learned when I was helping Oscar Jackson tune and develop our B6 STL motor for 2014 runoffs.

Because of the better rod ratio and lighter reciprocating mass we plan on using a complete bone stock bottom end and spinning it to 8k at most.

Would there be any benefits to running a European 1.6 NB head and intake manifold? Did they make any improvements?

Dunno. Dyno and let us know what you find out. We're just sticking cams in it. Easy button.

It's of no benefit to me since I would never run a 1.6 but I'm surprised you don't know the answer since you know everything.

I can answer that, because i actually DO know everything.

NB 1.6 head casting is same, but it has solid lifters and a different intake manifold. The main advantage there is that it uses normal NB throttle bodies so you can use the Junk2 stuff. It also has NB ignition triggers so you can have more happy.

For the ~$200 it costs to get a manifold/tb/valve cover/cams brought over, i would highly recommend. Then use whatever year oil pump (i think all long nose should have it) for the crank trigger and voila, run that 1.6 like it's a BP4W.

Ah, didn't know the NB6 had solid lifters. You sure? Saves us the expense of fitting solid lash adjusters.

It do. Could also just snag some late KL buckets out of the junkyard too, since they are same. Probably not your style though, swagboi. :riaa:

I knew it had solid lifters. It's also got what is purported to be slightly longer intake runners. Presumably that was for more mid-range torque on the heavier NB cars though the peak rating is almost identical. That may or may not be a good thing on Emilio's race car build. Perhaps I should Dyno it and find out for him, lol.

I guess we will find out. Having never had an NB6 engine in our shop, we are in the dark. If there are indeed, significant dimensional differences between the two manifolds, it would be SOP to dyno. So yeah, we'll see.

There be. Pretty easy to see just looking at them.

Swapping for dyno sounds annoying because you can't swap throttle bodies between the two, though. (At least not super easily) 2/10 would not bother.

Interested to see what this car will make with the benefit of the NB 1.6 head. Maybe a record for a naturally aspirated non whammy engine incoming?

So is an N/A 1.6 the ultimate final stage of the mt.net cycle of life?

Uh, no. We need to make something like 131whp average. Goal is to make that on CA91 so we can run enduros and generally make logistics easier. Cams are pretty mild, street grind. Stock compression. We have made 128whp on a bone stock NA6 motor with I/H/E ECU and corn.

If there is any low hanging fruit, we'll implement it but otherwise not spending a bunch on this project. Sorta defeats the idea of an ST6 car if we go mad dog with a $14k race engine. No, we paid $1000 shipped for a fully dressed JDM NB6 and 5spd. If it has good compression / leakdown we'll leave the head on and just drop the cams in. If the leakdown numbers are not good, we'll do an OEM rebuild and deck the block for around 10.0:1 CR. While the head (might be) is off, we would bowl blend and do a nicer valve seat cut. In either case, the bottom end is all OEM. No need for forged rods, billet oil pump gears with the better rod ratio, lighter pistons, low BMEP and relatively low rev limit. So best case, we spend around $1800 total. Worst case about $4400. In either case, we plan to sell the motor at the end of 2019. If our formula proves successful, the motor will bring a few bucks to offset costs.

lol. Just a low budget side project. Sonny's race car has been mostly sitting around collecting dust. We thought it would be fun to do a relatively low cost ST6 build and share the whole thing from the start.

Vegas is the cycle of life :)

Miller had its final weekend in non-ST6 spec.

It is shipping off to Renderos Racing for body repair, cage updates and Cartek Solid State kill switch install.
https://renderosracing.com/

When it returns, it will have freshly painted OEM BTM aero bits(trunk, front bumper and a Singular vented hood) and ready to receive it's new heart.

https://cimg8.ibsrv.net/gimg/www.mia...bbdc8a6423.jpg
https://cimg9.ibsrv.net/gimg/www.mia...42760749eb.jpg

The #BTMAeroing has begun.
This is some not-so-sexy behind the scenes work, but crucially, the .4 BTM aero credit helps us stay closer to the class max 18:1 P:W, after taking a big .7 hit for having good suspension design.
https://cimg2.ibsrv.net/gimg/www.mia...60ac8dea1.jpeg



Renderos Racing is also adding a few attachment points to the cage, behind the firewall, to the extent of NASA ST and SPM S2 rules. SPM S1 and NASA ST both allow going through the firewall, but ST penalizes it with a hit to the adjusted P:W.
https://cimg5.ibsrv.net/gimg/www.mia...87761391c.jpeg
https://cimg6.ibsrv.net/gimg/www.mia...cd92d4af6.jpeg

Any door-sill attachments for the cage?

Yes.

Drivers side was done for PT.
Passenger getting replicated now that the rules opened up.

In for updates on NB6 motor/head as I'm eyeing one for swapping onto my NA6 bottom end. Did not realize they used the NB throttle body, though I know the mounting flanges were angled up relative to the NA6 TB to use the 1.8 intake tube while clearing the upper rad hose.

Dan, with the 4.77 R&P I assume 5sp trans?

Because it's mated to an engine that did not have an option of a 6spd from the manufacture, yes it will have to be a 5spd ;)

Ahh ok, wasn't sure if trans was tied to chassis, motor, or unrestricted.

nice
interested what you gonna do with engine
i have EU NB2 1.6 that i dont plan to turbo
or do anything really with engine
maybe MS and flywheel
if you need photos/measurements of something to compare just say

The car is a NB Miata, it can run any OEM transmission including the 6 speed. The motor swap opens up Non-OEM transmissions that come with the donor motor. They can run a 6 speed if they want to.

Hrmmm, I read the below as if the engine your using didn't come with 6spd as an option, you can't run a 6spd. Orrrr maybe the NB EUDM/JDM 1.6 had a 6spd as an option?

It's easy to read that rule as an either/or. As in, EITHER you are allowed the same transmission that came attached to the engine you're using, OR you can use the OEM transmission that came in your car.

If you wanted to write a rule that said "must use transmission that comes with engine", you would just write that. You wouldn't add "Otherwise, the transmission must be OEM" at the end.

2019 rules are official, Calculator is live.
https://form.jotform.com/drivenasa/s...ification-form

My napkin math was good.
We'll be aiming for:

2455lbs (-.3 Weight Factor)
132 average WHP
A arms (-.7 adjustment)
BTM Aero (+.4 adjustment credit)

18.60 Raw P:W
18.0:1 Adjusted P:W

OEM Sport brakes
OEM 6 spd allowed
Gear ratio open
OsGiken allowed

We will try to hit our power goal without touching the bottom end, and without using ethanol. We'll be using CA91, which is far inferior to the 93 in the rest of the country.

Should be doable no problem. I hit 141 whp on a Mustang on 93. 949 suggested intake, RB exhaust, Skunk 2 Manifold, MS3PNP.

Otherwise that should be a great fit for that class.

B6 vs. BP Engine Bay Position
 

Last night, I nerded out and did some measurements. Found out the B6 engine will sit 1.25" further back in the engine bay compared Miller's BP5A engine. Combine that with the B6 weighing less than the BP5A, Miller is going to turn-in hard during its NASA ST6 debut.

https://cimg4.ibsrv.net/gimg/www.mia...9c2081bc79.jpg

https://cimg3.ibsrv.net/gimg/www.mia...cf281ff6b3.jpg

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https://cimg8.ibsrv.net/gimg/www.mia...16fb116b90.jpg

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I'm curious to see how this goes!

Renderos Racing did the Cartek install and paint work, as well as the additional cage bars and gussets allowed in ST.

Minty OEM NB2 bumpers are swapped on.
Hardtop now matches OEM MSM Velocity Red
Fresh driver's side door
Headlights lenses were painted MSM Ti Silver, because more MSM heresy.

Also,
B6 is in.
Racing Beat NA6 header with a custom midpipe back to the same Racing Beat PowerPulse muffler.
Old reroute swapped for a Supermiata QMax Reroute.

https://cimg6.ibsrv.net/gimg/www.mia...82138b35d.jpeg

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Teaser:
https://cimg3.ibsrv.net/gimg/www.mia...8d115ce7fb.jpg

I see this strapped to a dyno.

Safe to say the numbers are where you need them to be?

Safe to say we are removing all the ballast for this weekend. LOL

Cams should be here next week. We're going to need them :P
Also plan to A/B with the NA6 IM


https://cimg1.ibsrv.net/gimg/www.mia...398fef788c.jpg
:(

It's such a cute baby dyno!!!
Interested to see how the A/B does with the NA6 manifold.

I know that @Twibs415 massaged a few NA8 intakes and we saw improvements across multiple higher mileage (100k+) NA8s on the Dynojet up at TFB in Sonoma.
The modified intake and stock exhaust made about 3-5hp more than the stock intake and RB header.
Never did get to A/B/C the two parts on the same day, but the end result was 136/112 or 134/119 depending on where we had the timing set on the intake cam, using 91 octane.

Daaaannnnggggggggggggggg big pawr!!

As the owner of (what I presumed to be) a tired 224k-mile NA6, I am comforted by that dyno graph. I made 103whp/97tq on 87 octane, stock AFM/intake, stock ecu, and an ebay header with a stock cat. Graph looks remarkably similar to mine, nosing over at 6500 with torque peak at ~4600 (also on a Dynojet)

Maybe the NA6 AFM isn't that big of a restriction after all? Was this with the stock TB on the NB6 mani?

When does the build on the B6 happen for it to make the needed 135ish rwhp?

I'm guessing the aforementioned cams will be part of that equation. Cams and aggressive head skim for compression bump would probably get it there, along with perhaps a bigger throttle body.

As mentioned in the OP, we hope to be able to run Enduros with this car. That means low enough compression to stay on pump gas for the much greater fuel economy. We will still run E85 for Sprint and TT.

With an almost identical set up and a Mazda crate motor we made 125 whp a few years ago. So this output is anomalous. I feel is either a different cam spec or the intake manifold design on the NB6. We will find out

If you're healthy NA6 motor is making less than 110 with the exact same setup, you need to rebuild the damn thing.

NASA SoCal Round 1 WSIR ST6/TT6 results
 

Full report and epic race videos later tonight. Good results (better than I expected) considering 110whp (107 avg whp) and 2180 lbs. Nowhere near true competitive form yet, but shows great potential for development for Round 2 at Buttonwillow in April.

For now, the summary is:

ST6: 1 win Saturday, P4 Sunday (photo finish, tied for P3 at the checkered flag according to timing/scoring, but tie-breaker goes to leading car before the finish line).
TT6: 1 win Saturday, P2 Sunday (lost by 0.059s)

Saturday ST6 results: https://racehero.io/events/socal-nas...lts/1073744183
Sunday ST6 results: https://racehero.io/events/socal-nas...lts/1073744185
Saturday TT6 results: https://racehero.io/events/socal-nas...ults/536871623
Sunday TT6 results: https://racehero.io/events/socal-nas...ults/536871626

https://cimg2.ibsrv.net/gimg/www.mia...28b7d7521.jpeg

https://cimg6.ibsrv.net/gimg/www.mia...6507e2352.jpeg

Miller's First ST6 Race
 

Race 1 video up. One of the toughest battles to win in a long time for me. There's a tap that sent me off the track that could have been the win for me outright. It didn't matter as the win happened by the unofficial winner DQing in impound for weight, but I'll take it. Still, there's more work to do if Miller wants to go win at Nationals.