SCCAForums.com

A consistent topic in SM2 is the potential competitiveness of the NA/NB Miatas. I've driven competitive CS and CSP NA/NB cars, but don't know too much about the aftermarket support, engine strength, drivetrain strength and other strengths and weaknesses the car has as you modify it. I have an idea of what I would do if I was building the car, but I'd like to see other folks' ideas. I'm hoping this thread will futher educate me and others on the potential of this car. Here's a first swing:

Engine:
Built 1.8, 9.5:1 CR
Forged pistons, rods if necessary
Oiling and valvetrain to hit at least 8500 rpm
Cams if necessary
Appropriate fueling upgrades (rail, injectors)
Standalone programmable EMS
C12 leaded fuel in 5-gal cell

Forced Induction:
GT28RS turbo (proven to mid 300whp) or oversized twinscrew capable of 350whp
Necessary exhaust manifold/downpipe/etc
Front mount A2A or A2W intercooler with ice bucket

Drivetrain:
Multi-disc clutch ala CSP
Upgraded gearset (? - not sure what hp capability of stock is)
Clutch-type 1.5 way LSD
One of each final drive available (target 72mph at 8500 in 2nd, but possibly swap based on course)
Upgraded axles if necessary

Suspension/Tires:
275/15 Hoosiers
Koni 28 series or Penske double/triple adjustable coilovers
Heim joint suspension with A-arm/spindle adjustments to correct roll center migration due to lowering
Front splitter and yo-boys rear wing

This should produce something similar to a CSP car with twice the power, better gearing, and better suspension geometry. It sounds like I'd probably need to add 200# somewhere. The advantage of starting with this chassis is that I get to essentially choose where to put the last 200#, rather than have the manufacturer tell me where it goes. I'd look to fabricate any low-lying legal mounts, brackets, housings, etc. out of thick steel. Some nice 50# seat brackets would work well. Then I'd probably just plunk some ballast in the trunk as low and far forward as possible so it'd sit right over the rear tires. I think you could get the weight distribution biased toward the rear even, which would improve transitional response and help put power down.

If anything above looks silly to the hardcore Miata guys please point it out. This is a pretty basic SM2 build with mods/parts that most (if not all) of the top cars are currently utilizing. Nothing exotic. At first glance I'd guess this is about $15-18k in parts and engine work, which probably means a total investment of about $20k, including the chassis.

I'm hoping more knowledgeable Miata guys will jump in with some more outside the box ideas. I think I've gone "outside the kit" with this build which seems to be a prerequisite to making a competitive SM2 car. But there are always those guys that take it a step further. Things like using the new MX5 motor, or even a 3.0-3.5L na V6 seem very possible (think Vic Sias type power/response). Please share your ideas.

-Randy

---

Randy Noll

Pretty decent list, but $20K is low.  $30-$35K is closer to reality, unless you're an exceptional fabricator.

$2K - donor car
$500 - donor engine
$6K - mildly built engine
$2K - ECU
$4K - supercharger
$4K - shocks
$3K - control arms
$1.5K - wheels
$1K - tires
$2K - aero
$3K - Quaiffe gearset
$2K - rear diff & gearset

My numbers assume a moderate amount driver fabrication - using shops for some of the more critical stuff.  Assuming a second set of wheels for the dry and a set for the wet, you're pushing $40K.

---

Steve Garnjobst
#75 XP
'99 Mazda Mutant

Randy, that's a great build.  The only pitfalls I see is chassis rigidity.  perhaps your extra #200 would fall into a rollbar that may tie together at some points that need strengthening?  I haven't looked closer into what we can legally do with a rollbar, but it'd be a good idea to help strengthen chassis and eliminate flex.

Costs may depend on what contacts you have.  I think yours are a bit low, but Steve's are more in line if someone were to build it at retail prices.  Someone with good contacts could get it done between your and his quotes.

d 

---

Dan Pedroza
GS 127
WikiWiki!

What kind of shocks is Steve using?   Is it 2K per corner, or did he just type 4K for shocks twice on purpose?  Aero is overstated by about 1K unless you want to get an Erik wing, in which case it would be understated.

In any event, it would be a great car in the 30 ish range.   What's the problem?  Is there a 20K price point?

 -Andy M. 

 

Another question, are there any bolt on transmissions that would help (with minimal adapter work)?  New Miata transmission? I'd say RX-7 transmission, but not so sure that would fit in the tunnel.

 -Andy M.

sm2dan:

Randy, that's a great build.  The only pitfalls I see is chassis rigidity.  perhaps your extra #200 would fall into a rollbar that may tie together at some points that need strengthening?  I haven't looked closer into what we can legally do with a rollbar, but it'd be a good idea to help strengthen chassis and eliminate flex.

Costs may depend on what contacts you have.  I think yours are a bit low, but Steve's are more in line if someone were to build it at retail prices.  Someone with good contacts could get it done between your and his quotes.

d 

Great idea on the roll bar! I forgot all about that. I'd consider it an advantage to be able to put one in and still be under min weight. I bet you could get a stiffer chassis than the NC and still be lighter. Roll cages are outlined in Stock, SP, and in the GCR. It looks like you're allowed up to 8 attachment points. This should go a long way toward stiffening things up.

Keep the ideas coming.

---

Randy Noll

boxboy:

Another question, are there any bolt on transmissions that would help (with minimal adapter work)?  New Miata transmission? I'd say RX-7 transmission, but not so sure that would fit in the tunnel.

 -Andy M.

RX7 Turbo II drivetrain fits with an adaptor plate :)  very common, but not easy to come across the parts.  There have been a handful of people that have been selling their setups, but not at the right time..at least for me :)  that's the weak point with the NC.  Even the stock trannies are blowing on the stock engines!  Ironically, I believe that Ron's decision to ditch his 6 speed for the 5 speed cost him some usable torque at HPT this year.

d 

---

Dan Pedroza
GS 127
WikiWiki!

rnoll98:

Engine:
Built 1.8, 9.5:1 CR
Forged pistons, rods if necessary (WISECO / CARRILLO (rods are a MUST.  the weak point of a boosted miata motor)
Oiling and valvetrain to hit at least 8500 rpm (we drilled out our block at some passages for additional oiling/lubricating.  a set of beefed up valve springs to eliminate high RPM flutter)
Cams if necessary (not necessary at all)
Appropriate fueling upgrades (rail, injectors) (fuel rail and a set of RC 550cc injectors)
Standalone programmable EMS (Haltech, Emerald, Hydra...)
C12 leaded fuel in 5-gal cell (do you think its necessary?)

Forced Induction:
GT28RS turbo (proven to mid 300whp) or oversized twinscrew capable of 350whp (I'm a fan of the Opcon twinscrew 1.2L, but Jeremy Schuster turbo setup in '05 was very nice!)
Necessary exhaust manifold/downpipe/etc (definitely necessary)
Front mount A2A or A2W intercooler with ice bucket (mounting would be tight.  water injection would help.  Bell played with A2W intercooler but it was monstrous and just wasn't as efficient as the A2A)

Drivetrain:
Multi-disc clutch ala CSP (for the high HP cars, yes.  ACT heavy duty clutch kits can do the trick, though)
Upgraded gearset (? - not sure what hp capability of stock is) (RX7 Turbo II drivetrain (or) one of these http://flyinmiata.com/index.php?deptid=4531&parentid=0&stocknumber=08-90500 with a Guru Limited Slip Diff)
Clutch-type 1.5 way LSD (I never blew up a Torsen, but others have.  I think the Guru would work nicely :)
One of each final drive available (target 72mph at 8500 in 2nd, but possibly swap based on course) (see above link)
Upgraded axles if necessary (also included with the RX7 setup)

Suspension/Tires:
275/15 Hoosiers (YES!)
Koni 28 series or Penske double/triple adjustable coilovers (I'd pay Erik to tune mine, if i ever went these way again)
Heim joint suspension with A-arm/spindle adjustments to correct roll center migration due to lowering (Y'all should check out Keith Brown's DP setup.  woot!)
Front splitter and yo-boys rear wing (REMOVEABLE of course.  I'd have a spare trunklid :P)

---

Dan Pedroza
GS 127
WikiWiki!

Cosworth has some VERY trick stuff for the Ford/Mazda Duratec engines.  A complete 250hp 2.3L normally aspirated engine including IRTB intake system is a phone call and credit card away.  Don't know how much work it would be to stuff one in an NA/NB, but it should be very strait-forward for an NC.  Can you get an NC down to 2060lbs using SM allowances?  2060 lbs, 220ish RWHP, and 295 section-width tires would certainly be interesting. 

---

Once you go Mac, you never go back!

This is easy.....I think about this about once a week.

Here's what the build sheet for my car will look like when I'm Mechanically finished with the car. Some of these prices are based on me knowing some people, I can get a expensive Weld in Cage for $1000-$1300 compared to $2,500 my friend charges etc etc. Ohh and Dan, thanks for mentioning the Guru LSD, I will most certainly order one next month with my hard earned savings....damn it. Good news. ONLY about $22,000 to go!

Car	Price
1994 Mazda Miata	$4,400
Custom 8 Point Weld In Cage	$1,000
Total	$5,400
Engine
2.0L FM Stroker Kit	$4,099
1999 Head	$250
Valve Spring/Retainer Kit	$366
Oversized Valves	$368
Adjustable Cam Gears	$200
Port and Polished Head Install Valves	$1,500
Custom Cam, Same Duration, More Lift	$600
ARP Head Studs	$167
ARP Main Cap Studs	$116
Billet Steel Main Caps	$475
Coolante Reroute DIY Kit	$100
BEGI Twin Screw Blower Kit w/ A/A IC	$4,200
RC 650cc Injectors	$500
70mm Throttle Body Setup	$400
Link ECU	$1,000
WBO2 Kit	$300
Vishnu Fuel Rail	$220
75mm SC Pulley	$65
Custom SC Header 1 3/4" Primaries to 2.25 Collector	$700
Custom 2.5" Exhaust	$600
ATI Harmonic Damper/Balancer	$425
Oil Cooler	$300
Total	$16,951
Drivetrain
Guru Limited Slip	$1,400
Quaife 5 Speed Gear Set	$2,795
Light Weight Fly Wheel	$400
Heavy Duty Clutch	$350
04-05 Mazdaspeed Miata Oversized Drive Shafts (used)	$150
Total	$5,095
Suspension
Koni 28 Series Double Adjustable	$3,800
ISC 3 Piece Sway Bars Front & Rear	$800
Heim Jointed Control Arms (self fabricated)	$800
Relocate Pickup Points	$100
15x10 Wheels	$1,500
275/35R15 Hoosier A6	$1,200
Total	$8,200
Aerodynamics
Air Dam or Splitter	$300
Ricey Wing	$1,000
Total	$1,300
Grand Total	$36,946

---

Logan Murray
SM2 NA Miata

boxboy:

What kind of shocks is Steve using?   Is it 2K per corner, or did he just type 4K for shocks twice on purpose?  Aero is overstated by about 1K unless you want to get an Erik wing, in which case it would be understated.

In any event, it would be a great car in the 30 ish range.   What's the problem?  Is there a 20K price point?

 -Andy M. 

Listing the shocks twice was an error.  I was assuming 2800-series Konis.  For the aero, I was including a splitter & some custom wing mount fabrication.

---

Steve Garnjobst
#75 XP
'99 Mazda Mutant

sm2dan:

Heim joint suspension with A-arm/spindle adjustments to correct roll center migration due to lowering (Y'all should check out Keith Brown's DP setup.  woot!)

Keith is running a set of control arms from Jon Brakke.  Built for the rigors of EP Club Racing and refined over the past several years.  I'll be running the same setup next year.

---

Steve Garnjobst
#75 XP
'99 Mazda Mutant

boxboy:

Another question, are there any bolt on transmissions that would help (with minimal adapter work)?  New Miata transmission? I'd say RX-7 transmission, but not so sure that would fit in the tunnel.

 -Andy M.

After going through several 5-speed trannies, I've been using a Miata 6-speed for the past two seasons.  So far, it's held up great, and is only 8 lbs heavier than the 5-speed.  Gearing is a bit unusual, as I run a 4.44 rear end and use 2nd (51mph) & 3rd (73mph) as my autocross gears.

---

Steve Garnjobst
#75 XP
'99 Mazda Mutant

LeadFoot,

Thanks for the contribution. That's exactly what I was looking for. You're gonna have one wicked car on your hands. What's the hp target?

Like Dan did in the other thread, I'd encourage you to get the car on course ASAP and start working the suspension and getting used to the car. Your profile says -8GMT so you must be on the west coast somewhere? Come on out, help the class keep numbers up. It's always fun to be able to meet and watch guys as they build and get faster.

Steve,

I've always wanted a 2-3 setup like that. Ideal would probably be 60 in 2nd and your 3rd, but you're pretty darned close. It would be perfect for the west course finish this year, and even the middle portion of the east coast maybe. If you can make the shifts smoothly enough, you can really put that 2nd gear to use. A custom pair for 2nd gear might be an interesting option.

---

Randy Noll

MNbiker:

sm2dan:

Heim joint suspension with A-arm/spindle adjustments to correct roll center migration due to lowering (Y'all should check out Keith Brown's DP setup.  woot!)

Keith is running a set of control arms from Jon Brakke.  Built for the rigors of EP Club Racing and refined over the past several years.  I'll be running the same setup next year.

My suspension is not legal for SM2, you have to modify the subframes. Althought something similar could probably be done with a little creativity.

---

Keith
'90 Miata with a really big roll bar
www.chaserace.com
www.tightntidyracing.com
www.vorschlag.com

rnoll98:

...I've always wanted a 2-3 setup like that. Ideal would probably be 60 in 2nd and your 3rd, but you're pretty darned close. It would be perfect for the west course finish this year, and even the middle portion of the east coast maybe. If you can make the shifts smoothly enough, you can really put that 2nd gear to use. A custom pair for 2nd gear might be an interesting option.

I don't even use 1st gear on course - I launch in 2nd.  I can spin the wheels from a standing start all the way through 2nd gear, so 1st isn't necessary - even on a really tight course.  We just left the car in 3rd for the West course finish, and it worked fine.

-Steve

p.s.  Next year, the car will have a block-off plate to eliminate the possibility of accidently shifting into 5th.  Doesn't happen often, but is pretty annoying when it does.

---

Steve Garnjobst
#75 XP
'99 Mazda Mutant

rnoll98:

LeadFoot,

Thanks for the contribution. That's exactly what I was looking for. You're gonna have one wicked car on your hands. What's the hp target?

Like Dan did in the other thread, I'd encourage