open thread for the serious autox crew
 

Background: after 20 years of occasional autocrossing, I am going to be taking it more seriously next year; attending divisionals, a national tour, all regional events, an evo school or two and maybe a pro solo. Then maybe lurk at nationals in a year or two when my kids can travel better. I wanted to create a thread for guys serious about running the two classes that welcome turbo miatas, XP and SSM. I am hooked after getting an ftd at a corvette club event, then my co-driver getting 2nd fastest time of day at our regional a week later (I was .8 back), all while street driving my NT01s, which are not even the preferred autocross tire. Next year I want to be a threat for ftd at every regional event.

I want guys that run at the pointy end through the cones to weigh in on their setups. I know that Chris Swearingen sometime posts on here, he has what is demonstrably the fastest SSM miata in the country. I am sure there are other guys lurking here with fast autocross cars.

Stuff that is on my mind for next year is: 1. what's the biggest autox rubber I can fit under a rolled fender, are the 275-15 going to work, or should I stick with the 255-13 and adjust final drive to suit. 2. rules stuff, for example, I don't think I can run my frame rails, have guys run door bars instead with good results? 3. I want to run an aggressive map for autocross with race gas. Are guys running dual maps for two fuel types, pumping out their street gas on site, and filling up with race gas? I will be running a built probably 1.6, should I run water as a power adder, instead? 4. I am still going to street and track drive this car, anyone else doing so? 5. Diffs, I will probably go with a torsen 4.1, anyone switch from the torsen to the OS Giken, should I skip the middle step? I'm not really looking for answers to all of this, I will be trying and testing, but I want a discussion in this forum.

Discuss openly. This thread is about raping Elises, Z06s, S2000s, Evos, STIs, M3s, 911s......

I can only comment on two things.

Emilio said that you can run his 15x9 6UL with 275/35/15 rubber with a fender pull and roll, remove some liners and likely a 1/8" spacer to clear the control arm. And, I think 2.75 springs will rub. 2.5" are OK.

Frame rails are technically off limits in SSM. I ran mine, but I'm generally battling to stay out of DFL in SSM so nobody cares. I just run my RS3's so my lack of tire (and lack of skill) negates my slim chance at a trophy.

Well, I don't know how i'd do nationally, but i've been swapping first place finishes in my region (Atlanta = 200+ cars per event, usually about 10 in SSM) with a very well prepped C4 'Vette. Our cars are complete opposites too..mine is a daily driver, puts down ~260rwhp, running on 215-40/17 Kumho V710 this is my first year of autoX and I arrive at an event I just throw my slicks on and go..never check tire pressure, never cool down tires, run a pretty simple alignment. My comp. is running a trailered-in C4 'Vette on 315-35/17 Hoosier A6s, been autoX'ing for 20 years, makes constant tweaks to his car between runs and makes ~380rwhp.

The Hoosier A6 in 275/15 are the tire to go with. If I could run them..err afford them, I would. You are correct about the frame rails. You might get away with leaving them on for regional events if you're not killing everyone else/ giving them a reason to have officials poke around your car. If you are beating the snot out of everyone, better be playing by the book. I don't think the rollbar is allowed to have any extentions that "add chassis ridgidity". They understand that a lot of Miatas are DD cars and do allow a standard rollbar, but the front-runners only see that as extra weight and mostly don't use them. I'm running a Boss Frog Double Maxx, which has more attachment points over a Hard Dog...no problems here, but I really haven't checked the rules word for word...yet. As for maps and power...it's only as good as your tires will allow. Recently, I found out that i'm pushing the limits of my stock Torsen. Under hard cornering and acceleration, I can spin the inside wheel and not because it's lifting..it's because I have soo much grip from the V710s. In my case, more power is NOT the answer..a better diff or maybe some aero (which I plan on getting a "custom" APR GT-II aluminum wing ASAP). The 275s will only make this problem worse. OSGiken and Quaife offer nice aftermarket diffs., though finding a GURU would be awesome.

If you're looking to build a front-running SSM car for your local/regional events and have a fun DD, it's not too hard...but to be remotely competitive on a national level, you're going to need a hard-core not-very-friendly-for-daily-use machine...unless you plan on going to those events for fun. There are a few FD RX-7s that run ProSOLO/Nat's that are God-like in their speed and building a Miata to run with them will be quite difficult..but not impossible.

Great info, Doppel and Stein! I'm not thinking I am going to be nationally competitive, but again, I want to threaten ftd at regional events. We have a small region with, at this point, no other ssm cars. Unless a guy with a cmod car shows up, the fastest cars are an sm evo and sti, a csp crx, a fp stang and a ep integra. On our fairly short courses, 30-40 seconds, all these cars, including me, are within 1-1.5 seconds, with me being on the slower end.

I think with a little driver training, a little more driver training, those meaty 275-15 A6s, a torsen and some suspension work, I should be where I want to be. Anyone here actually running the 275s? I'd love to get away with them with just a pull and roll. I have a call in to Emilio to see if it's possible, and I know he has a pic on his site of an NA with them on it with a pull and roll, but it looks really iffy on the back. I'm thinking of flaring, but to make it look ok with my street wheels and tires, I think I'll need some spacers. At the end of the day, I'm just scared to cut my car up like that!

Welcome and I hope to see you at some events. I run a good number of east coast National events and Pro Solos and always go to Nationals. Definately take an EVO school! It will take you to the next level if you have hit a ceiling, and I just might end up being your instructor depending on where you take it. I have spent the last 7 years in a CS/ES Miata and last year ran Pro Solos in a friend's SSM 3rd gen RX7. I will be in the RX7 for Pro Solos, Tours and Nationals this year. I own a turbo Miata, but have a hard time believing they can keep up with the FDs, but I'd love to be proven wrong. The car I will be driving all next year just happens to be the 2009 SSM championship car. :)

As for your questions, for the fastest setup run 275 on 10" wheels which will require cutting the fenders. I'd build a 1.8 rather than bother with the 1.6. It has more power and you will probably never be able to get to the minimum weight anyways. On the diff, skip the Torsen. They are no better than an open diff if you have enough grip to unload a rear tire, which you should. The OS Giken is the way to go and I think the 4.10 ratio is probably best.

Brian Johns

Damn Brian, thanks. I noticed Evo just posted the early 2010 schedule, I will probably sign up for the school in May at Devins, Mass, then run the northeast tour, whether it ends up at Devins or Seneca (I'm hoping for Seneca, because the family likes to vacation out there, anyway). It's early to start talking about 2010 without the full sched being out, but keep me posted as to where you will be, maybe you can sit with me at Evo if you are going to Devins. Oh, and on my list of fast local cars, I skipped a certain DSP E30 that you may know of from National podium fame. A.S. doesn't show up to many of our regional events, though, maybe the surfaces are too bumpy for a real national level car?

Anyway, thanks for the tech tips. These are things that deep down I know, but am avoiding ($$$$$$$$). In the end, it's probably cheaper to do it right the first time, right? When I am still roasting the unloaded tire with the torsen at a tour event, I will be sorry I didn't spend the extra (only) $6-800 for the Giken. When I am going really fast with my 1.6, I will be sorry I didn't spend the extra (only) $1k on a built 1.8.......

The OSG diff. runs about $1400 for just the part..then comes install and while you're in there, might as well put fresh bearings in there. In the end, you're looking upwords of $1800-$2000 for everything..and that's with having a 1.8 7" rearend to start with. If you're looking to have "fun" and but mostly to have an even more fun DD car, a Torsen won't kill you and if you decide to do any open track days/ PDX, the Torsen will be right at home.

As for the 1.6, You should be able to make more than 209rwhp on a 2560R ;)

Once again, everything goes out the window if you're seriously wanting to be serious.

++1 on price creep. I do want to have fun, but I want to be fast at the same time. I had some fun in my HS corolla, and street prepared rabbits, but being at the fast end of the sheets is addictive! I feel like Bob on enzyte, I have a spring in my step, and I am more cooler!

That 209 was at 12psi, hot day, operator stopped at 6800. Figure that's good? I'm thinking of posting my plots and maps, and have everyone pick them apart. Maybe I'll do that tomorrow. In fairness, I asked for a conservative tune, because I just want it to hold together while I flog hell out of it at track days, and that's pretty much what I got. But, I want to be able to turn it up for autocross. As it is, I'm running right off the 'gate spring for track days, then adjusting with the mbc for autocross at around 14 psi.

Webby is your motor stock?

I auto-X in STS with a 88 MR2 so I don't know if I would be a good source of info on car setup for SSM or XP.

Stock motor with what the p.o. tells me was around 100k. He rebearinged the crank, and resealed/regasketed, but no rod, piston, or cylinder work. Head is untouched.

XP and SSM are really worlds apart when it comes to allowances. For the most part, all that XP requires to remain "stock" are the floors, firewall, rockers and tulip panel, and the engine block and head castings. There are some limits on minimum track and wheelbase, and some safety requirements on fuel plumbing and rollbars, but it's really an all-out fabricator's class. SSM is the class you want if you are limiting yourself to bolt-ons, not that fabrication doesn't exist in SSM.

With turbo power, go for the 275 on a 10.5" wide wheel. You'll want the additional footprint. I'd use the 4.1:1 for a turbo car. I'm using a 4.78:1 in my NA car.

I'd run every legal method of tightening up the tub that's allowed until I exceeded the minimum weight.

I'd run a torsen or torsen-style diff. The OS Giken is a clutch diff. They behave very differently and affect corner entry very differently. My experience with clutch diffs in autocross is that they add lots of push on corner entry.

Actually you can run any motor you want to in the chassis in XP as long as you meet the weight requirements.

Get a 1.5way diff. A 2way diff will tend to create a push when it locks under decel. The 1.5way allow for more slip between the tires under decel which allows for a better turn in. As SBrian2 stated, a Torsen is useless at the high grip levels of SSM.

SSM is not for the faint of wallet. I'm going against SBrian2 and attempting to build a competitive SSM Miata. Luckily I get to compete one-on-one with him and his car owner, so I'll have a good bench mark from the get go. Loosing the weight off the car is going to be difficult parts. I aim to get back to the STS trim weight of 2150 before I start going nuts to get down to the 2040 range.

IIRC the minimum weight for a 1.8 turbo Miata in SSM is 2240 and 2220 for a 1.6 turbo(including the 275 tire weight exemption). Since my car is my DD and I like to have an all around nice car, I have no plans for taking off any weight...I mean, I could probably find that 200lb, but I won't ever be nationally competitive in my car so there is no point.

Weight formula is 1800 lb + 200lb per liter + 1.4L for the turbo. So that's 1800 + (1.8x 200)+(1.4 x 200) or 1800 + 360 + 280 = 2440 - 200lb per tire exemption = 2240

Over on the pointy board, FatherLeadFoot has some good posts about diffs and how they act on a tight autoX. He went from the Torsen to a RX7 clutch to a OSG. He said the RX7 diff. set with a 160lb preload caused a good bit of on-throttle push and could still spin the inside wheel under some circumstances but that the OSG unit was controllable at all times. Unfortunately, the OSG unit when all is said and done is rather expensive...but since the rules allow such parts, they're pretty much a "must have" to be competitive in SSM.

Personally, I think my car with some aero, the OSG and 275 A6s, I wouldn't be that far off , but the two biggest things to increase grip...tires and diff, are some of the most expensive parts for me to buy. I also know that with such things, i'd be whooping up on the C4 'Vette that I run against locally :vash:
But i'd be looking at $2000 for the diff, $780 for some 15x9 6ULs , $1100 for the tires $250 for the wing and $150 for a custom front splitter.

Wow, good to know i'm not going to be competitive next year in SSM in my car lol. I kinda suspected this anyway.

I think I may get our Integra prepared for a stock class if I really want to compete in autox next year.

I popped my 1.6's tune up in the dyno section, if someone wants to see if I can get moar powah out of my mouse motor. I am doing something fresh under the hood for next year, not sure yet what it will be.

Fixed that for you.

A couple of quick things
10.5" wheels are better than 10"
275s are a must
You will have to cut the fenders to get low enough
I am running a 3.90 rear end and thinking very hard about switching to 3.63

Most of my stuff is posted on my site 51 SM2

Sorry all this is short and kind of shotgunned. I am on a business trip this week and pretty tight on time.

I am glad to see more miatas expressing an interest. Obviously I have a lot of faith that the platform can be competitive in SSM.

I subscribed and will try to stay current with things but expect more detailed updates next week.

Cool that you guys have such a deep ssm pool there in Tenn. Guys, what's the deal with the fd at nats? The one that Brian Johns is driving was not the only fast fd this year. Those were all n/a, right? I know with the right port work, the rotary can go mild to wild and everywhere in between. They also have less of an issue fitting large rubber, correct? And maybe they can be run lower than the miata? It may not be all about weight, as the fd Brian Johns will be in next year was not as light as it could be per the rules. I do know there were weather issues during the runs, though, could have effected the outcome.

Midtenn, I looked and didn't see anything on your build. Can you fill us in? FI or na? Turbo or blower? V6? 1.8? Judging from your target weight, it looks like a 1.8 turbo, but... Also, what for suspension, wheels, tires, diff?

All FD RX-7s were twin turbo (at least in the US). At least one of the big dog FDs runs a 3 rotor engine.

Your car is set up very similar to mine, except my soon to be FCM revalves and (maybe) my NT-01s.

Chris, thanks for weighing in. Don't think I haven't already checked out your build page thoroughly! The best of everything, maybe something I can shoot for in the future. Are you really running out of gear to the extent that the 3.90 isn't cutting it?

Things I know: I will run the 275 hoosier next year. I will probably run the 9" 6UL. I will attempt to roll and pull the fenders to clear, but will use flares if I have to. I am running the fcm non adj revalves with 550/350 (light comparitively, but a start). I will be getting a diff, but it will probably be 4.1 whether it's my open filled with an os giken, or a torsen. I will have a freshened engine, whether it's my 1.6 built or a 1.8 lb, built a bit less to save a bit of ching.

IMO that is too soft for the grip of the 275 A6. You will need much stiffer springs/shocks.

It is. I still want to drive this on the street, and to/from autocross and track days. I will rock the 550/350 next year.

I started a thread on mnet for folks to weigh in on streeting a serious autocross car. Hollis weighed in that a 750 front can still be street driven, with the right shock (very important) and a softer tire. If the 550/350 isn't heavy enough, and my kidneys are still intact (shitfuck NE roads), next year I will send the billies back to Shaikh to revalve for a more manly spring, along with the DA can$, of course.

There has to be a diminishing return on a heavy spring, right? Especially considering all local sites I run on are bumpy, at best. At worst, pavement breakage, big heaves, nasty pavement transitions. A 1000 may be wrong for those conditions, right?

SSM is going to be fast in TN! We have Dan Chadwick (2009 SSM National Champ), myself (2007 ES National Champ), Midtenn (Andrew Cowden, 2009 ASP trophy winner), Carter Thompson (Mulit time Pro Solo Champ) and his dad Jim (former National Champ) are in the process of building an FD for SSM too!

The FD's at Nats were all turbo but all different. Dan and I run a twin turbo 2 rotor, Andy McKee runs a single turbo 2 rotor, and Erik Strelnieks runs a single turbo 3 rotor. Erik has to add weight to his car to be legal, Andy is close to minimum, and Dan an I need to lose around 200 lbs over the winter.

Andrew is building turbo 1.8 but I don't know all the rest of the specifics of his build so I won't speculate.

Brian

Those are just different flavors of Torsen-type diffs, along with the Type-1.

I will disagree. We changed out the torsen in Dan's RX-7 for a Kaaz and made all the difference. Also, the torsen equiped CSP car I drove early in the year recently got an OS Giken and eliminated the wheel lift induced one wheel peel that you get with a torsen. Torsens will not lock in if a wheel is in the air, where a clutch diff is locked until a certain torque is applied to overcome the friction of the clutches.

+1

You guys are going to have fun with that car at class min!

I read the whole thread on the SCCA forum on the ultimate NA/NB ssm build. There was back and forth over SC vs turbo. Chris' is not the only SC ssm build I've seen. I like the buffered delivery of my small/mid size turbo setup. I feel it gives the rear end some hook time at the start, as well as corner exit, before launching the barrage. It is not good for balancing on throttle, and especially in a real transition environment like slalom, because of the stepped delivery. That is, if you use throttle to balance in a slalom, which I don't think you should need to (I am not a top driver, though). This opens up the can, right?

If it helps any I run 700f 450r on my Mr2 on Koni Sports non revalved. It's not bad at all on the street. It would be better with some race valved shocks in the front and if it had the motor in the front like the Miata.

Webby...why not valve the shocks for 650 springs to save time, effort and money later. They can handle springs 100lb/in in either direction which covers your 550s for now and your 750s for later.

I just got some HDs...and plan on doing the same eventually...but from 450-650ish.

FYI- I'm running Ohlins DFV custom 12k/8k, work great for autoX but can be harsh on the street.

CrisS- Thanks for the correction. I accidentally bumped up a page to SM when looking up the weights for SSM.

Beginning of this summer I was on track to come get beat by you guys out at TR. Was going to make an appearance for ETR, but my motor blew and I'm back quite a few steps.

I plan on running the 15x9 6uls with the 275s as well. Dave Disney got his to fit in his 99 fairly easy. He's car a pretty good example of a DD/autox SSM car. He trailers his hoo-hoo's in every event, runs an older FMII setup, probly around 220-230rwhp, Koni's with GC's. Probly the easiest/cheap way to get into SSM and be "quick".

East Tenn Region is pretty small (60 cars an event usually) but FTD is usually close between Disney, a BSP Z (really a BS Z with a diff :-\) and Gebbia. The ASP vettes have disappeared middle of this season :(. Was always fun to watch them run.

I was hoping to grab a consistant FTD in ETR with my car, or at least have my friend (driver of that BSP Z) put up FTD. But hey maybe I can get everything put together quick enough :laugh:

Hopefully I can come watch some of the SSM battles over at TR before I head off to AF :).

Mike, I'm not sure what kind of layouts Atlanta has but Chattanooga Region recently got the BIG auto auction parking lot. Suppose to be pretty fun, I'm planning on making a few of them in my dad's STS car. Would be cool to see you and your car run :).

12k=672#
8k=448#

Mine will be 550/350. Yours has a stiffer relative rear roll rate. Are you running rear bar? What front bar? How does yours behave in transition and in corner entry? Not too tail happy?

Doppel, with the Ohlins and the rest of your build, you have quality shit. It looks fantastic. Great pics, too. Your eye doesn't process junk. (PM pics of your woman)

Wheel rate is what really matters, and they will not be the same on your MR2 and the miata given the same spring rate, especially with the mr2's strut style suspension. So, the comparison can't really be made. (See motion ratio).

I fail at planning ahead. This is a reasonable idea. I may call Shaikh and see if he can adjust, but it's probably too late as I think they are going to ship next week.

It's not a matter necessarily of running out of gear. I have spent the last few years building and adjusting my car to mask my many deficiencies behind the wheel. At my current power levels, I tend to roll the throttle on too quickly and get some wheel spin on corner exit. Swapping to the 3.63 will not only give me a few more mph, but may help reduce the wheel spin on exit. The torque curve on my car is such that dropping the 300 rpm or so on any corner exit from 35 mph to 50 mph, I am still going to be in the 250 ft/lb area. I still have some tuning to do, and expect more power out of the motor. I need to get my knock sense dialed in, and possibly larger injectors. Once those things are in place, I think I have room for more timing, which is where the real power is.

I run the torsen diff in my car, but my spring rates are such that although I do transfer some weight off the inside tire, it is never enough to unlock the torsen. One idea I have been bouncing around in my head is to reduce the front caster to keep more weight on the inside rear wheel. I may play with that some in the off season but it really hasn't been an issue yet. You need a limited slip of some type. I haven't driven the OS Giken, but am tempted too. One benefit of the torsen over any of the clutch type diffs is maintenance. You don't have to adjust it and it will work the same until you break it. The down side is that you can't adjust it. It's a two edged sword.


My rates are probably at the upper edge of diminishing returns. I ran 750/400 last year and upped them to 1050/400 this year. Most of our lots are fairly smooth. On a rougher surface it might be too much. The old saying is "stiffer is faster, until it's not". I am not sure I am there yet but I think I am surely pretty close.


I have a picture somewhere of two stacks of 275s. One set on 10" wheels the other on 10.5". There is a noticeable difference in the height of the stacks. The 6ULs are great wheels, and a great value, but IMO they are not wide enough for 275s on a national level autocross car.

We get some good ones at Turner Field and Atlanta Motor Speedway. I've managed to get into 3rd geat (6spd/3.9diff) at most events. We've had fast courses that the front runners are in the mid-60's to some that were down to high 40's.

I wouldn't mind coming up to an event in Chat. and checking it out :) Well see how next year pans out.


BTW in my region, only 3.47 points seperate the SSM leader and 2nd place......and i'm in second place with one event to go...talk about "down to the wire".

Everything is in flux with the car right now. I recently put a 96 motor with a FMII kit (T28) in the car. I don't have an ECU, so besides starting and warming up in the driveway, I'm waiting to start actually driving the car and really starting to sort the car out. Here is the plan as I see it right now (just the basics, no details b/c they may change):

Motor and driveline:
- Hopefully next winter (2010) I'll swap to a 99+ motor, clean up the ports on the head, maybe some rods and pistons. Nothing special really. Just need something to reliably run about 8-8.5k (yes I know there isn't power up there, just saves that extra upshift on some courses)
- GT2560
- 300whp / 250ft*lb goal
- E85
- KAAZ 1.5way or OS Giken LSD w/ a 4.1 rear.

Suspension:
- Koni Race Dampers (short term until I can bite the bullet for double adjustables)
- 600/350 spring rates
- RB 1.125" hollow front sway bar
- tubular upper control arms
- Delrin bushing equiped lower control arms (tubular later)
- 15x9 ULs w/ 275/35R15's to start with. Eventually I'll go with 15x10's.

Interior:
- Standard CSP job. Remove the rest of the AC, soft top, radio, seat belts ect. I have to check on a proposed rule that allows me to just remove the passenger side air bag without having to do the whole dash swap.

Chris, you want a strong turbo setup, lag is my friend and can be your's, too. What about tc? I was speaking with a guy last weekend that tunes AEM, he says they have a tc setup that works without wheel sensors, just from what the computer expects engine acceleration to be.

Dude, with that forward biased roll couple, I don't doubt that you don't lift inside rear tire. I am going to look at all your videos tonight to see if I can see if you can discern push with that setup. How does that behave on turn-in and mid corner? Have you tested a heavier rear spring? I'm not arguing with your choice, I'm just curious.

+1 on the wheels. I just don't want to afford a setup like yours. Any thoughts on the compromise: 10" diamond racing steels at about 22#, or 9" 6UL at about 12#?

What injector do you plan on with that E85 setup? That's going to need a ton of fuel. You are around the same spot as I will be in next year, but I won't be stripping the interior parts or soft top, and I'm keeping the roll bar for track days. I'm at around 2240 right now without my fat self in there. PS and AC delete, driver airbag delete, 1/2 tank.

I'll probably end up with a 750cc or 800cc injector run E85.

We had our last autcross events of the season today and tomorrow. It was 25 degrees this morning with ice on the roads. No way was I taking the '94 with bald RA1's to the event.

I wound up taking the '01 with the dunlops. Still no traction with cold and rock hard tires. The high for the day was 36 degrees (normal is 61 degrees) and we froze our ass off. I'm not sure if I'm going tomorrow, I hate to bail on the last event of the season, but it would be nice to get some fall shit done and get ready for installing the roll bar in the '01 next weekend.

I am not going to get into the turbo vs super debate, but I think I will stick with the belt drive for now :2cents:

There is a rate of acceleration based traction control in the MS-I code and supposedly some beta MS-II code that has it as well. I will be trying it sometime in the early spring.
You aren't going to find any video with the 1050# fronts. I only put them on for one local event before Nationals this year and the only video I have from Nationals is one run in the wet on day two. The car will push when the front tires heat cycle out even with just the 750#s on front. But with fresh tires, it seems to work pretty well at least in the limited testing I have so far. I will keep you guys posted when things warm up enough to consider any results valid.
That's a power level / shock question. If you can control the heavier tire, wider is better, if you are on the edge of not enough power or shock, lighter is good.

I am on 750cc and 60 psi of fuel pressure and am getting close to the 80% range on race gas. I would think at least 1000cc for E-85 at national SSM power levels.

There is some easy weight to take off in the right place for next year. Being able to replace the pop-up headlights and all the associated hardware with fixed will take 20- 30 lbs off the nose with not a lot of effort and be pretty easy to restore if you decide to.

Here is an email conversation I had with Jeremy Schuster when I first started tossing around the idea of building a SSM Miata. Jeremy ran EM/SM2 for years before finally getting fed up with not having enough tire around 2005 (before the 275/35R15's A6's came out) and built the car for SPO (road racing). He's spent many years developing the car around undersized tires (245/16's and eventually ended up running 225/15's).

Chris, have you messed around at all with the anti-rev in MS? I may try it out at next spring's test and tune, but it seems a little limited and the cut comes in hard. Have you found anything online on it in any forums? I looked pretty hard yesterday, but didn't find much. I wanted to find some data and feedback from people who were using it.

On the wheel question, I will consult with Shaikh and my checkbook, and see what setup makes the most ultimate sense.

What fpr and fuel pump are you using? I may work these upgrades in during my winter downtime.



Midtenn, that is a ton of fantastic info from Jeremy Schuster! Thanks for sharing. That is unreal power he was getting out of these miata engines and the 2560, makes me feel like I have a setup that may be able to scale well.

Like everyone, I have a finite budget for this off-season build, and it will inevitably be a balance of compromises. My goal is to move up the pax and shoot for regional top times, and not looking like any more of a dork than I need to at the tour and div events. I'm going to give up some power for reliability and strength, and I'm going to STREET DRIVE the car and drive to events. Should be fun.

What are others doing in car prep during the off-season (if you have one!)?

Thank you. I like having a car that performs as well as it looks...it's quite the challenge.

I'm running a FM rear bar on the middle setting and a FM solid front on the soft setting...though i've thought about going hard to see what happens. The car is ver sharp and stable on entry but I was having trail-braking issues that hopefully my Brembos will take care of. As for transitions, I can get the car to do what I want with the throttle pretty easily. But remember, I did do a lot of competitive drifting for quite a number of years so I naturally like a tailhappy-ish setup....on-throttle rotation can be fun and impress the "old dogs" at some events :D

I wouldn't mind having someone else drive the car to evaluate it though...someone who knows the game well.

Poly bushings!

I am running a Walbro-255 in the tank and what used to be a rising rate fuel pressure regulator that was on the car when I bought it. If you don't connect the vacuum line, viola' it becomes just a fpr.

I have not been able to find much information on the MS traction control. It wasn't terribly popular in the MS-I which is why it didn't make it to MS-II originally. You may have found my thread on MSextra.com where I have been lobbying for its return.

My off season is hopefully pretty light this year. I am most likely going to upgrade to 1000cc injectors. If they appear to balance the EGTs I won't add the individual gauges to each cylinder. I am swapping out the popups for fixed headlights. I need to redo some mounts for the passenger side Kirkey seat and get the stocker out of there.

Then..... depending on what I think the total weight difference may be I might put in a cage and fuel cell. I am definitely going to run SSM another year. (I am glad to see more Miatas coming into the mix) After next season, the car is going to see some time trials, time attack and maybe some door to door track activity. That means I need the cage at some point. If I can do the cage/fuel cell and stay within 20 lbs of non caged weight I will do it this year. There is still more HP and torque hiding in the motor. If that number goes up to 350+ I will probably be okay taking the weight hit for cage :giggle:

They way I read the rules (somebody make sure I am not just reading what I want to hear) I can gut the doors and door panels to install nascar type bars on both sides. That will offset the weight somewhat. Then I just need to figure out a dash bar. I am thinking of making it a low hoop over the existing dash, so that if the windshield gets removed at some point for XP or track stuff I can just remove the dash under it. Any thoughts? I don't want to hijack this thread. If you want me to start a new cage one I can, or since it is sort of a SSM debate, weight versus stiffness maybe it should stay here.

Chris, not a thread hijack at all, so don't sweat it. Obviously for the most part you will be building the cage for the wtw racing ruleset; what class/sanctioning body would you be looking at? If you don't have your own source of info for it, I can get in touch with a guy I know that builds and races SMs and get his total cage weight and tubing specs, and what weight he saved/gained from gutting the doors to add the nascar bars. I think quantifying the additional stiffness from cage installation may be difficult, but I'm sure it is substantial.

Double post, see below.

The more data the better. If you don't mind asking the weight question I would appreciate it.

I am looking at the SCCA GCR rule set, but a supercharged Miata really doesn't have a "good" place to play. ITE-U is kind of the catch all. Part of my issue is the front hoop. If I leave the windshield, the continuous hoop "should" follow the windshield header. I am betting I remove it in a couple of years so I want a lower front hoop.

Patience may be the key. Trying to keep the car SSM legal limits me. IF I were going the full XP route, I could take a lot of stuff out of the way and do things differently.

I have been in a few Spec Miatas and didn't like the cage placement near the drivers foot. I am still trying to figure out if there is a way to have the front hoop terminate at a spot on the floor, so that I can use it as the dead pedal and not have it against my ankle.

In a perfect world, I would have a cage that is a) SAFE, b)SSM legal, c) XP legal, d) functional with or without a windshield and dash and e) legal for SCCA ITE-U, NASA, Redline Time Attack, and Formula the D word we don't use around here again with or without a windshield.

I am just starting to toy with the idea, so I really haven't done enough of the research to know if all those goals are attainable.

I agree that the chassis will be noticeably stiffer but, back to the SSM content, will that increased rigidity offset the weight penalty? It would be great to know how much the CG of a Spec Miata goes up with the installation of a cage.

The setup will have to change a little as some of the chassis flex that used to dampen body roll and wheel inputs will be gone.

When I talk to my contact, I will update. He said he prefers to buy a 'seasoned' tub for some of that flex you mention above.

About the windshield header bar being lower than the windshield header itself, do guys building XP cars do this? It seems that, especially in a track situation, you will have helmet broomstick clearance issues by putting the front of the halo any lower than maximum possible height.

About the front hoop to floor, I know the autopower off the shelf kits have that bar in front of the dash, in a terrible location wrt driver's leg. Take a look at this from miatacage.com: http://www.miatacage.com/images/lowe...c562d477f98e3f
This looks like instead of acting like a dead pedal, this cage clears your leg well and won't obstruct a real dead pedal. Their cage has a bar behind the dash, I have no idea if that's SSM legal, but it should be SCCA/NASA, XP, RTA, and FD legal, I would think. I will try to get a pic of my contact's SM cage wrt down bars, too.

Getting back to your car, reading your post in the brake thread made me think to look at your brake setup. Have you ever thought of going to a bbk, specifically with a two piece rotor/hat, like what Emilio is selling now. He quotes a 12# total weight reduction over stock, of course unsprung. I am not adding lightness at this point in my build, but this combined with a tubular suspension arm (so do we have to follow the SP one arm per corner rule 15.2.E?), could really reduce unsprung heft for you guys at the top end.

One more thing for everyone, what kind of chassis bracing are you using? I have frame rails, which are a no-no and will be removed in the off season. I will miss them, as they WORK. Something as simple as the 949 front and rear sfc's? The triangular beatrush is illegal, I think, because it connects the rear subframe and ppf together, right?

A true "XP" build would only have a roll bar not a cage. Look at DP. The broom stick has to clear the helmet from the front hoop to the rear hoop. You can adjust the height of the rear hoop if needed. It may look a little funny with the windshield still attached, but it only stays on for SSM.

The dash bar should be legal, but with a low front hoop it may not be necessary. Running the braces through the dash/firewall forward may be more difficult with the dash still intact.
I have considered it. Just haven't done it yet. I would be afraid that it will push the bias back forward. It will probably happen before the first non time attack type track event.
Correct on all assumptions. I am just using the stock lower braces and calling that good enough for now.

Guys, the thread on the other boad, 'So SSM now...', got me thinking about what a money no object(ish) SSM Miata build would look like. Do you think an NB is intrinsically better wrt a bit of a larger tire fitting? How much of a problem is getting heat in the tires for you? What about a bit of a heavier car to fit the min weights with a bigger tire, to heat the tires better?

I know a real money no object deal would be some sort of 4 rotor or rotary with turbo monster, but what about with a miata engine? Midtenn, if you're still out there, in your convo with Jeremy Schuster, he kind of glossed over 'intake' in his email. Any idea what was there? Looking at high-powered build on this board, the intake MAY be the limiting factor in making huge power in this engine.

My thought is 1.9, 99 head, ported at the flow bench, cams selected and degreed on the dyno, custom intake, ~2860RS or a serious s/c like what Chris has) on a shortie, short charge pipes (a la the tube front drifter on this board), v-mount ic, maybe water inj (I don't think meth is allowed per the rules?), tune optimized for race gas. CSP style flywheel/dual plate clutch (high idle, anyone). Maybe we could source a sequential gearbox so that the engine could be a little peakier than normal.

ECU, something with high resolution tables and a VSS based real traction control. AEM, adaptronic?

Suspension, similar to what Chris has, with custom made chassis bracing. Maybe have a second set of dampers and springs, heavy/light setup depending on site quality: 800/~475, 1200/~650. Largest tires avail/practical as per 1st paragraph.

Brakes, try to source a small 2 piece rotor and lightweight alum caliper.

Add in what you think. Have fun.

There was a pretty long thread on SCCAForums.com about a year ago on this subject. SCCAForums.com - SM2 NA/NB Miata Build

Jeremy ran an ITB setup with a custom plenum.

I have to disagree with starting with a NB chassis. If you're running SSM seriously, just be prepared to cut the fenders and bolts on some flares. the NA chassis is inherently lighter to begin with, so starting with a 90-93 and doing a 99+ swap is your best best.

I read this a while ago, and read it again today after your post. I was kind of thinking of taking that further. Example, in that thread it was said TC, but not how to implement, assumed 275 was the tire of choice, assumed that the GT28 was the turbo, etc.

FYI, I messed around with rev control in my MS1 the other day at my shop. Just to get it so it wouldn't cut power in first gear in a controlled roll-out, you would probably have to set it to cut at ~4000 rpm/sec or more. The question is if this threshold is enough to do anything in second gear. Effectively, without having vehicle speed sensors, a way to switch it on/off once you are in second, or have it know what gear you are in, you will have to basically give up acceleration in first gear in order for it to do something in second. Again, this is without doing much work, or even reading much on how the system works, so I could be off base.

Anyway, I posted this after thinking about what was going on in the thread on the other board re SSM. I find it hard to fathom why an SSM car wouldn't have a CSP car beat on the autocross course. The assumption would be that the extra power with fi in the SSM car ruins the car's balance because of weight or power delivery. Is this really the case? If that's so, could it be possible that I am better off with my little 1.6 making 220 than a much more radically tuned 1.8 bored to make ~300? Would a well-prepared CSP car with a well done fi system be a class-killer in SSM? Would a maxed out n/a engine be better, as is being discussed on the other board? 1.8 stroked to 2.0, high comp, cams, ecu with a radical tune and a huge redline?

Further, what about Bill S's question about running a bigger tire on the car? It doesn't seem that there are any tires wider than the 275 with a diameter equal to or smaller than it. And Chris, you said that you contact your bump stops at the same time as your tire hits the top part of the inner fender? Is this in the front or rear?

I have my set of 275's in the basement, wheels will be on order within a week. The '90 will get a 1.8 engine transplant, new exhaust for my GT2560R, then it will go to the body shop for whatever it takes to fit those 275's under the fenders. If it's roll and pull, so be it. If it's flare, so be it. The question is, will it fit a bigger tire than the 275, and will it benefit from a bigger tire and the additional weight per the weight rules for the class?

And, in the end, can it beat the RX-7s in the class?

It is yet to be seen. The 3 top RX7's in the class have years of development behind them (with Dan Chadwick's have even more improvements to be made). I basically plan on nearly cloning Jeremy Schuster's car as a starting point (with many of his "old" parts actually, haha) and he was definitely competitive back when he ran Solo.

Well yesterday finished up the season for me. I got second (a whopping 1.064 behind first). I secured 2nd in SSM for the year out of 23. Got 22nd fastest time out of 150 people.

I need that fuggin OSG diff.

I was talking about the rear.

You can't put a bigger tire in the rear at any reasonable ride height without having essentially a 0" back space, because you can't alter the tub inside the hub face.

I really hope the answer to the last question is YES. I have spent a couple of years trying to prove it but haven't had much success yet. The goal for next year is minimal changes, lots of free wine courtesy of Bill, and having something to keep the rx-7s thinking about.