Super Touring Light Miata (SCCA STL Class)
 

I’m toying with the idea of building an SCCA STL class car for season after next.

Here are the highlights of the class:
Weight with driver 2399 Updating and backdating between years is legal
Brakes - must use stock brakes
ABS – only from the car it was designed for.
Engine (N/A only)
11:1 Maximum Compression
No head porting
.425 maximum lift cams

Suspension – stock pickup points, shocks, swaybars, etc… are open
Wheels – 15 x 7 maximum
Tires are open
Differential is open as is rear end gearing

Thoughts:
Start with a 2002 chassis, Make sure it has sport brakes, 6 speed and ABS. I’m a fairly big fan of ABS – Is the 2002+ ABS that much better than the 1999-2001? I know a lot aren't. If I started with a 1999 chassis, it would be much cheaper to build it.
How easy would be to put a 1999 motor in a 2002 chassis?
Add an OS Giken differential, and play with gearing a bit, I’m thinking of starting with 4:3 and going from there.
Xida coilovers, ISC spherical bearings, etc...
Small 2” splitter by the rules and very small rear wing by the rules.
Engine I think should be a 1999-2001 with big cams, bored to 1849CC, flattop intake, COP, dry sump. Rebello believes they could get this to 225-235 hp – keep it under 8500 RPM to be reliable. They have several cam profiles for .425 lift
I’ve thought about the 2002+ motors, but not sure of all the differences, and also not sure the extra midrange torque would be helpful as the car would most likely spend almost no time under 5000 RPM.

Really looking for thoughts between the 1999 and 2002 chassis and engine combinations?

I've not kept up with SCCA rules in a few years, but wouldn't the update/backdate rule allow you to start with a 99 chassis then swap to sport brakes/02+ ABS/VVT motor/etc.?

I plan to run STL next year. In fact, just ordered some suspension today. :)
Looks like it will be more fun than ITS. Last I looked at rules, brakes were open. I've seen them with wilwoods.

I've also been told that the hot setup will be a 99 head with big cams. Apparently they can get better power up top on the 99 head due to better cam selection. There are interference concerns with the VVT head. The VVT head has been shown to make more torque down low, but you shouldn't be under 4-5k rpm at any point anyway.

IMO, 225-235 is very optimistic. That would have to be crank hp, and even then on a very friendly dyno.

Thats what it sounds like to me.

225 whp seems pretty optimistic for N/A 1.8. Even at 8.5k rpm.

I agree with Track, it would be extremely impressive to top the 200 number N/A. Emilios motor in crusher was severely built, and I think he was around 150 hp, though that was limited by his class. Also, miata2fast has a heavily built motor running itb's, and I don't think he's close to 200 either. I'm not 100% sure on any of the numbers I said, so don't hold me to it. Hopefully those two chime in on your build.

Good luck, car will be sick no matter what.

225whp n/a on stock ports isn't optimistic - it's impossible.

225-235bhp is ~190whp, which is probably doable with enough cam and revs.

yea, sorry whp is habit, thats why I said its a bit optimistic (in otherwords, I didn't mean to put the 'w' in).

Either way, I have still yet to see a dyno for more than ~180whp. Either way, go for it! I am not trying to discourage, just warn that the hp figure seemed a bit optimistic. Then again, those dynos probably didn't have the funding this would have.

It was 225-235 at the motor - Sorry for any confusion. I'm thinking 180-190 at the wheels. My motor now with 10:1 and a ported head is at 208hp on an engine dyno with a set of Integral stage 3 cams, no drysump. I think the drysump would add 5-6 hp, bigger cams should add a bit, 1 point more compression, but no ported head. Might be slightly optimistic, but maybe not. I know the FP/EP motors are pretty close to that.

The brakes are not allowed in STL. I have a set of the rules here. They are allowed in STU though.

G. Brakes
1. OEM brake systems must be used. Alternate OEM brakes rotors or
calipers from the same manufacturer will be considered.

I can't image trying to swap the ABS to an earlier car. Actually I can image it, but it would not be fun. I've put a Honda S2000 ABS system into a Mazda RX7, so I know I could, but I would rather buy the 2002 and swap the engine I think?

190whp and 2400lbs and they don't allow big brakes? Looks like they want a repeat of the T1 vette fiasco.

I think I noticed a difference betwen the 03 I had and my 99, but it might just be the EBD in the 03, I seem to be unable to dial in enough rear bias on the 99 (even with rear sport rotors).

There is a lot of FUD around VVT, especially in High comp, big Cam theoretical setups. It's not rocket science, it's just not that many to copy :)

Is the inteference (cam lobe to lifter pocket)less of a problem in the 99 head?
Or is the "interference issue" around the valve-piston clearance at max advance (which might be visited by mistake with poor VVT control).

Same manufacturer... wonder if you could get away with running some RX7 calipers or something? I've seen two Miatas now with them, both track cars. They built that set up long ago though, before there were willwood kits around.

We have built a STL Miata ran 2 events last year working out some bugs. Had a minor problem with a rod bearing and have the engine back out now. Going back together soon with different cams and should be even better.
We are going at this a little different than most are, we are running a 1.6 at 2132lbs

Your build sheet looks good except:
Flat top manifold isnt legal - Must be USDM part
Dry Sump Isnt legal

Just a couple things to look at before you spend money on stuff you cant have. Good luck with it and hope to see you at the track!

Here is a pic of our car, minus the aero parts in this pic...
https://www.miataturbo.net/attachmen...ine=1325515987

I get lot of customers ordering parts and getting set up advice for STL and STU cars these days. It seem there is a bit of money to be had if you do well.

Can someone with knowledge of the SCCA ST scene break down what contingencies/prize money is available and from whom?

I'm not crazy about the engine rules and 8" wheel max myself but it is a interesting engineering challenge going up against cars with a bunch more power.

From what I've read on the miata net the 01 come with bigger brake optional package which pre 00 do not have. Also o1 motors have the vvt...don't know if you'll keep that but that's an option. I don't know if there's any other performance changes between the nba/nbb models.

STL is a regional only class, so there are almost zero contingencies/prize money to speak of (as far as I know).

STU is a national class, it should have contingencies similar to other national classes. That is, Mazdaspeed contingincies of up to $500 for a win (if 4 starters). Also, Mazdaspeed pays $1000 for a division championship, up to $1200 for a June Sprints win. Hoosier, BFG, and Goodyear all have tire contingincies. Hoosiers is 2 free tires for a win (min. 3 starters in class), BFG gives 3 free tires for a win (min. 3 starters in class). Goodyear is 2 free tires for a win (min. 3 starters in class). Hawk and Cobalt also have a brake pad contingency of 1 axle set of pads for a win. Carbotech usually has a contingency program but it hasn't been listed.

So all in all for a National win with four starters (might be possible in STL/STU) you would get $500 cash, 2-3 free tires and a set of front or rear pads.

As I was writing this, I checked the SCCA website and it looks like for this year and onward STL is a national class. So all of the contingencies I listed for STU will apply. However, STL will run with STU at the runoffs, so no STL car would have a chance at the Runoffs... An STL car (or STU for that matter) running at a "Regional" race will not qualify for any of these contingencies, only at "National" races.

BTW entry fees for National races are on the order of $350 for a single and $500 for a double. So the entry fee will suck up most of the cash winnings from Mazdaspeed.

The lifter pocket is the same between the 99 head and the vvt head IIRC. It is not that big a deal to modify the lifter hole for the camshaft to clear however.

I would think that interference of valve and piston on a vvt motor would be an easy problem to solve. What might not be so easy is to keep the vvt working properly and from breaking other parts at such a high rpm.

If you have your heart set on running in the SCCA why not run in a prod class? There is no contingency money available in regional racing or tire contingency for that matter. At the national level, running up front can help offset cost of entry fees and tires.

As far as hp, 180 whp seems to be good for a 1.8 ep car, 150 is big for a limited prep f car. My car dynoed at 154 and 112#, with intergal 4 cams, 10:1 Pistons and the allowed porting and crank work. Tuned on 100 octane race gas.

Now I see the above post showing STU will be a national class.:facepalm: Plan on spending some bucks for an engine with nationally competitive power.

Our first STL Engine made 150whp and 120wtq and was limited to 7500rpm, it was a 1.6L

New engine is almost ready to go in...

On a 1.6 I would think 150-165 is possible, but difficult without the 99 head.

STU is going to be tough. A friend of mine is building an S2000 with about 300 Crank HP and revs to 10K RPM. To be competitive you would need boost, and even then I'm not sure.

STL is a national class as well, and with the limits the Miata should do fairly well. Weight is a concern of course at 2400lbs for a 1.8. EDENS approach to use a 1.6 at 2132 might be faster, hard to know. Easier for sure.

What are the rules for head porting in the class? Im guessing the wtq number is d/t compression ratio.

Porting on the head is limited to port matching only, to 1 inch in. Compression was 10.8:1 on that engine.

You do know that a turbo miata finished second in STU at the runoffs this year right?

I think an S2000 would be a good STU car but it would be an expensive build. That and even a 300hp S2000 will probably have trouble competing with the A4 that won this year.

Any lower powered car will always have a hard time competing at Runoffs, for obvious reasons.

Fixed that for you. If the runoffs return to a place like Mid-Ohio it will no longer be a horsepower race...


Wait....was that the obvious reason...

Yes. ;)

Yes, I'm aware :) , but it's a new class and cars will continue to get more developed and faster. Maybe a turbo Miata can compete, but it will get harder each year for the next couple as bigger budgets / better developed cars get involved in the class. STU is going to be a very expensive class.

Bigger budgets? Lol, the last two STU national champs were running $80,000 ex-world challenge cars.

My understanding is the SCCA want's to get away from that but yes, I agree, STU is going to be a very expensive class. That's why we're not building any STU cars from our 3 T3 S2000s. The car we ran at the 25hr at Thunderhill did finish 5th in STU at the runoffs...

Really old thread

BUT

SCCA just released new rules for next year and there are quite a lot of changes for STL.

RWD penalty increases to 5.5%, so a 1.8 miata has to run at 2635 lbs. EEP

FWD 2 liter strut cars (ie 2006 Civic Si) run at 2633 lbs.

Anyone have experience racing a miata at 2600lbs......?

They also added restrictors to the RX8 and the Honda K20 motor. 45mm for the RX8, 50mm for the K20.

Emilio asked earlier about contingencies and these have also been changed since this post first started. In 2013 Mazdaspeed paid $800 for a Majors win in STL, and usually there are two races in a Majors weekend. So, in a competitive STL miata (there's a few around the country) you could be looking at $1600+ in a race weekend (+ equals tires, brake pads, Summit contingency, etc.)


I was thinking building an STL miata could be pretty fun and not too crazy expensive (at least on a regionally competitive level) but I don't know now that they've up'd the weight to over 2600lbs. That just seems crazy for a miata...

I was looking at this recently. The contingencies attract me just like everyone else contemplating an STL Miata. Engine won't be cheap. It will need every bit of power it can get against 250whp Hondas that weigh a lot less. Cam design would be critical as that's where all the power is with these rules. There is enough freedom in the engine rules to warrant maybe $10k worth of power making hardware alone. $4000 diff set up, etc.
I think the max a legal STL Miata can make is around 185whp on 100 Sunoco. That will get its ass kicked on power courses like ACS, PIR,MRLS but might be enough on handling courses like BRP, TRP, Sonoma, et al

The ROI is potentially better with an STL Miata than just about any other class a Miata can run in except SM. For me, the ROI isn't worth racing a car that intrinsically I just don't want to drive. I'm too much of a car/driving geek, wanting to race a car only if it feels a certain way. No aero, skinny wheels, heavy as an S2000 (ugh). I raced NASA PT for three years and that was a $$$ black hole, even winning a lot. Fields too small unless you run Spec Miata though.

It hope somebody figures it out and win runoffs in an STL Miata. Of course that would earn a bigger weight penalty..

Which Hondas have 250whp? The car I drove to 4th at the runoffs this year dyno'd 210whp (on a calibrated Dynapack). Chad Gilsinger's car (finished 2nd, ahead of Jim Drago in the highest finishing miata) made 207whp on the same Dynapack.

Both of those cars have bone stock engines internally, except for the cam (which is a stock cam ground down to meet the 0.425" lift).

John Schmitt had the highest whp Honda in the race, and his car dyno'd 224whp also on a Dynapack. John's motor was built more to the limit of the rules, but not 100%.

Regardless, unless we're talking about Church's dyno, no one was running 250whp in STL, and I seriously doubt you could make 250whp within the STL ruleset (unless you're running an RX-8). Especially, now with the 50mm restrictor. I'm guessing the car I ran will make under 200whp after the restrictor.

Also the K20 powered Hondas weigh 2633 lbs in strut form, and 2700lbs in double wishbone form. So which 250whp Hondas weighed a lot less than a miata would? The B16 or B18 Hondas would weigh significantly less, but none of those cars were very competitive this year, and none of them made as much whp as the K20 powered cars. My car weighed 2680lbs at the end of the Runoffs race, I couldn't even get close to the min weight...

I have almost zero experience with N/A miatas so I would defer to your experience.

Supposedly Drago's miata made 190-200whp. I talked with him during tech, but I never asked exactly what he made, nor did I really check out his car. I believe it's a '99 motor with a BP4W head. I don't think he's running a VVT motor but I might be wrong.

I was never around Drago on the track after I got taken out in T1 on the 2nd lap, but based on the straightline speed of Dragos car compared to Chad's civic, I would guess the 190whp is a safe bet.

From my Grand AM experience MRLS is not a horsepower track, and I think the ST results from the last few years show that. MX5s have dominated at that track, the high hp, high tq cars in the class weren't even close. That said, I think a miata would have a decent chance at the 2014 Runoffs at MRLS. That is if no one shows up in a well sorted RX8.

ROI and racing probably don't belong in the same paragraph...

My feeling on the whole driving a "shitty" race car is this: I'd rather drive a bad race car against a lot of competition, then drive the most fun, most balanced car at an HPDE or TT. Competition against a lot of cars is where it's at, and usually that means driving a car you don't get to chose the rule-set for. STL had the third highest car count in all SCCA racing last year, behind only Spec Miata and Spec Racer Ford. To me, STL is much, much more appealing than those other two classes.

Honestly, in most of the Grand AM races I did last year, our car did not feel great. Driving FWD cars, set up to kill you, on the hairy edge isn't exactly fun, but the competition is amazing so it makes it worthwhile.

I think following your own formula (well, a much cheaper formula than maybe you usually use) you could build a fairly competitive STL car for not too much money. It wouldn't be fast enough to win the runoffs, but it would be fast enough to win at most of the Majors races. Mostly because the Majors races are people just double dipping their SM cars, and other people running not super competitive cars. I think someone with a 165whp, 2600lb miata, well sorted and with some decent aero could do okay in the Northern and Eastern Majors tours.

Just guessing on Honda K20 outputs based on my limited experience hanging the guys at Jackson Racing and Skunk2. I'll defer to your expertise there.

ROI. Yah, it's dumb. I didn't say it made sense but you have to factor in cost if you are paying all expenses yourself. It sounds like you buy some seats and are given others for free. Mostly not racing your car so the $30-100k it takes to build and show up at the track isn't always prime consideration. You and I are different animals. I tinker, develop parts and tuning knowledge that many others benefit from. So what I drive matters. To some extent, you're a bit of a hired gun. Thus, you tend to just hop in and do the best you can. I try to make the car I already like competitive. I know it makes no sense to you and probably sounds stupid. Makes perfect sense to me and a few thousand of my friends and customers around the world.

You have made a few sideways remarks about someone with my driving experience racing in classes with little or no competition. I don't like it either but I have even less interest in driving a car I don't enjoy driving (that also costs a bunch to build) in a huge field of competitive drivers. I don't think you should bother trying to "get it". I'm not dumb, or afraid of competition, I just drive for different reasons than you do.

[QUOTE=hingstonwm;815644]

As far as hp, 180 whp seems to be good for a 1.8 ep car, 150 is big for a limited prep f car. My car dynoed at 154 and 112#, with intergal 4 cams, 10:1 Pistons and the allowed porting and crank work. Tuned on 100 octane race gas./QUOTE]

What's the word on Integral Cams? I got my Stage 4 back in 2005, but then I was told they closed shop. Then reopened in new state. Is the product still the same? My Stage 4 were hyraulic, as solids were not legal then. Are your cams set up for the solid lifters?

I am building a new engine for my FP, but will use solids this time. Don't know which cams to use at this point.

??My quotes don't come out in the nice box everyone else gets? My computer or what?

No, you cut off the ending [ \QUOTE] (without space)

Thanks!

I've never paid for any of the seats I've had, at least not with money. I suppose I have paid with the thousands of hours of volunteer time after hours building, prepping, developing, repairing, and maintaining the teams race cars. But, no, I've never raced (wheel to wheel at least) a car I personally owned.

This is an old article but it describes one of the teams I drive for and how it works ---> The Breakfast Club It Ain’t - Column - Car Reviews - Car and Driver

I wish I had the money to pay for seats but unfornately, despite all of the amazing benefits I have at my job, a large salary is not one of them. Nor even an average one... :cry:

I don't plan on staying in the lap of luxury forever, and one day I'll likely be building my own race car, and STL is one of the classes I would strongly consider. Hence, the bench racing going on now, in December, as it snows...



What in the STL rule-set turns you off the most? You make it sound like an STL miata would be atrocious to drive, painful even. My interpretation is that an STL miata would be very, very similar to one of your PT builds. The only big differences would be the 7" wide wheels, and the extra weight.

Obviously the engine rules are quite different, but at least in STL you wouldn't be trying to tune out 30 or 40whp. Like you mentioned above, how you make power in an STL motor will be quite different than how you've generally done it in PT, ie lots of cam and decent compression (as opposed to stock cams, CNC head, O/S valves, etc. etc.). So the engine rules pose a different engineering challenge than PT engine rules, but I don't think an STL engine would take away from the "fun-to-drive" factor.

Would 7" wide wheels and a couple hundred pounds of weight change one of your amazing PT cars into a undriveable turd? I'm not trying to be cheeky, honest question.

I was worried about the 7" wheels on the Civics, as well as the brakes. The 290mm max brake rule means we have to run smaller than stock brakes on our cars. We're not even maxed out on the brakes, we're running 282mm rotors with a two piston Honda caliper. If we had money to spend we'd have some 4-pot racing caliper on a custom 290mm two-piece rotor. Suprisingly the brakes worked fine, and the car handled pretty well with 7" wide wheels. Honestly, the STL Civic was more fun to drive than our Grand AM cars, and it ran basically the same lap times (only because of tires, BFG R1-S vs. Conti spec tire is probably 3s...).

Talking with Drago, I didn't get the impression that his car is "un-fun" to drive, but he did say that he ran the tires off his car. I don't know if that was his driving / poor set-up, or if it's something that can happen on a 2500lb+ miata.

Sorry, lots of blabbing...

P.S. Are you going to Thunderhill? I saw that only one 949 car was entered in E3, are you driving? Unfortunately, I will not be attending this year. I figured I'd enjoy a snowy weeking in Ohio more....

I simply said that I don't like driving certain types of cars that others (like yourself) find enjoyable. You should let it go. You're trying to understand or rationalize my feelings with what you feel. You can't. I simply do not enjoy driving some cars. That's it.

So you're being given some seats for sweat equity earned, no significant cash outlay. That was my point. Every cent spent to get the cars I drive to the start line comes out of the marketing budget of my tiny company (my pocket). Thus, I weigh the potential branding affect and fun factor against dollars spent. I'd run Spec Miata before and STL build I think. But nothing is set in stone. The engineering challenge of working within the archaic SCCA Super Touring rule set has some appeal to this car geek. If an opportunity presents itself, I may eat my words. I can understand your enthusiasm for the class given that your personal cash outlay could be far less than mine and the cars sounds like fun to you.

FWIW, I have driven at least one fairly well set up 2600# Miata with some power. I didn't enjoy it :)

My team is in the black #05 Miata in E3 at this years T25. I'm sitting this one out. Instead providing logistical support, equipment, tuning, conferring on strategy, etc. Wish I could be there.

[QUOTE=Team DNR;1080109]Megacycle allegedly has been making integral cams, but I have not worked with them. It may be worth a call to jesse prather if your looking for cams, he can point you in the right direction.

I did a lot of work / tuning with the integral fp4/5 setup. You really need to sit down on with a set of dial indicators and a dyno to make them work - cam timing is super critical to hit the sweet spot.

[QUOTE=mrjones2;1080258]Gotcha on the setup - like I said, we only used the cams for one race. I built the engine and dialed in the cams per instruction. Had a low redline for practice and qualifying to break in the motor as this was an absolute last second deal. Set it at 8K for the race. SOB took off like a Saturn V. This was at our SEDiv SIC in 2005. Actually a hoot to go from 7th on the grid to a win. Back in 05 the Integral Stage 4 were a secret weapon, I had like the third set ever made. Today, they are old hat.

Surprised to hear that Prather used hydraulic cams for Bill's FP. Maybe it is about the zero lash on a hydraulic vs the 0.10 or so lash on the solids making a difference?

Heck, it doesn't matter at all as long I can't get my dang MS3 to fire the car up.