SCCA Solo Street Modified (SM) Discussion
 

Ok, so there are now some Street Modified (SM) twins. Let's start a thread discussing where we have gone and where we can go in the class.

Here's my car. Who else is running SM?

@FRSport.com vs @whataboutbob:

http://sololive.scca.com/SM.html

-alex

Was discussing this with Tim White at Dixie...what a bad discussion to have for your future wallet.

I approve of this post. :thumbup:

Kind of rough giving up 0.4+ per side to the boost buggies. Looks like a fun car, keep at it!

The boost buggies are not the sm "overdog".

i have enjoyed the battles that @whataboutbob and i have had so far this year

our local SM champ, who also took 6th at the US national's this year, runs a 400hp+ GC Impreza on 305 hoosiers and probably on an STi drivetrain.

I can't even imagine prepping the FRS to that sort of beast-mode level without dropping serious coin.

How do you guys do it??!

This is pretty much what I have seen, plus mild aero.
Way mild as far as SM is concerned, too soon to tell if nationally competitive.

If you want a nationally competitive autocross class car, SM is a tough place to play and still be a daily driver, IMO. For that you still have CS or STX, though. As Bob has proven, STX+ builds can be very competitive locally, though and look like a lot of fun!!

If you want a Nationals jacket in the $pend Money class there are other power options vs the stock motor...full built EJ25, 2JZ, 4AG etc...

Way more power/torque to be had out there. In SM you can choose any engine/trans from the manufacturer. Being a joint venture build, the twins can get both subie and toyota powerplants :happyanim:, so a lot of options out there!

i definitely agree on a nationals style course that there is a level playing field between the RWD and AWD

there is definitely an advantage off the line for the AWD in the ProSolo series, but it could be course dependent on how much the RWD can chase them down.

I have a pretty well prepped STX car but I do plan on going to SM eventually, maybe next year.

It takes money and some engineering know-how. I had a 2.5L WRX I built back in 2004 and raced in SM and later put all of it into a 98 RS Coupe body.

There is a SM BRZ thread on NASIOC I've kind of kept updated over time and I did mention your car in that one after the Tour results.

I have one of the TRD superchargers which was produced, and should be good for roughly 400WHP on E85 with the right pulley. The Harrop S/C coming out is basically the same thing, TVS1320. I have a set of built heads I picked up for a good price and should be able to rev to 8500RPM without too many issues. I'm lacking a built block right now but will keep the 12.5:1 CR. I want to keep my stock engine intact, so I'm basically building a second engine. I decided to go S/C rather than turbo but I believe you could use either. An EFR setup with a 6257/6758 would likely work well.

How light have you guys gotten your cars? My old WRX and the GC I built after it had pretty much everything stripped out of it to the limit of the rules. A/C, all radio stuff, seat belts, etc. I'm not ready to do that with my BRZ. :) I have seats leftover from my old build but they aren't tremendously lighter than the stock seats and certainly much less comfortable.

Double post.

our car is currently in the lower 2600 ish range depending on fuel load.

My old GC was around 2690 with a 6 speed transmission, my 2002 WRX was 2830. I was thinking you could get the twins in the high 2400s or low 2500s fully prepped. Once you add things like aero, big wheels/tires, and FI it starts to get a little more difficult though.

I do expect it to be an extremely popular car in the future for SM though along with the RX8. Not sure why no one has built an RX8 yet since you can pick them up for dirt cheap now.

well minimum weight w/ forced induction is 2480 so we aren't that far off the pace right now. granted we still have aero to add to the car.

there is definitely some more weight to be dropped out of the car

Red v Red:

https://fbcdn-sphotos-g-a.akamaihd.n...30341123_o.jpg
https://scontent.xx.fbcdn.net/hphoto...23998910_o.jpg

Fender flares allowed? Imo you guys are going to need a 315 on all 4 and about 400 to the wheels. My bank called as I typed this and told me I'm locked out as a precaution.

You need power and grip IMO. I've done quite a bit of suspension work and added aero, the car is really panted at the moment. I also recently went to a 69mm pulley and the Delicious E85FF kit which is definitely helping. In the Pro Solo competitions it is really hard to keep up with AWD on the launch. I'm also in an auto so my launches aren't all that spectacular anyway. One day I'll have a Hollenger sequential and a Motec 150 ECU to solve that problem.

2775ish, not much weight reduction.

This is a shot from the 2015 SD tour, I'm about to shift from 2nd to 3rd. The RS-R CR coilovers are doing good work here keeping the car planted.

My god you would've done pretty darn good with a manual transmission and some weight reduction.

With you running in SM, with the stickier tires and all, have you changed your sway bars from what you were running in STX? Just curious.


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No, just the settings. I have changed the coils to the RS-R Club Racers.

I'm still running STX, with Tein SRC coils. Love them. Initially I went with the recommended stock rear bar and a 20 mm front bar. I found just a bit too much under steer for MY liking. So I put the 18mm rear bar back on. Now on slower course's it feels neutral and on the higher speed I had a touch of oversteer.
I liked it better this way. Still teaching myself this suspension magic. If I get time I will put full stock back on just to compare.
I can't see myself going to SM, way to many mods for a DD. Into SP is where I will end up. Intake stuff, E85FF. But then again ANY trany mods, valve body, clutch packs etc. is a straight SM move. 4.56 gears or higher could get you better launches.
BUT say never and that's where you up.


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What size wheels & tires are you all able to fit on the car?

As has been said, I think the magic numbers are 315 and 400. I like to use Panda as the standard for the direction the FRZ's should be going. Gotta fit the 315's and need at least 400whp. Of course the 315's will require someone to be willing to do some cutting and the reliable 400whp will likely require some decent engine work. Oh yeah, and axles. Gotta have axles.

I have a lot of evil thoughts that have been going on in my head as well. Aaron Shoe in his SM Evo is a really good friend of mine and we've discussed how to do it. I've seen the work that goes into that car (which can win Nationals) and it's not cheap. A lot of custom work and working through issues constantly. It's not cheap to run at the front, although Panda might be the exception. It helps to have a co-driver who is as dedicated to the build as the car owner and willing to put in a good chunk of funds to offset costs. And sponsors.

I'm at 275/35 and an estimated 300WHP on a dynojet. I haven't dynoed the car since the smaller pulley and the Delicious FF kit. I also have 450cc injectors that need to go onto the car.

I've posted a bunch of stuff in the BRZ SM thread Steve Garnjobst started on NASIOC awhile ago.

I think the newer group of TVS1320 superchargers coming out will be able to do 400WHP with a very good torque curve on E85. I have one of the original TRD superchargers using the same blower. KSR was able to get a little over 350WHP out of it running on 98 octane on a 9.5:1 CR engine. They built the car for road racing and had to use that fuel in the series. It's not going to be a torque monster but will still be good for ~300ft-lbs across a wide RPM range with pretty much instant response >3000 RPM.

There are always EFR turbos as well but I like the idea of running the S/C.

I'll do a build but not for a little bit yet. The main part I'm missing is a short block if anyone wants to donate one. :) I'm trying to build a complete second engine so I can keep my stock one intact. I've got a set of heads and most of the ancillary engine parts, but no block.

The cheapest wide wheels are probably the Forgestar F14s although I don't like the look of them. The key is going to be going as wide as possible with keeping the car as narrow as possible. Kits like the Rocket Bunny and other crap are not only expensive but they widen the car waaaaay too much for autox. I don't think the car needs all that much to run 315s, 275s already fit without doing anything really.


Running a 3.91 final drive may be the best option for a manual car. Revving the motor to like 8200+ RPM even with built heads may not be great since the rockers can be a weak point and shifting 3-4 times on a faster course sucks. You can pick up a complete IS250 3.91 rear diff for like $150, there are a ton of them out there.

Ah yes, the gearing. That too. More than likely I would probably go turbo if/when I do a build. Build the engine for higher revs, new final drive, do what I can to hit 75mph in 2nd.

Also curious, in my turbo research it seems as if 4th gear becomes a breaking point at 400+whp. Not that it's an issue in autocross, but wondering if 2nd gear could be a potential issue as well requiring perhaps a stronger transmission.

Where are the rest of the boosted SCCA Solo2 twins?

If someone competent got in Hyman's GTR, pretty much everyone in SM should just pack up and stay home. I'm anxious to see what Ramsey's new build can do with Mayfield at the wheel.

Jason Merritt's SM 240 car beat the GTR at the packwood tour -- both drivers :).

It's a similar recipe to PJ's car -- 315s at 450+whp with a nice ka-t powerband.

But the GTR is pretty much unstoppable, I agree. The car is so crazy to see in person. Big car doing small-car things.

To be fair to Eric... Their GT-R was down for pretty much the entire season up until that point. That course also didn't have much room for throwing down high power.

Oh I know, I run in SM. I'm aware of the score.

The GTR is stupid fast, but there's some other fast folks running around, too.

Still, it's all too rich for my pocketbook.

Based on the adaptations which are apparently allowed in SM, SM appears to be almost similar to our E1-class but those are not street legal cars:
[ame="https://www.youtube.com/watch?v=zYfNOWEOMxE"]Pure Sounds of Opel Kadett - VW Golf GTI Time Attack Frauenfeld 2012 Schweizer Slalom Meisterschaft - YouTube[/ame]

How can you still get them to be road legal? Or are the SM-cars usually put on trailers?

Street mod is essentially no cross-chassis motor swaps (but you can add forced induction), require interior in the front of the cabin, can't move suspension pick-up points, can't strip the car besides the rear interior (have to run stockish lights, bumper supports, etc), can run aero but limited as to how much.

It's sort of a dumb class, but super awesome.

And yes, every successful SM car lives life on a trailer. There is not much 'street' in street mod.

Technically in SM you can't strip any interior. Seat removal is the only exception but that just pertains to the seats and not any panels. If you remove your trunk liner, for example, you are out of SM and into Prepared classes.

You can strip the back seats out, is what I meant. 16.1.k.

Again (I think I keep telling you this) I've run SM for a handful of years now.

If someone is actually serious about SM they will familiarize themselves with Chapter 16 of the rulebook.

Hmm. SM is where stuff like the Mark Daddio Evo used to live, along with plenty of maxed out E36/E46 M3s, right?

If so then the formula would seem to be power increase + traction increase + dialed chassis + weight reduction + aero.

My dream build would be something like so...

Power:
- built bottom end
- TVS supercharger (for torque & response) with a smaller pulley + E85 or watermeth for a little extra power while retaining safety.
- clutch + axles

Traction:
- purple crack Hoosiers; 315 rear + 285 front (or maybe 315 square?) and some kind of body kit to hide it all.

Chassis:
- High end coilovers with relatively high spring rates
- Swaybars to complement coilovers
- Tons of tweaks such as bushings, control arms etc. - to keep the roll centers, alignment & scrub radius in check due to using huge, heavy rubber and presumably heavier, lower offset wheels to carry said rubber.

Weight reduction:
- The usual trunk junk
- Lightweight battery + relocation to trunk
- Washer bottle
- race seats
- sound deadening
- as much of the interior as you can chuck under the rules
- Trick lightweight wheels to offset mass gains from running huge rubber (as per above)

Aero:
- The FT86 Speedfactory front splitter + rear diffuser plus some kind of wing would seem to be a good place to start. Could then augment one end or the other to maintain balance. I've seen SM cars attempting to use flat bottoms and 'full skirt' aero though, so this could be a very dangerous area to mess with financially, although if dome well it could be hugely beneficial.

Cons:
- Gonna cost a ton of money...and even more time, setting it all up and balancing it all.
- if aiming to be co petit ice would probably take some time to re-optimize the chassis setup if coming from a lower class. Worst case - might have to spend tons 'starting over'.
- No longer so streetable.

Pros:
- Don't see why a well built SM Twin couldn't be competitive since M3s have also been, historically.
- SM cars could work nicely as dual role SM + Time Attack + DE cars, depending on your goals. So maybe a little extra utility to be had from the dollars being spent.
- Might still be streetable in a pinch.


Am curious if a less hardcore, less expensive build could be made to be SM competitive though.

For example a car with a more basic FI setup and, say, 285 square Hoosiers under the stock bodywork, with more focus on making up time using a killer chassis setup and weight reduction + aero?

You wouldn't want to stagger -- square 315 setup.

400whp is minimum.

Min weight for an FRS would be 2480 with >275s -- can subtract 200# for <275 tires.

There hasn't been a front-running bmw since Simanyi's car a few years back Recently the Panda (s14 240sx, 450whp, 315s) has dominated, and other front-runners are the evos and Stis, jason merrit's s13 (450whp, 315s, etc), the Hyman's GTR (~700?whp, 345 a7s, generally nuts), and then a few Evos and STIs that I'm sure are all ~500whp, 285s-315s, etc.