SCCA STX E30 Build/Introduction

[Jean]

Yeah I know how much they cost, ran V710s this season with co-driver. I just didn't realize you guys ran those in E-Stock? Why not CSP?


Anyway, good luck with the build and I'll be watching this ! :)

I just finished running SM with a co-driver and we finished 1st/3rd in local chapter, our times were faster than ST civics but slower than fastest CSP miatas normally. But got a few things planned for next season to change that, no way am I going back to street tires though lol GRIP is sooo addicting.

[race2win]

The civic hatches in ST are way lighter though. Can you post their weights/power/size to compare?

Civics are around 2000 lbs, 105-ish WHP, 195 tires, not sure what the width is but they are narrow. Yes, they are considerably lighter, but the point is lighter-is-better, & I hope to use that as an advantage with the E30.

I won't need to run ST Civic times to win STX next year (they will no longer be able to run STX starting 2012), I figure I can still be a second slower than an ST Civic & still win STX! :D

[race2win]

$1100 hoosies for E-Stock class? I can see that for CSP but not for E-Stock, but that's looking the local chapter and the fastest CSP cars...not many E-Stockers here.

$213 each from Tire rack, plus shipping, plus mounting/balancing Not quite $1100, but over $1K...

In the Miata we get about 30-40 GOOD runs, then they start to fall off. Thank God Hoosier has contingency at the National level...A win at a National Tour or Pro Solo gets 2 free tires...myself & my co-driver finished 1-2 in San Diego this year & got 3 tires out of it 8-) But if you don't do national level events, R-compound tires can be spendy to stay up front...one of the reasons I am jumping to STX next year.

[Jean]

The civic hatches in ST are way lighter though. Can you post their weights/power/size to compare?

[race2win]

Thanks for the comments guys, here's a little more background as to why I'm chosing an E30 over the more common cars in the class. YES, it will be a challenge to get the car up front, but that is what makes it fun for me...taking a car most think can't get it done & being successful If I wanted to keep winning whenever I wanted, I would just keep running the Miata, but I like the challenge this car presents!

Here is a breakdown of noteworthy specs of the cars in STX, these specs are with STX legal mods...

92-95 E36 325i/is - 180-190 WHP, 2800 lbs, 255 tires, 66.8" wide
96-98 E36 328i/is - 200 WHP, 2900 lbs, 255 tires, 66.9" wide
04+ Mazda RX8 - 185-200 WHP (but no torque), 2700 lbs, 265 tires, 69.7" wide
88-91 E30 M3 - 160-ish WHP (not much torque), 2650-2700 lbs, 245 tires, 66.1" wide
87-91 E30 325i/is - 150+ WHP, hopefully 2500-2550 lbs, 225-245? tires, 64.8" wide

So as you can see, the E30 325 is out-gunned on paper in outright power & tire size. However, the absolute #1 most important thing in autocrossing is weight...or lack-there-of ;) The E30 will be a lot lighter than all the other cars, & it's at least 2" narrower than all of them. There is a reason 89-91 Honda Civics DOMINATED STX the past 2 years at Nationals, light weight & narrow is KING! The Civics have much worse power-to-weight ratios than any of the above cars, & even the tire-to-weight ratio isn't substantially better, yet they covered the fastest non-Civic by more than 2 seconds on day 2 this year .

Nsquared97, the MAF must be stock. I'll be honest, I have not read up on the Millar War chip, but another E30 STX competitor (Doug Hitchcock) mentioned possibly trying one, so I assumed they would be legal. I will do some more research on how they work...

Rear diffs must use stock final drive ratios...so it must stay 3.73 in these cars. However, you can use any limited slip unit within the stock case. I believe max in 2nd gear will be right at 60 MPH @ 7K RPM.

[Jean]

$1100 hoosies for E-Stock class? I can see that for CSP but not for E-Stock, but that's looking the local chapter and the fastest CSP cars...not many E-Stockers here.

[Nsquared97]

Subscribed, I definitely want to see where you go with this. Hopefully I will be following this path a couple years down the road.

As far as tuning, you mentioned the WAR chip. Out of curiousity, do you know if their MAF conversion is legal wihtin Street Touring rules?

Also curious, have you looked into what gearing the 3.73 will give you? I know some other guys run slightly lower ratios to be able to stay in 2nd longer. Do you see that being an issue at all?

Good luck and I can't wait to see the progress! Oh and very clean car BTW :up:

[bmwguy325is]

Tough car for STX. You have to deal with the subarus.
An E35 328 will own you. An early one only has 200ish pounds on an E30 and they have more power. Not to keep you from trying.
As for your exhaust. A long tube header is the only on that will make any power and thats after you tune it. I say get the miller WAR chip so you can really get a good tune in the car. As for you plans to run a down pipe I can tell you now it wont pass sound. My car with a full 2.5 inch and muffler tweaked the very limit. Course you have to retain a cat so your will be alil quieter.
As for a diff. OS Giken GREAT but $$$$ A nicely rebuilt OE diff can be just as fast.

[race2win]

Hey everyone, I've been lurking here for a while through the ownership of my last 2 E30s. I thought I would finally introduce myself & my car, & figured the Track & AutoX section would be the most fitting place to do that since I intend to build my E30 to contend at the national level in the STX class in SCCA autocrossing. I apologize in advance, this is somewhat of a long read :oops: But hopefully my knowledge of autocross & the trial & errors of this build will be helpful to the members here in the future. So first off, a little about me & what I hope to accomplish...

I have been autocrossing for almost 20 years now in various cars from the stock to street modified level. I have countless local & regional victories, as well as some Divisional, National Tour & Pro Solo championships. Most of my success has been behind the wheel of Miatas, as quite simply they are the fastest & most capable autocross car there is. But I am ready for a change, & for the 2012 season I intend to prep my E30 to compete at the National level in the SCCA's STX class. I believe the E30 has what it takes to win STX, but most in the autocross community rule it out for various reasons. My goal is to document my build process here in this thread while including all of the experts here on set-up ideas, to ultimately provide an easy-to-duplicate in-expensive build that others can follow in the future :mrgreen:.

SCCA STX rules for those that don't know...

The street touring category is the most popular in SCCA Solo, & continues to grow each year. In a nutshell, the cars are stock with the following exceptions

- Emmisions-legal engine bolt-ons limited to intake, exhaust (with cats), chips/re-flash or any ECU programming in the stock case. Otherwise engine must be totally stock & original...no bolting in a "i" motor in an "e" ;)
- The suspension is mostly open allowing most any shock/strut/spring combo as long as the suspension type stayes the same & the original pick-up points & geometry is used. Any sway bar, strut bar, camber plates, etc.
- Transmissions & diffs must be stock, but any limited slip unit can be used.
- Interior must be stock, but race seats can be used, harnesses, any steering wheel, & any shift linkage.
- One of the most desirable aspects of the category though is the tires...no R-compound tires allowed like in other SCCA categories. Only street tires with a minimum of 140 treadwear are allowed, so the tire budgets are more managable than the other categories (it takes a minimum of 2 sets of $1100 Hoosiers to stay competitive in our E-Stock Miata each season, & those are 14" tires!).

Currently, the STX class allows most 2 or 4-door coupes/sedans from 2.5-5.1 liters normally aspirated & 2.0 liters or less forced induction. The current cars-to-have are 3-series 6-cyl BMWs, 02+ 2.0 liter Subaru WRX, Mazda RX8, & the E30 M3. Each of these cars has strong points & can win, but compared to them the 6-cyl E30 is lighter (as much as 300+ lbs lighter), & it's narrowerer, meaning it should get through slaloms & transitions very well. It does have less power, but the power-to-weight should still be very close, & more importantly it has one of the best tire-to-weight ratios.

About my car...It's an 89 325i 2-door. I have now had it since Early March, I bought it from the 2nd owner who had it since the late 90's. He & the original owner had garaged it 95% of the time, so the original Zinnoberot red is beautiful :) It currently has Bilstien Sports with Vogtland springs, H&R sway bars, cat-back exhaust, CAI, MarkD chip, Z3 shifter w/ZHP knob, Momo wheel, "is" front lip & rear spoiler, 15x8 TR Motorsports C1 wheels with 225/45-15 Hankook RS3s, & a few other things.

Here is what I plan to do to the car in the coming months, please chime in everyone with ideas, especially on supension developement.
- Coil overs with front camber plates...looking at AST, TC Kline, & Ground Control, but leaning toward a double-adjustable Koni set-up from TC Kline. I need ideas on spring rates though...
- Sway bars...I'm probably going to ditch the rear bar all-together, I hear that is a popular set-up, plus it takes off some weight ;) Still deciding on front bar...
- Exhaust...Looking for a header that provides good mid-range power & still pulls to 7K, then I will have a custom very light single exhaust built with a high flow cat. Also considering building it with a pre-silencer with a flange on the end so I can just run a turn-down that exits under the car. That would be the lightest set-up, but may not pass sound at some events.
- Race seats, no real preference here, just something light (25lbs min with brackets) that doesn't restrict upper body movement too much.
- ECU/chips...I like my MarkD, but I may go to something more tunable like the War chip, or maybe just have Mark build me a custom tuned chip based on my A/F ratios...
- LSD diff...the original open 3.73 diff is still in the car, but I have a S3.73 waiting to bolt in. The question is, rebuild it with 2, 3, 4 clutches, or spend the $$ on an OS Giken or KAAZ unit? I'll probably just start with rebuilding it with 2 clutches & see what the traction is like...

That's about it for the first stage of this build, once I get all that put together it's time for testing :D I will continue to update this thread as I go along, but please chime in if anyone has any ideas, comments or suggestions! Sorry for the long read, hopefully this will be a great starting point for future E30 owners that want to get into autocrossing.