2008 Street Mod Discussion

[EVOlutionary]

Welcome to the 2008 Street Modified autocross discussion. This thread will be a place all SM competitors can share our exploits throughout the year, and also will serve as a resource for competitors thinking about campaigning an EVO in Street Modified class.

The last Street Mod thread has really grown! There is a huge amount of information contained in there and I would highly recommend any folks new to SM take the time to read through the 800+ posts before starting in the 2008 discussion. You can access the 2007 Street Mod thread here:
Autocross EVO - Street Modified Build

One question I had asked in the old thread I think is worth bringing up again -- What part or technology that is not currently used on the EVO do you think would improve your SM EVO's performance??

EVOlutionary

[EVOlutionary]

Here is an update on what I think it takes to build a nationally competitive Street Mod EVO based on what I've learned the thoughout the past year. . .



WHEELS AND TIRES
The standard is 285/30/18 Hoosiers A6's on an 18x9.5-10 inch rim. Wider is probably better. If you can cut the fenders and/or install a widebody and run 315 or 335 tires, I think that would be best. Of course go with the lightest, strongest wheels possible for your budget. FN01R-C's are popular because they are inexpensive and average weight. It seems that running staggered width rims (1/2-1" wider in front) has gotten more popular. I am not convinced that it is necessary, although some may do it more for convenience than performance. It is not easy to fit a 10-10.5" rim under the rear fenders. . .

SUSPENSION
It's quality, not quantity. You can have a big $$ set of shocks, but if they are not optimized you will get whooped by someone with perfectly tuned JICs. Unfortunately, at the National level, there are not alot of guys who will just give you the setup they are running because they have hundreds of hours and lots of $$ of testing invested into it. All I can recommend is to become friends with someone who knows alot about suspension and work with them/learn from them. Trial and error. Run your shocks full soft. See how the car feels. Run them full hard. See how the car feels. Then work in from the extremes. Most folks run a rear sway bar, some a front sway bar. Some crazy guys run no sway bar and super stiff spring. The combinations are limitless. You want your car as low as possible to lower the CG, but you need to me mindfull of roll centers. The Whiteline Roll Center kit seems to have been a popular item this past year. . . My suggestion - talk with Navid, Andy, John, Mark, Eric, Robi, Paul G, Marshall, etc. and learn as much as you can as far as what it takes to make the EVO stick.

POWER
MY FAVORITE! It is my opinion that you will need between 400 and 450WHP to win Nationals in an EVO. Some guys run less, some guys run more. I, personally am in the middle of that range. Too much low end torque is not always good. If you have really hard hitting power coming out of corners you will spin tires, as the EVO is very prone to lifting wheels and getting light on the inside tires. Too much torque can also cause too much oversteer. A 2.3L stroker with a TME turbo is probably not the best way - too much TQ and not enough top end. A 2.0L with a 20G variant, or possibly a 2.0 or 2.3 with a 50 trim I feel will be optimal. I recommend a built motor that can rev to over 8000rpms. Instead of riding the rev limiter in 2nd gear (or *gasp* shifting to 3rd) and losing time and accelleration, get a built motor and take it all the way to 9000 in 2nd gear. With the 285's that should get you to about 75mph. Alternatively, you could get the HKS 4.11 final drive gear so that you can go faster for the same RPM. Smooth power is key. You don't want compressor surge, BOV stuttering, or anything like that at part throttle. The throttle input should feel as though it is directly liked to boost pressure (just how a stock EVO feels).

WEIGHT SAVINGS
There really isn't a WHOLE lot you can do. Start with an RS so you have the aluminum roof and no ABS crap. (many people swear ABS is faster, but I am not convinced, yet. . . ) Lose the back seats and rear seat belt stuff. Get light weight racing seats. Get harnesses that attach to the rear seat mounting points rather than a harness bar. Harness bars are pretty heavy, and high up in the car. Get rid of AC and stereo stuff. Light weight clutch, driveshaft, brake rotors, wheels, etc. to save rotating weight. Consider keeping the stock FMIC - those big aftermarket ones weigh a ton. Consider a small radiator - you will save weight on the radiator itself, plus water weighs like 9 pounds per gallon or something.

AERODYNAMICS
To be the fastest in a big heavy car like the EVO you need every advantage you can get. Run as big of front splitter as you can. Splitters make downforce. Downforce gives you more grip. Some people set up the car to be loose in slow corners to help rotation, then use a big rear wing to stabilize it in high speed corners. But, having too much rear downforce without matching traction in the front is not going to be good. Make sure your car is balanced. Once again, run as big of a front splitter as possible, and one that is properly designed. Just a flat piece of FRP or carbon bolted under your front end may give you some benefit, but is not optimal. Take a look at the Voltex big splitter on the Cyber EVO for one that looks like a well thought out design.
As a side note, I hope that the SCCA "keeps up with the times" and does not continue to shy away from aero modifications, especially in Mod and Prepared classes (including SMod). Looking at Japanese Time Attack cars and German DTM cars shows just how prevelent aero is in other parts of the world. I think America is playing catch-up a little bit in the tuner car aero field. . . (Heck, it took NASCAR 40 years to learn what a wing and splitter are! )

DRIVETRAIN
There is a lot of variation here. You may be able to get away with a VCU center diff and stock F+R LSDs. You will see some folks trying the GSC 40/60 center diff. Right now my car is tail happy enough, don't think I want to experiment with MORE rear power! Currently I run a stock front LSD, stock center ACD, and TRE reworked rear LSD. Stock tranny is fine. Probably won't break one at the power we will be running. I would recommend you have your transfercase built if you own an '03-'05 EVO. Lightweight clutch, flywheel, and driveshaft will all get you from corner to corner quicker. The Exedy Twin is the gold standard clutch.


Of course how much of this stuff you need is all dependent on your driving ability and how competitive you want to be. A great driver can win with less modifications. A more mediocre driver will need a more capable car to be as fast. The cheapest modification one can make that will yield the largest gains on the race track is to attend an autocross school. This can be simply one put on by your local region all the way up to the full EVO School program.

Please feel free to add to or argue with these opinions - that's what this forum is for!

EVOlutionary

[Matt2.8NJ]

Sias M3 For sale... nice buy @ 36k!

http://www.siastuning.com/yellow4sale.htm

[evobeatsti]

the sias bmw was really ghetto, all the body parts are like falling off and are taped on...

[Warrtalon]

Oh, come on, yours was ghetto. The Sias-mobile was pretty sharp.

[EVOlutionary]

So if Daddio sells his car and Sias sells his, then can we just proclaim me the 2008 champ now??? Or are you all going to make me WORK for it?? I HATE work!!


Dang, it was worth a try!

[EVOlutionary]

Wow!! I just looked as Sias' specs and I'm surprized - I'm makin over 80HP and 200TQ more than his BMW. That beast revs out to 8800rpms, though! It sure does sound wicked in person . . .

[kduncan01]

Subscribed!!!

[evobeatsti]

Originally Posted by Warrtalon

Oh, come on, yours was ghetto. The Sias-mobile was pretty sharp.

w/e clayton, i was on like a $4k budget, my car is going to be legit this year haha.

what was the most ghetto part to mine in your opinion? the badly vynled side skirts, or the lip that was falling off or the blue masking tape?? jk

Originally Posted by EVOlutionary

So if Daddio sells his car and Sias sells his, then can we just proclaim me the 2008 champ now??? Or are you all going to make me WORK for it?? I HATE work!!


Dang, it was worth a try!

my co-driver will make you work for it lol, also what if really good drivers buy mark's and vic's cars?

[chrisw]

Originally Posted by EVOlutionary

Wow!! I just looked as Sias' specs and I'm surprized - I'm makin over 80HP and 200TQ more than his BMW. That beast revs out to 8800rpms, though! It sure does sound wicked in person . . .

that and sia's mutant driving ability combine to make a formitable combination.

It will be interesting to see what he drives next year.

[EVOlutionary]

Oh, I didn't even think about that! What if he builds a new car for '08???

[kekek]

Originally Posted by EVOlutionary

Oh, I didn't even think about that! What if he builds a new car for '08???

He mentioned an evo over on sccaforums

[evobeatsti]

Originally Posted by kekek

He mentioned an evo over on sccaforums

NOOOOOO!!!!


haha that would actually be sick, i would love to see what he came up with.

[EVOlutionary]

I have a good one for sale for $19K!! Already has all the basics like poly bushings, roll center kit, bump steer kit, poly motor mounts, TRE tranfer case, Quaife LSD . . .

Dude, how bad would it suck to get beat by my own car!!

[chrisw]

Originally Posted by evobeatsti

NOOOOOO!!!!


haha that would actually be sick, i would love to see what he came up with.

I'll let you know in 2 weeks after the first unnofical event of the season.

Vic has driven EVO's before and knows what they are capable of. I wouldn't be surprized if he picked on up.