The Forumula for RX8 Victory in STU Class Autocross

Post by **Brian** » Sun Jul 17, 2005 2:00 pm

Today was the first autocross on our full STU package. Previously had many suggest that the RX8 was just NOT going to be competitive in the STU class with the 300 and more horsepower Mitsubishi EVO and Suburu STIs. However, because the of the horsepower gap the SCCA limits the rally EVO and STIs to 245 mm wide tires while the lighter RX8 can run 275s all around...which should mean it is more or less competitive depending on the course design. Today we proved that.

Today was our first autocross on our new Falken Azenis 275/35/18s on 18x9.5s all around with JIC coilovers and Racing Beat Sway Bars, Porterfield R4S pads, and a reasonably aggressive alignment....and a proper corner balancing. We took FIRST place in STU. It was close but given the errors I made as a driver and still first place I think we can reasonably conclude that the RX8 is at least a competitive STU car. Looking forward to proving the success of this package again at the next event.

NVMyRX-8 · Post by **NVMyRX-8** » Mon Nov 07, 2005 4:18 pm

I was wondering how this STU package is working out on the RX-8?
Have you autocrossed it more?

Post by **Brian** » Mon Nov 07, 2005 4:48 pm

Just a few times. Result depends on course design. If it is tight than our superior grip as compared with the EVO and STIs (limited to 245 wide) gets us a good finish but if there is any long straight where those cars can use their power then we don't place so well.

Also using it on track days and on tight tracks like "streets" of Willow Springs it has proven very quick and a lot of fun.

gh0st · Post by **gh0st** » Sun Nov 13, 2005 10:44 pm

hey brian, i want to run a stiff spring and shock combo for local southern California road racing events like at the streets of willow. ive been looking into swaybars and i have a question.

mazdaspeed seems to address the bodyroll issue with stiff springs and shocks and a light swaybar. racing beat on the other hand seems to rely much more on the swaybar to eliminate roll and provide only marginal stiffer springs. since you have the JIC coilovers wich is about twice as stiff as the mazdaspeed setup and the racing beat sways (also pretty stiff), i thought id ask you on how stiff you feel the 8 should be to be competitive and when is suspention concidered to be "too" stiff.

denward

Post by **Brian** » Mon Nov 14, 2005 9:46 pm

Competitive with what is my first question? Note that the front spring rates on the factory RX8s for touring car championship are 800 pounds...far more than any of the choices we're discussing here.

But, driving 800 pound springs to work every day can get a little rough. Racing Beat follows what is often referred to as the "Lotus" school of suspension design with high rate sways and relative light rate springs. The "advantage" of this style of setup is a pretty reasonable overall ride quality despite a pretty high smooth surface lateral G. May not get you up and tight with the factory race RX8s but gets you pretty good without beating you up on the daily drive. The MazdaSpeed combo is also a compromise for the daily driver but a slightly different mix. Frankly, I can't say which is "better", different ways of accomplishing the same thing...a reasonable dual purpose setup.

Which brings us back to your application. As always, the question is: how much ride quality are you willing to give up for track performance? I would use that answer to decide springs first. The common misconception is that sways do not impact the ride quality, but they do...just much less than the spring and damper selection.

Guest · Post by **Guest** » Tue Nov 15, 2005 9:55 am

i use my car just on the weekends and will eventually (if i dont end up getting my friends c5 z06) probrably just road race/autocross it so i dont mind losing all ride comforts.

i am a frim believer that the car can be too stiff. i guess im no where near that for the setup i want. the springs my buddies bought me are the vogtland springs which are 275lb/in front and 280lb/in in the rear with load. the drop is 1/2 inch in the front and 1 1/4 in the rear. with shocks such as konis or tokiko d specs, would i be competative vs people with the high end coilover systems?

as of right now, i probrably will end up getting racingbeat sways and switching to 9.5 inch wide wheels. cant decide between 17s or 18s. i like 17s for the agressive gearing but i havent been able to find any that are as light as your wheels.

denward

Post by **Brian** » Tue Nov 15, 2005 10:23 am

Yes, I think that if you add the wide rubber, Koni shocks, and a front sway you should be pretty quick on that setup. My guess, without knowing the rest of the setup, is that it is currently a little tail happy at the limit now with those spring rates....but adjustable Koni and stiffer front sway can fix that.

gh0st · Post by **gh0st** » Tue Nov 15, 2005 12:08 pm

funnny you should mention oversteer. as of right now, my pace in the canyons has chnged quite a bit. my entry speed is faster but i fond im on the gas later because of my fear of oversteer. i dont like to push it on public roads anyways. i also noticed that my brakeing has suffered too since the springs. my abs kicks in much earlier and it kills my confidence. its probrably for the better though. dont want to kill myself before i make it to the track.

denward

Guest · Post by **Guest** » Tue Nov 15, 2005 8:07 pm

that must be a typo on the rear spring rate, the rate spread isn't anything like what the other sport spring suppliers are using, maybe 180#/in?

Guest · Post by **Guest** » Tue Nov 15, 2005 8:15 pm

BTW, looks like we're going to see what a full tilt STU setup can do

9.5" wheels received, shaved 265/35 Yokohama Advan Neovas on their way, header on it's way (trying to decide between custom cat pipe vs aftermarket), getting ready to send a PCM to Italy for a $2600 internal makeover, planning a custom DA coilover conversion on a set of Konis, custom swaybars, and it's only the beginning