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Originally Posted by BigBrother
First - to reiterate, yes, we are in DSP.
Second - Poly mounts are legal in STX, and so is HP Tuners. You can't change the injectors in ST, but you COULD get the stage 1 flash to get the higher redline and retune w/ HPT to keep your 42# injectors. As long as you run premium fuel only, you should be fine. Regardless - you don't have to run in SP if you don't want to just becuase of poly mounts.
Third - I think you'll find that tire idea not as swell as you think. Try it - you may be right and I wrong - but that's a LOT of tire under a car and almost all of the extra width will be outside. That's good - except it changes your scrub radius DRAMATICALLY, which will make the cars turn-in awkward. Also - hard to tell how the EPS will handle it. I really think that lowering the cars CG and tuning the suspension properly in conjunction with 245/45/17 rubber would out-handle a stock ride height on really wide tires. Maybe not out-grip, but certainly out handle. Autocross is a grip race - but it's also a handling race. If it was an oval with constant radius turns, sure - but it's not. I think you'll learn to hate slaloms with those shoes on. I could be wrong though... Oh - and your math is WAAAAAY off. a one-inch increase in radius - almost 2" overall diameter - is a LOT more than 1%, lol. In fact, it's almost 10%. I'm all for gearing it up a little for 1st, but teh VAST majority of an autocross course is spent in the middle of 2nd. I wouldn't want to lose that much gearing in the sweet spot to gain a tad more throttle at exit, dude. Modulate the throttle better, lol. A rear sway and stiffer springs - a good bit stiffer in back - will increase the effectiveness of the stock LSD many times over, so put some trust in it. Or try a very light left foot brake action with the hammer down leaving a corner - works wonders for getting teh LSD involved if you're getting too much spin. Oh - and more negative camber, too. I've got -2.5/-2.7 on stock suspension on 245/45/17 Hoosiers, and it's not enough according to the pyrometer. If you're not taking tire temps, you don't know if your camber is right.  |
Many short responses:
Actually, the figures are diameter, not radius (at least according to the spec sheets), I've already hit the rev limiter in 2nd with 225/45 x 17s on some autocross tracks (granted, most often at turn-in to the following big turn) but I hit it multiple times with 225/40 x 17s in San Diego at the National Tour Event there on each run, I have the stiffer rear sway and if I really need to stiffen the stock springs -- I'll use 'spring rubbers' ala NASCAR to add stiffness without changing the ride-height, I've seen the results of 245s and they aren't a dramatic improvement, I've considered moving up to 255s or 275s but the available aspect ratio (45) means a substantially 'taller' tire -- so the choice is move futher up to 297/315 or sacrifice more gear ration, I've used a light left-foot brake in an attempt to add 'load' to the LSD (the quaife is a 'torque-limiter' LSD, so no torque, no LSD) and I modulate on exit, I have run as much as 3.5 degrees of negative and the trade-off between accelleration slippage (LSD torque loading again) and corner stick didn't make it better, I own and use a pyrometer, I understand the scrub radius issue and accept that some initial toe-in will be required (probably as much as 1/4") to improve turn-in -- bottom line: it will be an interesting experiment...
BTW, one of the reasons I'm jumping from DS to DSP is that I don't like running with 'street rubber' (STX, etc.) -- slicks are more fun...
For the earlier response, I have multiple vehicles ,and since I commute 150 miles/day, and with the cost of 91 Octane, the Redline will remain a 'hanger queen' that gets driven 'only on Sunday at the races', so to speak. If I ever put it on the street again, I'll go back to stock injectors and flash and stock suspension settings.
At the two National Tour Events I've run over the past couple years, Texas City, TX and San Diego, CA, there were no tight slaloms -- high speed slaloms and a couple of quick 'off-sets' -- but no tight slaloms. So the set-up I'm planning to run should be perfect for what I've seen.
I like the thoughts, though. It seems like this thread is getting the serious autocross competitors on line -- and I appreciate it. We have to get back to the 2.4 issue, though -- next post.
Thanks for the thinking,
Scott