OK, so you've decided that the Stock class is just too slow for you, but you're not yet prepared to make the big leap to Street Modified. It's ESP for you.
Here are the essential elements of information for an ESP car:
Wheels and Tires
Number one on your list of things to do is to pitch the stock 6" or 6.5" wide wheels and get something that will support more rubber. The rule of thumb here is "wider is better". If you're on 16" wheels, the tire for you is the 265/45R16, but the trend is towards 17" wheels, with either the 255/40R17, or the 275/40R17.
The tradeoff here is that the 275 tire won't fit in the wheelwells. That means you have to raise the car marginally (.25" or so) higher compared to the 255 to keep the tire from contacting the fenders. What's more, there is some debate over if the increased diameter of the 275 (and the higher gearing that results) is worth the extra tread width.
I run the widest tire I can, and to hell with the gearing.
For offset, a +33mm-ish offset 17" X 9" wheel will fit the 255 with no problems. The 275 needs a little more clearence, but I've been running what amounts to a +8mm offset wheel by using 1" thick spacers as having 2" more track width (and the attendant reduction in roll, without needing more spring) is just too good for me to pass up.
Incidently, the Volk TE-35 in 17X9.5 +12mm is a perfect fit for the 275, and weighs 17lbs.
2005 - an even better tire is the 285/30R18 tire, on an 18 X 10 +15mm wheel. You get a shorter tire (for better gearing) a shorter sidewall (for better transitional reposonse) and an extra half inch of rubber on the road, for the same section width as the 275/17!
Brian Fitzpatrick - "Wider is better" works for wheels too. Get a rim that is at least as wide as the "measuring" rim on the tire manufacturers spec sheet. I ran Kumho 245's on a 16x8, +42mm. They were close but didn't rub.
Also, while you raise the suspension 0.25" for the 275's vs. the 255's, the CG will be raised a total of 0.5" because you have to take the tire radius into account.
Mac Crosset - Actually, I'd suggest Kumho 245/45-16's for beginners. It's easier to find a wheel that will fit, and you won't have any trouble fitting them under the fender. A 245/45-16 needs at most +40mm offset. A 265/45-16 needs less than +32mm, and then it will still rub a tad in back.
Fedja Jeleskovic - I would love to have more rubber under the car, but there is no tire wider than 245/45/16 that is not too tall for DSMs. Other sizes will give you more rubber, but increase the height of your car. Since we can't install any good camber kits in there (beside the offset bushings), choices are minimal. I even ask Kumho and Hoosier guys about a chance to have 265/40/16 tire which would be perfect for our car, but didn't hear any good replays. So, I would recommend 245/45/16 as a tire of choice for ESP.
I wouldn't be that worried with the increased gearing from the larger tire. We have to run with T25 and higher gearing would even help, since low end is great with that turbo, and any help on the high end would be more than welcome. Bigger problem is in increased height of the car. First, center of gravity is higher (which is newer good for a race car or somewhat smooth track). Second, rasing the front end just simply kills the camber that is so hard to get on 2G DSM
March 2001: The jury is still out on the "wider vs shorter" tire debate. About the only for-sure point in the wider tire's favour is that it kicks ass in braking.
March 2002: The difference in performance between the Hoosier and the Kumho has been growing steadily, to the point where now, if you want to win, you pretty well need to be on Hoosiers. The Kumho is still a pretty good tire, and is the value leader by a long shot, but it gives up about a second and a half to the Hoosier on a 60 second course.
Number two on the list is to go out and pick up a set of the RM Racing anti-roll bars. They're inexpensive, they're easy to install, and they make a HUGE difference in roll. Next to the huge tires, this is the mod with the biggest bang for the buck.
Brian Fitzpatrick - Yes!!! I just wish I could get a bigger rear bar.
Fedja Jeleskovic - As any other part of the suspension, this one has to be tuned with the rest of it. There are at least two different schools here. One is to get a big bar and softer springs and the other goes with smaller bar and stiffer springs. From what I heard so far, both works pretty good when tuned right. I also use RM Racing bars and I do like them. Although, when I had GAB shocks on the car, driving in the rain was a bit of a challenge. Bilsteins seem to fix this problem and I will try to use same spring rates over the winter too.
Next up is springs (I assume you had decent shocks when you were running GS) Do yourself a huge favour, and don't get "lowering springs". Instead, go out and get the Ground Control coilover conversion kit. This accomplishes two things: firstly, your ride height is now infinately adjustable. Secondly, the kit uses standard-issue race car springs, which are a commodity item, are available in any rate you want, and are of much higher quality than the street stuff. The up-front cost is a little more, but it's well worth it. While you're at it, get the Ground Control upper mounts for the fronts too, it gives you more suspension travel.
March 2002: Some further analysis of the way the 2G DSM front suspension works has revealed a problem with the standard Ground Control upper mounts on the front suspension. The shock/spring package pivots around a lot as the suspension (and especially the steering) moves though its range of motion. This requires that the upper mount on the shock rod not resist the pivoting motion of the shock, and further requires that the upper spring mount itself move along co-axially with the shock rod. The Ground Control upper mount (at least, the one I had) does neither of these, and can transmit some pretty fierce bending forces into the shock.
Accordingly, any upper shock mount should use a spherical bearing "pillowblock" and should have a spring "hat" that can pivot with it as an upper spring mount. The Shocktek setup had these, but Shocktek is out of business. You may be able to get Ground Control to make one for you.
2005 For a while, when I was ATI's race engineer, I was making and selling these hats. If enough people get together, I can be convinced to make more.
Spring rates are an item of even greater debate than tire size. Time and a lot of work is starting to reveal the ideal rates.
The things to keep in mind are that DSMs have very forward weight distributions, and that the motion ratio of the rear shocks is slightly higher than the motion ratios of the front shocks. This leads to using a lot more front spring than rear spring. My current setup is 900/400 front/rear.
The temptation is always going to be to crank up the rear spring rate (or the rear bar rate) in order to get the car to turn. Resist temptation! What you are doing is sacrificing rear grip, and overall grip, in order to balance the car. Don't unstick the rear, stick the front!
Note to run spring forces this high, you need very good shocks. Note too that properly matched shocks will use a lot less shock force than you might expect - stiff springs, soft shocks is the way to go. The suspension must be able to move. Done properly, the ride is actually pretty confortable. If you are pissing blood after a drive, your shocks are probably too stiff.
Fedja Jeleskovic - My current setup is 650/550 front/rear and car is pretty nice. One of the problem here is that front upper control arms still bottoms out and hit fenders sometimes. That forces you to have front a bit higher than I would like. One of the ways to fix this one is with correct bump stop bushings. Unfortunately this one just hides the problem and it is not complete fix. I will try to use stiffer springs in the front (probably 750) and see if that is going to keep my fenders safe. More stiffness in the front will stabilize the rear end a bit more which is not the best thing. Hopefully, additional camber in the front will offset this effect and car might be the same as it was before.
Brian Fitzpatrick - I just put a set of 400 lb/in springs in back (were 325's). My fronts are 500 lb/in.
Mac Crosset - I'm running 300's, and the only reason I haven't gone stiffer is the ride on the street.
2005 My SM car ran 900/400 with the OEM rear bar, and it was about perfect. It was also a good deal lighter than the average ESP car, so an ESP car should want a touch more spring.
March 2001 - One of the things we've learned over the past couple of seasons is that shocks matter. Proper shocks can make a huge difference in handling. Even more intersting, is that different shocks have entirely different response curves (it's not just a matter of softer/stiffer) The Konis have a very stiff initial dampning, but then they "blow off" and get softer. The ShockTeks (Bilstiens) are much more progressive. When we switched from Konis to ShockTeks, we wound up stiffening the springs by about 100lbs.
March 2002: Fedja has had good luck with Penske shocks, sourced (I believe) from Guy Anakey
Fedja Jeleskovic - I am using a custom made set of Bilsteins from the ShockTek and usually run them 1.5 turns off the full stiff. Unfortunately, that is not very useful, since different revalving of the shocks will require different settings. Overall, these shocks are much more gentle from the GABs that I used for the 2 seasons. Car is extremely comfortable (considering very stiff springs) and in some comparisons came out less bumpy than AGX shocks with mild springs. Since, they can be revalved to fit any need, they are very nice for racing and they can help you to tune your car very nice.
Brian Fitzpatrick - Last year, I ran my Koni's at half-stiff (1 turn) front and mostly-stiff (1.75 turns) rear. The car was well balanced in transition, but it understeered in sweepers. With the new rear springs, I hope to either stiffen up the front shocks or loosen the rear shocks for neutral handling in transition and sweepers.
Mac Crosset - I'm running GAB's at full soft for a bumpy course, and 2 (of 4) on a smooth course, and the rear depends on the course...full soft for a bumpy, sandy course, full hard for smooth, grippy concrete. I also vary tire pressures depending on surface, but usually around 38/34.
The last thing you need is a set of offset upper control arm bushings, to try and get at least -2 degrees of front camber, and -3 degrees would be more like it. You can get -1.5-ish just by lowering the car, but thæt extra degree is worth the effort
Mac Crosset - The lower control arm bushings I hade made last season didn't work out so well. They needed to be softer to allow some lateral movement of the control arm. Also, remember that by adding negative camber, you reduce braking and acceleration. I did notice more wheelspin with the bushings.
Brian Fitzpatrick - I'm having new offset control arm bushings made. The uppers will be Delrin, and the lower will be polyurethane (95A, I think).
Fedja Jeleskovic - all the upper control arm bushings (front and rear) are made of Delrin. I might change lower ones in the quest to gain even more camber in the front. Another option that is very nice (for both camber and caster) is to use 97+ lower control arms in the front. This works only for the 95 and 96 cars, since they have somewhat shorter original control arms.
EngineNow that we've got the suspension sorted out, now we can look at the engine. The important thing to remember here is that you absolutely, positively, under no circumstances touch the turbo, the BCS, or the vacuum lines that connect them. Just leave all that alone!
Don't worry abount being down on top end with the T25 - we've discovered that with the BCS active, (as it MUST be in ESP) the T25 is a better turbo. It's all about spool, and low-end here. The secret to winning with a Talon is getting back on the gas as early as possible in a corner, so spoolup is what we're worried about.
March 2002: There are some rumours being spread around that I removed the little restrictor from within the BCS when I was running ESP/GS, properly known as "cheating". This is untrue. I did some tests with it out for drag racing, but it was always in place whenver used on an autocross course. DG
To that end, you want an upper intake pipe, one that mounts a (legal!)* 1G compressor bypass valve. Do this first. Buschur makes the best one; it's far straighter than any of the other ones available. If you don't have one yet, get a boost gauge. As well, get a K&N cone filter, cut the CBV downtube out of your intake hose, and consider replacing the lower part of the intake hose with a metal pipe.
Mac Crosset - Note that the cone filter will greatly increase intake temps on a hot day, up to 40degF over ambient, as it ingests air from the engine compartment. You should really block off the cone filter from the rest of the hood. I'm still running a stock airbox.
Brian Fitzpatrick - Someone needs to make an airbox for the K&N that gets air from under the car. I know it can be done, but it would be a bitch to fabricate. I have some high-tech cardboard blocking off the air filter.
Fedja Jeleskovic - I also added some kind of air block plate in there and it is definitely a way to go. You can see a temperature difference between the metal K&N parts and the rest of the engine. Since I had to go through the engine rebuild process, my head was cut down 0.010" and it looked like that there was some increase in the throttle response with that head in the car. I don't think that taking the head off the car just to cut it that much is a smart thing to do. The thing is, if you have it out of the car it might be something to look at. Head in my car was warped so I had to do it. Not if that head goes bad, I would need a new one since it can not be cut any more (both due to the Street Prepared rules and the actual allowance from the head and valves it self). Switching to the new type lifters (they have larger oil holes at the top) is another smart thing to do and decrease amount of the valve ticking that is typical for the DSMs.
Now the clincher - get at least a 2.5" diameter, turbo-back exhaust (with no cat!), and consider getting the 3" system. However, do NOT port the O2 sensor housing. With all that downstream flow, the turbine has no problem spinning, but the restictive O2 sensor housing restricts the flow through the wastegate bypass. The result? The wastegate is incapable of controlling the turbine, and you get boost creep to as high as 21 lbs of boost, for a very brief transient (the T25 is NOT capable of holding that pressure for more than a fraction of a second, and you will drop to 11 PSI or so by redline - anyone who claims differently is either lying or badly misinformed). But for that instant where you are making decent pressure, you get a nice big shot of torque - and because this is a T25, that happens down low, where you want it, exploding out of corners.
At this point, you've got 75% of a National-contender ESP car - once you've got the setup dialed in, at least. DO NOT underestimate how much time and effort this will take. Just slapping on the parts is no promise of speed!
Everything else after this point is mostly little stuff - strut tower bars, a good set of race seats, lots of de-optioning, harnesses, etc - to try and get the weight down.
Some areas that havn't received much attention yet are: ECU tuning, the effects of a front LSD, drastically lightened flywheels, larger throttle bodies, Extrude-Honing the intake manifold, and so on. Go forth and learn! Not all the secrets have been learned yet!
March 2002: It seems that adding a Quaife front LSD turns out to be spectacularly effective. It pretty well eliminates the power-on corner-exit push that often plague DSMs. However, using it sucessfully seems to require the Quaife centre LSD as well, as the time lag involved with the centre viscous coupling locking up can induce some pretty hairy handling transients when it does lock (thanks, Eric Stemler for reporting this)
So an investment in a pair of Quaifes is money well spent.
A Talon prepared to this level is capable of trophing at Nationals, assuming the driver is up to it. It also runs dead reliable, and is still perfectly suited to daily transportation. It's also a whole lot more fun to drive. :)
Thanks to Mac Crosset , Fedja Jeleskovic and Brian Fitzpatrick for their comments and input