NelsonI

I didn't want to junk up the STR setup thread further--it's already got enough BS in it, and it's a good resource on setup from several very fast guys.

Asked this question there already, but the answers were understandably terse given the context of the setup thread. I'm hard headed though and I need more 'splanation.

1) Based on everything I've read so far, I think the AP1 is the best choice for STR, not because of money, but because it's capable of 66mph with stock-sized tires, plus or minus a couple mph depending which tires you choose to go with.

2) It's also among the lightest of the S2000s. Between these two good traits, it seems like it's the best combo of strengths despite its other weaknesses.

3) I don't see how being down a few hp to the AP2s will be be slower than having to shift to third all the time, or ride rev limiter at 62-63mph. The Miatas are down 80+ horsepower (though they are 200lb lighter, give or take) and they are still thought by many to be in the running with the best of the S2Ks. Of course, they'll also be shifting to third a lot due to their short gearing.

Here's the real catch though: based on who all is choosing the AP2, I'm pretty sure I must be wrong--I just don't know why. Can you guys who are doing it enlighten me?

Is it that top speed in second is irrelevant? Is that shifting to third isn't that costly, even with the consequent downshifts? Is there some other factor, or set of factors, that I'm completely blind to?

Coming from driving an 80% prepped 350Z against the RX8 in BS (ran about 1-1.5 seconds per minute back of Carter, about even with a few mid-pack nationals RX-8 guys) it seems like their tall/high revving second gear really helped them carry speed and that their lack of power relative to the Z was pretty insignificant. Their lighter weight also seemed advantageous. The RX8 was also FAR easier to drive, meaning consistent, repeatable fast times.

This is only the end of my second season though, so I'm the first to admit I'm a long way from knowing it all; hence my trip to the mountain top here. I know some of you guys seriously know your shit.

mLeach

Put it this way, in stock, it's more of a hurdle, seeing as you can't change the rev-limiter, and the car's still get the job done. Now, in STR, they can tune the car for a healthy power bump, and they can raise the rev-limiter. Driven well, any car can win, but I have a feeling that the extra power is going to be worth it. A CR is the car. It's as light as the AP1, it's stiffer (chassis) and it's easily tuned. In an AP1, even though it has some good things going for it, besides weight (lighter flywheel, better gearing, taller rev window) it's fighting an uphill battle with tuning options the way the rules are written.

NelsonI

OK, I get that, but is power really that important? I mean if the S2K ends up being the car for the class (which is a good chance) is the 8-10hp you get from an AP2 over an AP1 (maybe more mid-range, I don't know) enough to make up for the lower top speed in second, etc? Or is that a non-factor and I should just forget about it?

It just seems that if power were so important, the Miata wouldn't stand a chance. I get why the Z doesn't: it's too heavy, even though it absolutely KILLS the S2K/Miata in power under the curve (close to twice as much torque at 2,200rpm as the S2K sees at peak, and about 90% of peak from 2,500 rpm to 6,200rpm). The benefits of acceleration don't overcome the lack of speed in second (fuel cut at 57mph with 255/40/17s) and the porky weight, which means slower cornering/slaloming.

But looking at it the other way, aside from the Z's weight, it has a ton more of what supposedly makes the AP2 better than the AP1: shorter gearing and more power. But that math doesn't compute to faster run times.

Also, tuning for higher redline is all well and good, but I'd rather not ventilate my block mid-run. I saw the reality of that demonstrated rather painfully at Blytheville last time. With the longer stroke of the AP2's engine it's going to experience far greater side loading at high rpms, so it's not what I'd call a prime candidate for playing fast and loose with the revs, meaning you won't be able to get back much of the top-end gearing lost to the AP1, even if the AP1 can't raise redline, at least not without gambling big on engine life.

And can't a VAFC push the VTEC engagement down a bit to beef up the AP1's midrange a little? I'm a complete noob to all these V-acronyms, so I could be way off base here.

Am I retarded? Is there something obvious I'm missing? There's gotta be something I don't see.

Someone slap me.

daverx7

Great topic! I wish I could contribute, but I'm going to at least watch this one.

---subscribing---

whitt1

When you bump the rev limiter to 8500 with a hondata flash tune the 06+ car will give 66mph in second plus have more low,midrange and topend power in STR,at least until a piggyback ECU is made legal in STR. If the AP2 car happens to be a CR with AC and radio delete,it will be lighter as well.The CR can also legally remove it's hard top for a further weight advantage.

NelsonI

how safe is the 8500rpm rev limit on the F22C for autocross? That's a pretty big jump, and at courses like the last several at Blytheville, there's a good chance of spending a meaningful amount of time above 8000.

I don't have the budget for catastrophically broken engines.

Also, from my gear ratio calcs, it looks like 8500rpm would only be good for about 62.5-63mph in the AP2, hence my estimation above. **edit: actually, it's more like 60-61 for the AP2 with 255/40/17 tires, less with 245/35/17s. The AP1 is still at 66+ with 255s**

The other advantages of the CR are acknowledged, but how significant are they? Enough to justify $10K in price?

whitt1

Nelson I think that a properly set up S2000 AP1,AP2 or CR, will be close enough that the driver not the car will determine the winner. I did say properly set up, a better prepared car will always have an advantage and no one has penned down the best set up for STR legal tires and mods.

NelsonI

Now the dialectic is getting somewere, though I still want to hear from the guys that have already cast their lot in one camp or the other.

I'm sure they didn't just do it at random, especially guys that ditched a proven car in, say, STS, to run in STR.

I'm not sure there's going to be a lot of difference in the final sort-out either (the AS showing tends to support this), though the CRs have had a shorter run at things, and their advantage isn't as big in STR, where many things are changeable.

TheNick

You know my feelings Nelson.

I'll take the gearing and power advantage the AP2 has over the AP1 any day of the week. The weight differences between all 3 models will come down to actual driver size. There will be barely be 50lbs difference between all 3 depending on fuel load.


And yes I'll say it again, the AP2 has better gearing than the AP1. Not worse.

My AP2 with a 9k redline gets to 64mph on 0/32nds 255 RE-11's.

I see absolutely no reason to buy an AP1 unless you can get one stupid cheap.

NelsonI

Thanks for humoring me Nick.

How do you feel about running the car up to redline? I seem to recall reading you say elsewhere that the car wouldn't be run to 9K despite the AP1 ECU? Even if not going all the way to 9K with it, how do you feel running it above 8K for multiple seconds, ala Blytheville #2? No worries of grenading it? Or is that just a cost of doing business?

I think you're right on the gearing. There would have been a bigger difference between the cars in AS if the gearing had hampered the AP2 much. I just need to fix my perceptions on that account.

Driver weight will always be a disadvantage for me, given that even at <10% bodyfat (not there yet) I'd weigh about 200lb even, so any help I can get from the car is welcome. I can't beat the little guys on this one, I can only hope to get close.

One more barrage of questions: does the drive-by-wire of the later AP2s ever get annoying? Does it cut left foot braking electronically? How about the clutch delay valve? When you switch off VSA, does it go completely away, or is there still some yaw assistance in the braking? Is that a good or a bad thing?