kylekim

Finally had got a chance to track my S2000 for the first time this year at Watkins Glen. Overall, it's a damn fun car to drive on track. It's not the fastest thing out there but it definitely brought a smile to my face in every corner.

Now, I tried searching for more info but I'm either awful at searching these forums (too used to honda-tech search) or I'm putting in the wrong keywords. I'm trying to confirm a couple of things and I'd like to pick the minds of this forum.

1.) Top down driving = big aero impact/drag? Since convertibles have to drive on track with their tops down (at least, at the events I attend) and this being my first convertible, there seems to be a huge impact by driving top down. I'm guesstimating everything but with the power to weight ratio and gearing, I assumed that my top speed at the back straight would be higher than what it was. After ~90mph, it felt like I hit a brick wall and acceleration was incredibly sluggish. Is this because of top down drag?

2.) Correct staggering in street tires = incredibly important? I haven't had a chance to drive on stock AP1 tires (S02s) on track. I purposely went with a compromise for cost because I'm planning to upsize the wheel/tire combo later on (the compromise tire setup is Kumho MX 205/55/16 front and 225/50/16 rear). I did notice that I lost a bit of rear tire when the tire shop replaced the S02s (blown rear tire and all 4 were dry rotting/cracking). Car felt great during braking and turn in but it felt like the car just needs more tire after turn in/mid corner. Has anyone tried a 205/55/16 + 225/50/16 and confirmed that this is just a bad thing to do? Or is the car just under tired from the get go (street tire wise) even with the factory 195ish/245ish setup anyway?

3.) The "bumpsteer" problem = should I "fix" it? I really do like the "lively" setup on the AP1s. I think it'll keep me slower and safer in a sense but still make the car incredibly fun to drive. But I did notice the glaring difference between an AP1 and AP2 after sitting in my students car. I had him going through the same line I was taking and his car didn't seem to get upset by road irregularities in the esses (high speed sweeper turns). That and he was able to get on the power earlier because the rear seemed far more stable. Then again, it might've been because he didn't screw up his stagger like I did. I'm perfectly happy with the handling in the AP1 right now but I'd rather be safer than sorry later on. Or will having more tire solve some of the stability issue (with correct stagger)?

Sorry for the long winded post but expect more as I explore/try out different things (as long as they allow S2000s on track without an aftermarket rollbar).

twohoos

2: "Correct" non-S02 rear tire is 245/45:
https://www.s2ki.com/forums/index.php?showtopic=48572

jlucas

Mostly likely the differences you felt with the AP2 were due to the fact that it has wider tires.

kylekim

Forgot about that too. Zoicks! It was a LONG weekend for me and I'm posting this the first night back at home.

Ah. Internet access. I missed you so.

mikegarrison

Top down or top up, the car has lots of drag. It is worse with top down, but not by a huge margin.

I just did a track day where I compared a session with top down (max speed 123 mph) and a session with top up (max speed 125 mph). (Speed measured by GPS, windows down.)

I imagine that if the windows were up the drag would have been less, and probably the hardtop is better than the soft top. But it's not like the top down is a stunning difference -- at least not according to this single datapoint.

Since power loss by drag goes with speed cubed, there is almost certainly a bigger terminal top speed difference than the couple of MPH I saw in my sessions.

Fongu

"Lively backend" is likely the 205/225 tire stagger.

The only time I really noticed bumpsteer issues is on mid-corner bumps on long high speed curves while at "track speeds". It really feels like the rear end swims back and forth over mid-corner bumps with the big toe curve the rear suspension has.

jyeung528

the difference you notice in the ap2 is MAINLY due to the ap2's understeering characteristics.

the ap2 UNDERSTEERS.

i have an ap1, and i say this after riding in my friends ap2. They are like DIFFERENT cars.

RACER

Keep in mind that some of the car's out there cost considerably more than an S2K. Some of them are actually modified, so therefore you can't really compare an S2K with a car that has in excess of 300-400 hp, 10" wide racing slick's, 5-8k dollar suspension ect.

SVT_Chia

I'm going through the stage of realizing this. It's going to be easier on my wallet as well. Or I could dump that money into tires, track time, instruction and more tires . I don't need a supercharger or 250whp NA to have a great time in this car. If it ain't broke....

WVtwisties

i remember hearing that in a 1/4 mile the difference between a top up vs. a top down is 1.5 car lengths (S car lengths)

I know this isn't your situation but it should give you another idea about drag.