BRZ vs S2000 vs Cayman S (my take)

[ZDan]

Originally Posted by jsimon7777

I have spun out on turns 3 and 6 at Thunderhill and turn 4 at Laguna Seca (in the rain). All the times I lose grip are at the end of the turns when I'm on the throttle after going in too hot. No sudden moves. No jumping off the throttle. Not floored. Stock FRS suspension + front crash bolts + zero toe + ESC off but no pedal dance? Mechanical variance? I dunno.

Could be the outside rear bottoming out and giving a rapid rise in rear roll stiffness. That would be my bet, as these cars are known to have very little compression travel at the rear before getting onto the factory bump stops.

Considering that, I kinda take it back that you will *always* get more relative understeer getting on the gas, as I think about it this is precisely a case where you would get more oversteer!

In any case, it is good to talk these things out

[WolfpackS2k]

Guys, SERIOUSLY. Please stop butchering my thread.

If you want to start a vehicle dynamics discussion please do so elsewhere.

[juliog]

You mean the BRZ vs S2K vs Cayman debate isn't settled yet?

[CSG Mike]

Originally Posted by jsimon7777

Maybe my car is weird. I know what understeer feels like. I understeer like mad all day in my Fiat 500e. I have gone off wide three times and spun out three times in the FRS on track days. The wide offs are when I felt the rear coming around so I straightened out. That was at the end of turn 3 at Laguna Seca, turn 9 at Big Willow, and 15 at Thunderhill. I have spun out on turns 3 and 6 at Thunderhill and turn 4 at Laguna Seca (in the rain). All the times I lose grip are at the end of the turns when I'm on the throttle after going in too hot. No sudden moves. No jumping off the throttle. Not floored. Stock FRS suspension + front crash bolts + zero toe + ESC off but no pedal dance? Mechanical variance? I dunno. My Dodge Neon came from the factory with the wrong springs. I liked to say that it was factory lowered. It was a great performer. On the road, when ESC does kick in, it's almost always in the back. The rear is EASILY upset.

Looking at the list above, clearly I'm terrible at this stuff.

The cars understeer from the factory, but are soft enough and with a low enough grip, that it's very possible to break the rear end loose before the front, whether intentional or not, causing oversteer.

A common one, is when you're understeering slightly, and abruptly lift, which transfers load to the front, and breaks the rear end loose.

[CSG Mike]

Originally Posted by ZDan

I've driven a lot of students cars over the years (not a 458!), and from general understeery stockish fwd cars to generally oversteery track-only and race cars, they all will point more IN when you get off the gas a bit, and will run wider as you get on the gas.

Remember a lot of this has to do with setup. While a setup that throttle understeers is extremely predictable, it also means the ultimate cornering potential of the car is lower. An identical car that will throttle oversteer can take an identical corner with a tighter line at a higher speed. The problem is that not everyone has the skill and/or experience to control the oversteer every time, without losing speed by allowing the slip angle to go beyond that of what the tires will tolerate.

Draw a free body diagram that illustrates the force exerted upon the car by the front and rear wheels, in a state of understeer, and in a state of oversteer. You'll note that the net forward acceleration vector of both diagrams are the same, but the net lateral acceleration vectors of the understeer car are subtractive, whereas the net lateral acceleration vectors of the oversteer car are additive. The degree of slip angle determines the net forward acceleration, and if the slip angles are identical, the forward acceleration is identical, regardless of under/over.

[juliog]

In other words

[Dembo]

Originally Posted by ZDan

AP1 reportedly gives 1/8" toe-in per inch of bump at the rear, which is a LOT! My experience with the car is that it behaves OK if you run minimal rear toe (less than ~0.3 degrees total), but the more rear toe-in you run, the more skittish and weird it gets. Unfortunately, half the S2k world INSIST on running absurd amounts of rear toe in a misguided attempt to "tame the back end". The infamous "UK alignment spec" (which I'm convinced must be based on a mistake in translating spec from degrees to arc-minutes) is for 40 arc-minutes, or 0.67 degrees! This makes the car well nigh undriveable and will wear and heat-cycle out the rears in short order, making it even *less* driveable!

I had that on mine for a while and it did make the rear feel stable, but also snappy when pushed. And because I was doing a lot of miles at the time I was buying new rear tyres every 2-3 months.

Less rear toe was a lot better once I gained the confidence to cope with it.

My biggest gripe with the GT86 is the throttle control. I'd learned to be super smooth with the S2000; feeding in the power on the exits and holding it around the limit of rear grip knowing it would respond instantly to the movements of my right foot. In this car the power comes in in a lump meaning no matter how good I am with the pedal it goes from nothing to surging forward in one instant and that means either sudden understeer or sudden power oversteer which you then have to correct. Perhaps this is what people mean when they say the transition from understeer to oversteer is too sudden.

[Frost]

Originally Posted by Dembo

In this car the power comes in in a lump meaning no matter how good I am with the pedal it goes from nothing to surging forward in one instant and that means either sudden understeer or sudden power oversteer which you then have to correct. Perhaps this is what people mean when they say the transition from understeer to oversteer is too sudden.

Funny, I hit the track with a friend who runs a BRZ and he complains about the power being not as linear as my S2k. We exchanged cars and he said mine was smoother in the powerband versus his.

And here I thought the S2k was more dual personality than the BRZ...

[Pat]

Originally Posted by CSG Mike

The FA20 is very smooth...

I'm very surprised to read that, Mike. In my experience the FA20 is one of the least smooth, buzzy engines I've driven. I've driven many cars, many of them very nice. But most of my comparison comes from owning an E28, E30, 986, B5 A4 1.8T and C5 A6 2.8 V6. I don't have nearly as much experience with domestic or Japanese four cylinder cars. Honestly, the unsmooth/buzzy nature of the FA20 is probably the thing I dislike the most about my car.
Am I alone on this?

[Capt Spaulding]

Compared to the 4cyl Japanese cars I'm acquainted with, the FA is one the smoothest. I've had a couple of Integras and spent a bit of time in my son's Civic SI and a friends 4cyl Camry. The last one would tingle just about every nerve ending I had, except, of course, the good ones. The V6s are a different story. The VQ35 in our Max was silky (until it wasn't) and the V6 in my wife's Camry is the same.

[Capt Spaulding]

I wonder if the Cayman crowd obsesses about their low oil pressure at idle.

[Pat]

Originally Posted by Capt Spaulding

Compared to the 4cyl Japanese cars I'm acquainted with, the FA is one the smoothest. I've had a couple of Integras and spent a bit of time in my son's Civic SI and a friends 4cyl Camry. The last one would tingle just about every nerve ending I had, except, of course, the good ones. The V6s are a different story. The VQ35 in our Max was silky (until it wasn't) and the V6 in my wife's Camry is the same.

Huh...interesting. I love this forum because so many people here have different experiences and perspectives than I do.
Your comment about the V6s reminded me of driving a G37XS with the VQ in it. I was appalled at how rough that was for a V6. Honestly, I thought it was garbage. Which was surprising, as I had read and heard good things about that engine.
Of course, I had been driving a 986 for a couple years at that point, so maybe it's not a fair comparison.

[CSG Mike]

Originally Posted by Pat

I'm very surprised to read that, Mike. In my experience the FA20 is one of the least smooth, buzzy engines I've driven. I've driven many cars, many of them very nice. But most of my comparison comes from owning an E28, E30, 986, B5 A4 1.8T and C5 A6 2.8 V6. I don't have nearly as much experience with domestic or Japanese four cylinder cars. Honestly, the unsmooth/buzzy nature of the FA20 is probably the thing I dislike the most about my car.
Am I alone on this?

Originally Posted by Pat

Huh...interesting. I love this forum because so many people here have different experiences and perspectives than I do.
Your comment about the V6s reminded me of driving a G37XS with the VQ in it. I was appalled at how rough that was for a V6. Honestly, I thought it was garbage. Which was surprising, as I had read and heard good things about that engine.
Of course, I had been driving a 986 for a couple years at that point, so maybe it's not a fair comparison.

Try driving a Honda I4; they're way, way rougher, but they also make more power. Keep in mind that you're also comparing "luxury" cars that attempt to isolate out the engine, to a sporty car, where NVH is intentionally retained.

The VQ is a great example. The engine was actually originally designed for maximum smoothness, but a byproduct of the design was that it actually made great power! The early variants are all buttery smooth, and the 90's and early 2000's Maximas/I30 had rave reviews for the engine. Once the VQ35DE came around, the smoothness started going away as Nissan started pursuing more power (after the gentleman's rule regarding power was breached by Honda of all companies), and the VQ37 is the end result. It makes gobs of power, but is not very smooth.

[Pat]

Yikes, I can't imagine driving a car with an engine that is "way, way rougher." No thank you.
Thanks for the perspective.