Cayman 2.7 PASM6 Sport Chrono 230km perspectives

[centurion]

Re: Cayman 2.7 PASM6 Sport Chrono 230km perspectives

Here's something on PASM. Think it's realtime. Not infinite though, but PASM is keyed to damper speed, not body roll angle. Therefore, I think it fulfils your requirement of realtime adjustment.

The Cayman Club - FAQ: Cayman Options

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Porsche Active Suspension Management (PASM) electronically controls the performance of the shock absorbers. By continuously adjusting the damping force in each shock, PASM balances the conflicting agendas of ride and handling. Regardless of road surface or driving style, PASM preserves the Boxster’s natural agility while enhancing its ride comfort. With PASM, sharp and smooth are no longer mutually exclusive features.
Available as an option on both Boxster models, PASM is also part of the optional Sport Package, along with a high-performance, six-speed manual gearbox (2.7-liter Boxster only). Equipped with PASM, the car rides 10mm lower than with the standard suspension. PASM has two setup modes: “Normal” and “Sport.” While the former offers a blend of performance and comfort, the Sport setup ratings are generally much firmer. In either mode, PASM reacts to changes in the road and driving style by applying a variable, map-based damping force on each individual wheel.
During acceleration, braking and cornering maneuvers, a series of sensors monitors the body. A dedicated control unit provides real-time analysis and damping force adjustment as defined for the respective setup mode (Normal or Sport). You can feel the results: greater stability on poor road surfaces as well as more consistent occupant comfort.
If Sport mode is selected, the suspension is set to a harder damping force. If the quality of road surface drops below a certain threshold, PASM changes to a softer rating within the Sport setup band to help preserve the car’s grip and traction. When the road surface improves, PASM returns to the original, stiffer rating.
The system remains active in Normal mode, too, automatically switching to a harder force if the car is driven more assertively. As the shock absorbers become stiffer, the Boxster becomes more stable, matching more aggressive driver inputs with a firm and authoritative response.

 

[Shaun]

Re: Cayman 2.7 PASM6 Sport Chrono 230km perspectives

I realize PASM is keyed to shock velocity, but I was discussing how it could or couldn't be used to limit roll angle except in shorter turns, after you mentioned flat cornering in your first post.

The posted graph only shows force-velocity range of adjustment in bound. It doesn't show reaction speed. The text doesn't mention it either. If there are numbers or graphs on reaction speed then you can figure out whether it can react to the very first bump it encounters, and at exactly what speed for a given bump profile.

Sidenote on graph is what a better driver may very well lap quicker in normal vs sport mode in anything over 1 or 2 laps, since he does not require the low shaft speed support and feedback to drive quick. Really good drivers are able to drive almost completely linear damping curves with very little low speed damping. There are other factors like tire type, and suspension geometry, etc. but that is the trend especially in full weight street tired under tired cars in hot climates, that don't need extra energy input to the tire to get it up to temp, or more often are over heated out on track. For everyday sport driving in spurts though, support feels good.

 

[acupunch]

Re: Cayman 2.7 PASM6 Sport Chrono 230km perspectives

was heading to car washed at the SPC opposite, I saw a white cayman at HURRY TIRES during SAT morning. its that u? choosing your rims?

 

[centurion]

Re: Cayman 2.7 PASM6 Sport Chrono 230km perspectives

Shaun, your post illuminates! However, if the velocity of the shaft is fast and then the damping force almost immediately increases, then using this way the car can flatten. But yes, I know that by controlling 2 small little holes you can't really have instantaneous response, perhaps in 0.1 seconds later which we already have more travel.... aiyah this is way beyond me.

Suffice to say for casual driving it is flat, but racing drivers have criticized the stock cayman suspension as somewhat soft, but of course these are ALMS drivers so they're used to their Corvettes and RSRs.

Acupunch, these few days the only time I have to go for a spirited drive is after 10pm, besides my daily driving commute. I am trying to sync myself with the clutch now, so training my downshift rev matching to smoothness. This transmission is not so easy to master like the Honda's but it is rewarding. VERY rewarding.

So it's not me. The White Cayman you see is another guy .... I think he got SGX numberplate or something. If so, that's the demo car which was bought at list price by some guy so smitten by the Cayman after the test drive that he immediately sign cheque. Tippy, so that's not mine.

 

[Shaun]

Re: Cayman 2.7 PASM6 Sport Chrono 230km perspectives

Yes low damping forces at low shaft speeds will allow slightly higher shaft speeds, but only very slightly relative to a good sized at speed because the forces involved are very different in magnitude. For a street car to exceed 1 G lateral is an accomplishment, whereas to experience vertical wheel accelerations in the range of 3-5 G, from bumps, shaft speeds anywhere around 15 inches/sec is not surprising. Also to reach high enough shaft speeds you need enough time at a given accel. At the very extreme you have rally cars that can’t pull even 1 G lateral, but run up to ~50 G vertical wheel accelerations and 400 inches/sec shaft speeds - incredible overall shaft speed range. Neither one can corner flat – especially not a rally car. Closing bleeds can limit roll, but requires backup valves (and very progressive ones if the reaction to bump is to be remotely smooth) to deal with bumps in corner and once brought into action, can no longer limit roll for the remainder of the turn. Shrinking down bleed areas till roll occurs very slowly does not limit roll angle, only takes more time for it to get there, and there are still the same bump issues as with totally closed bleeds.

 

[BlacTT]

Re: Cayman 2.7 PASM6 Sport Chrono 230km perspectives

was heading to car washed at the SPC opposite, I saw a white cayman at HURRY TIRES during SAT morning. its that u? choosing your rims?

So it's not me. The White Cayman you see is another guy .... I think he got SGX numberplate or something. If so, that's the demo car which was bought at list price by some guy so smitten by the Cayman after the test drive that he immediately sign cheque. Tippy, so that's not mine.

Hi, my first post here. Great forum you have here.

/acupunch: That would be my CS. Went to Hurry to swap my stock CSC2 to PS2.

/caySman: Don't think there's a white demo CS and certainly didn't pay list price for it.