I have heard that the
Cayman
has 100% stiffer chassis than the
Boxster
and as a result it delivers more sports car feeling than the
Boxster
.
I have been wondering that what is the difference in
911
coupes and cabrios? Has anyone heard any percentage figure? I do find the
911
cabrio rigid enough, even with 19" and
PASM
in sport there is no problem even on bad road surfaces, just wondering about the figures.
In addition, does anyone know the difference between the
Boxster
and
911
cabrio? There definitely is one, but it would be nice to hear a percentage figure on this, too.
Thanks for any inputs!
From what I have read the
911 coupe
chassis is the stiffest of the group, with the
Cayman
being right behind it. Then I would say the Cab and then the
Boxster
. I don't think any one of them is anywhere near 100% stiffer than another. All of them are close if not the best in class for either coupe or convertible chassis stiffness.
If I am not mistaken the 100% between the
Boxster
and the
Cayman
has also been mentioned on this site, originally I read it in some magazine, don't remember any more which and when...
Absolutely, all of them are best in class (or so close that it makes no difference)!
EDIT: I found the 100% mentioned, in French, so my translation follows.
Grâce à son toit, le
Cayman
est 100% plus rigide que le
Boxster
et cela se ressent très bien -- Thanks to its roof, the
Cayman
is 100% more rigid than the
Boxster
and you can really feel that.
http://fr.cars.yahoo.com/essai/porsche-cayman_s_s-237-1137172001.html
What does this mean? Instead of flexing .1mm (Boxster), the Cayman chassis flexes only .05 mm? How does one measure chassis stiffness?
Logic tells us that a coupe should be stiffer than a open car because of the roof structure, all things being equal. I remember reading in Christophorus that
Porsche
used heavier body panels in the cabs than in the closed
911
's and went to great effort to make sure the drag was the same on both cars. Specifically this was on the Turbo but I would assume the engineers would be just as attentive on other models. Unless you are racing it I think the point would be moot for most of us. if I was racing it I would prefer the CS but as someone who only puts the top up in the rain or very very cold I'll sick with the
Boxster S
Basically - yes. I have read the 100% greater stiffness figure attributed to Torsional stiffness. I'm pretty sure I read it in
Porsche
literature. They also quoted a similarly impressive increase in bending stiffness.
Stiffness can be measured by physically applying a load and measuring chassis deflection. It can also be approximated by vibratory methods and FEA (finite element analysis - a computer-based calculation).
Stiff chassis will be appreciated even on the street when encountering heavy bumps. It has less obvious benefits on the track - less-stiff chassis allow greater un-damped chassis motions - stiff chassis allow greater damping and tuning at the suspension.
There is a point of diminishing returns - and there is debate about this point.
A 100% increase is doubled, so it follows then that the
Cayman
has twice the torsional rigidity of the
Boxster
? Turning it around, the
Boxster
has half of the
Cayman
's torsional rigidity? I think I need to see this stated clearly in print from an original
Porsche
source.
