usctrojanGT3

So I'm finalizing the final aspects of my full Cayman S track build and I'm not sure which type of driver door roll cage protection I should pick. Should I get the nascar bars or the x-type like the one found in cup cars? What are the pros and cons for both? I'm looking to build the car to be PCA club racing compliant.

GT3DE

NASCAR bars way safer.

I bought a car with the X bars and immediately had them changed to NASCAR style.

stownsen914

Watch the S bends where the horizontal bars tie into the main cage .... some racing organizations will fail for that.

Scott

sbelles

I've never seen one quite like mine but I like it.

Astroman

Can somebody explain why the engineers at the Porsche factory obviously disagree with this statement?

stownsen914

Well maybe they don't ... but they might opt for the X brace because it's stiffer (for better performance). NASCAR bars are optimized for safety as the expense of stiffness. I'll take safety ...

fatbillybob

The engineers at P know exactly what they are doing. It is us and "I have done it that way forever" race shops that have to understand that you engineer a cage for "X" bars or NASCAR bars. You can't just add either because you got an A piller and a B piller to weld to. A cage is always a bag of compromises and you have to understand the consequences of the choices made.

Astroman

Why not take both?

How do you know that the X is stiffer? And by how much? Is it a significant difference?

How do you know the NASCAR style bars are "safer?" Why are they safer?

Has any of this ever actually been tested?

Astroman

I agree.

I just find it hard to believe that Porsche would knowingly sacrifice a large amount of safety for any amount of performance.

mglobe

Please explain how you know this.

LuigiVampa

I'm no race engineer (not even close) but I would hazard a guess that NASCAR bar are safer because they flare out and keep more room in between the driver and whatever is hitting the car. A car needs to absorb an impact and that usually involved things bending and crumpling somewhat. A NSACAR bar provides more of that, thus providing a greater degree of safety.

It would be nice to get some scientific evidence but I think it is pretty logical why NASCAR bars are safer.

NASCAR bars also help us "husky guys" get in an out of the cars without looking like a baby rhino being born!

J richard

As was said above a cage has to be designed as a whole system. NASCAR bars are no safer than an X bar if the cage is designed for it. The X works in tension and the NASCAR bar works in compression. Two completely different approaches. Applying NASCAR bars to a cage not designed for it is actually less safe than the X bar. Look at a NASCAR the door bars are just a section of a horizontal hoop (3 of them) that go around the cockpit to disperse the load around the shell. Weld those same bars to an unsupported main hoop or front upright and you're fooling yourself, the upright is the weak link. The x bracing is designed to transfer the load in tension between the upright and hoop, it's a more efficient use of material and lighter so no wonder Porsche does it that way.

On a practical note it has a lot to do with the doors you are going to use. Gutted factory doors allow NASCAR bars, full doors or cup style do not. I have NASCAR style bars on my boxster (tied to the sills, horizontal dash bar and horizontal in the main hoop. The cup has an override bar added to the top of the x, and the new RS build uses Xs. The boxster is the easiest to get in and out of, but in a crash with the doors closed it makes no difference at all.

flatsics

Porsche would never sacrifice safety for performance

Astroman

Ok ok. I should have specified in the modern 21st century.

stownsen914

You can certainly do both. I have seen that in fact. Racers are always worrying about weight, so I guess not many take this option.

You got me - I have not tested this. I am going only on the basic principles of triangulation and inferring that that X brace is stiffer. I'm not sure how protruding NASCAR bars (well designed of course) wouldn't be safer than an X brace sitting several inches closer to the driver, but maybe they're not. I haven't tested any of this stuff myself

To the comments about Porsche's safety choices, let's also not forget the aluminum roll cages in 935s in the 70s or the magnesium framed 917 Can AM car that almost killed Mark Donahue!