Cage requirements

So, im having a mental debate. 

Darth nader needs some form of cage. Thats a given.

However, the number of points are in question. 

The chassis, floors, and firewall are from a 2000 corvette. 

The body is from a 1962 corvair.

Everything has been altered in bigger or smaller ways to mate the two. 

The car will be capable of 10s in the quarter (hopefully)

Hiw much cage do we need? I dont want more cage than necessary. Id like to get away with a 6 point, but i think i will have to have an 8 or 10 for the reasons of modified firewall. Main reasons i want less cage is for cost/weight/streetability.

I imagine the NHRA rule book has your answer somewhere inside it. 

In reply to mazdeuce - Seth :

I am absolutely sure it does. However it is ambiguous on something like this in my understanding. The main reason for this thread. I can't quite seem to make out just what they want.

Anything anyone posts here is going to be their *interpretation* of the rules, unless they are an NHRA Tech Inspector.

This NHRA Quick Reference Chart 

This NHRA quick reference chart breaks down required safety equipment by ET and in some cases MPH within an ET range.

I'll tell you how *i* read it, but you'd be best served by calling your regional NHRA Tech Inspector.  Good luck finding out who that is and how to contact them, as I have no suggestions there and i'm likely the smartest person you know.

the top of the first section tells you how to decode the symbols numbers etc.

so it says that Roll Bars in compliance with general reg 4:10 are allowable in any car all the way down to 10.00 ET / up to 135 mph, but are *required* in Convertibles running 13.49 and quicker, and also are required in non-Convertibles running 11.49 and quicker.

in the very next line it says that Roll Cages in compliance with general reg 4:11 are allowable in any car but are *required* in all cars quicker than 9.99_OR_faster than 135 mph.

General Reg 4:10 describes and illustrates a legal roll bar in terms of materials, dimensions, and attachment points.

General Reg 4:11 describes but does not illustrate a legal roll *cage* in terms of materials, dimensions, and attachment points.

4:10 defines attachment of roll bar for "...cars with an OEM frame..." as well as for "cars without frame" ie unibody.  this rule does not specify or require that the OEM frame has to be OEM _for_that_car_.  In your case, you have an OEM Corvette frame inside a Corvair car that was a unibody but no longer has OE structure, so my interpretation is that you'd follow the OEM frame attachment method.  In my case, since I've retained the Corvair unibody structure, i would follow the "without a frame" attachment method.

I read it much like angry. Faster than 10 needs the cage. And I think at that level the cage rules might be tied to the "class" you're running. I.e. sportsman, modified, altered, etc.

In general the nhra bar will need to be thicker than scca bar, and they have different requirements. We had a thread on that maybe a year or so back.

here's what the NHRA General Reg 4:11 says about modified firewalls:

So, the way *i* read that, is if Darth is quick and/or fast enough to require a Roll Cage according to 4:11, you will have to include a "lower windshield or dash bar" as defined in the blue highlighted area above.

My fantasy cage is an overbuilt 8 point. Which, the way i interpret it, is what we have to do. And ut sounds like you all read it the same way.

The dash bar would only be applicable if the car needs a full cage per the rules, vs just a roll bar. If the planned ET is 10.0 or greater (rwd better be under 135) and has a roof, just the std 5/6 pt is necessary. If you want to build in a better cage that is totally acceptable as well, but to get it certified needs all the right bits and pieces (including d bars/tunnel bar, dash bar if needed). 

I think a normal roll bar would be plenty for this car. 

10 pts. Just like the generic jegs cage picture is in the catalog.

It depends on if it's a c5 with unmodified passenger compartment and firewall and extensive body mods or a corvair with everything modified.  I was going to go with an 8 point bar and argue the former if pressed.

Patrick said:

It depends on if it's a c5 with unmodified passenger compartment and firewall and extensive body mods or a corvair with everything modified.  I was going to go with an 8 point bar and argue the former if pressed.

This is the key. I have a full SCCA roll cage in my truck, and when thinking about what it would run on the dragstrip vs what NHRA requires at that ET/MPH I am probably fine in arguing that my 1.5" 4130 roll cage will pass tech in place of NHRAs roll bar requirement. That means 10.0 or slower, but wait, I have a modded firewall, make that 11.0, and it's still going to be dependent on the mood of the track inspector each night....

Find the contact info for the local NHRA cage inspector and get his input. Better safe than on the trailer.