IHRA and NHRA rules not including any mph limits for 1/4 mile requirements. 11.00 - 13.49 Convertibles need a 6 point roll bar. 10.00 - 11.49 All cars require a minimum 6 point roll bar. Convertibles need a full cage at 10.99 and quicker. A hardtop or T-top car can get away with only a 6 point roll bar unless the floor or firewall have been altered then a full cage is required at 10.99. 9.99 - 8.50 All cars require a full cage. 8.50 and quicker you need a 25.1D spec funny car cage. So if you have a convertible, you need a 6 point roll bar at 13.49. It's good to 11.0 then you need a full cage. If you have a hardtop or T-top car, you need a 6 point roll bar at 11.49 which is good to 10.00 as long as the floor or firewall are unmodified (most of you won't have this problem). If it has been modified then a full cage is required at 10.99 At 9.99 everyone needs a full cage. At 8.99 you need a chassis certification which will check to make sure the welds are correct and the proper size and thickness of tubing is used.

Sorry about the stupid question, but could you define a "full cage" for the 10.99 and quicker. That would be a 10 point correct?

OK, I guess the proper description should be Roll Bar and Roll Cage.

A roll bar is a main hoop behind the driver. It has 2 bars going backward and 1 but usually 2 door bars going forward. This is the typical 6 point roll bar. It can also have 2 more bars going from the main hoop down towards the driveshaft tunnel and are usually welded to the SFC if they're in that area. That makes it an 8 point roll bar.

A roll cage is any number of point configuration that also has a halo bar going around the roof and the A-piller bars. This protects the driver in a cage of tubing. Roll cages are normally anywhere from 8 to 14 points. If you run quicker than 8.50 in the 1/4 mile you need a funny car spec cage. This has extra bars surrounding the driver on both sides.

UPDATE

As of 21 Jan, IHRA has issued an update.

1/21/05
p. 97 RollCage/ Roll Bar: Delete the 4th sentence of the section stating, “T-top vehicles follow convertible guidelines.”

To me this now means T-top cars are just like before and follow hardtop rules. Roll bar at 11.99 (NHRA) and 11.49 (IHRA). Full cage at 9.99. That's assuming floor and firewall are still unmodified.

So if your car's floor and firewall are still unmodified (typical street car) then a 6 point roll bar is good to 10.00 under NHRA and IHRA rules for all cars except convertibles. If for some reason you run quicker than 135 mph and are still only in the 10 second range, you will need a full cage.

Actually Stephen there were some NHRA rule changes this winter. The roll-bar ET break is not 11.49 like the IHRA.

The list of rule changes for the NHRA can be found in this press release: http://www.nhra.com/2004/news/november/110102.html . Maybe you can make it a sticky like this post.

Trevor

Unless NHRA has updated the rules since then, I read that as IHRA and NHRA now having the same ET breaks for rollbar/cages. That makes things even easier.

Editing original message

T-top vehicles follow convertible guidelines.”

doesn't that line mean you have to follow convert. rules, not hardtop rules. That is the way my tech guy reads it anyway. Just my 2 cents worth.

Tell your tech guy to keep his rulebook updated. T-tops are not considered convertibles

As of 21 Jan, IHRA has issued an update.

1/21/05
p. 97 RollCage/ Roll Bar: Delete the 4th sentence of the section stating, “T-top vehicles follow convertible guidelines.”

Does anyone know the requirements for convertibles to run autocross in SCCA events?

Would cutting to install a manual transmission in lieu of an automatic (700r4 to a Tremec for example) be considered a modified floor? Replace the cutting with welded in sheet metal is it ok?

Also...how many cars do you know of running greater than 135 mph that are still in the 10s?

I'm getting ready to install a cage or bar and need to decide which one. Don't plan on being in the 9s anytime soon. But haven't considered the mph I may be running in near future.

9.99 and quicker in NHRA requires a cert. Maybe 8.99 for IHRA

I don't know any cars that run over 135 mph and are still in the 10's. If the car is set up properly, a 135 mph pass will be in the 9's but that doesn't mean someone has a hot street car that can get big mph but not the ET. It all depends on engine rpm range, tire size and gear ratio. If you have big HP but poor gearing (highway gears), you can cross the finish line well before your red line in high gear. You'll have a slow ET but big mph but then the gearing is all wrong.

Floor/firewall modification normally mean most of the sheetmetal has been removed and replaced with removable panels or the firewall has been cut out and moved back.

When I modified my floor/firewall I welded a new floor section back in. I run a full cage so it didn't matter. Changing the floor hump from an automatic to manual tranny but welding everything back in wouldn't be considered "modified. Normally what they're concerned with is a section of floor or firewall that can be easily removed for access to the tranny.

9.99 in NHRA requires a chassis certification.
8.99 in IHRA you need a chassis certification.

Currently I can only run at IHRA tracks because I don't have an NHRA certification nor do I have an NHRA competition license which is also required at 9.99. Competition license requires having a medical exam $, $ for license application, You need to make licensing passes and they need to be witnessed by someone else with a competition license or a certified NHRA official. You may need to pay someone or pay they're entry to the track to witness the passes.

9.99 is the magic number in NHRA. That's where everything starts to get expensive because of all the requirements at that ET. IHRA juggles the ET around for different things so it doesn't get quite as expensive until 8.50. By then it's expensive enough just to race.

Chassis certifications are somewhere in the $100-$150 range and are good for 3 years.