Clutches, scattershields, and the $20XX Challenge meet the NHRA

I need a little help sorting through the NHRA safety rules for manual shift cars. Bottom line, as I am reading it, it would be nearly impossible to build a fast manual shift car under Challenge budget.

I'd really like a manual, but the rules (and generally safety) may prohibit what I am trying to do.

The car is a mid engine RWD car- engine in the transverse position. The engine will be swapped to a supercharged V6. Transmission is original. Flywheel is custom (but not necessarily to the SFI spec). Nitrous is a consideration. Trying to build to run deep 11's.

So, here are my questions:

• It appears to me that ALL OEM stock-type cast iron flywheels and/or pressure plates are prohibited, regardless of speed. Wouldn't this prohibit stock manual cars from running?? Does this mean most manual shift Challenge cars are illegal for the NHRA?

• All supercharged vehicles with an aftermarket planetary transmission require a flywheel shield. Does this apply to stock manual transmissions?

• All cars running 11.99 or faster must have an after market clutch, flywheel, and flywheel shield. Is this possible on a Challenge budget?

• Some engines for which adapter shield is not commercially available, permit a flywheel shield made of 1/4-inch mounted to the frame completely surrounding the bellhousing 360 degrees. How would I know which engines? (I am assuming this is one).

With the engine in the transverse position behind the driver, unfortunately the potential risk of a blown-up flywheel could be a LOT worse than cutting off my legs, so I am trying to do this right.

Thoughts? Do I need to switch to an auto? Limit my ET to 12.00? Build a custom shield? Anyone have any diagrams, links, or pictures? Do the rules simply push this over reasonable budget considerations?

Thanks for your help.

SVreX wrote: - It appears to me that ALL OEM stock-type cast iron flywheels and/or pressure plates are prohibited, regardless of speed. Wouldn't this prohibit stock manual cars from running?? Does this mean most manual shift Challenge cars are illegal for the NHRA?

Sounds like it...

- All supercharged vehicles with an aftermarket planetary transmission require a flywheel shield. Does this apply to stock manual transmissions?

Aftermarket planetary transmission = Lenco. If you can do a Lenco on a Challenge budget, I want to see it!

- All cars running 11.99 or faster must have an after market clutch, flywheel, and flywheel shield. Is this possible on a Challenge budget?

Probably not. Any modification removes the SFI rating.

- Some engines for which adapter shield is not commercially available, permit a flywheel shield made of 1/4-inch mounted to the frame completely surrounding the bellhousing 360 degrees. How would I know which engines? (I am assuming this is one).

Contact the SFI and see if they have certified any, would be my guess.

Aren't there factory OEM cars exceeding 11.9 with stick shift manual gearboxes?

I know they aren't anywhere near challenge price yet, but it may have some bearing on this discussion.

Edit:a couple seconds on Google suggests that a C6 can do it.

In reply to HappyAndy:

You can get a Hellcat with a stick, right?

HappyAndy wrote: Aren't there factory OEM cars exceeding 11.9 with stick shift manual gearboxes? I know they aren't anywhere near challenge price yet, but it may have some bearing on this discussion. Edit:a couple seconds on Google suggests that a C6 can do it.

Well, that is partly my question. I'm not so good at speaking NHRA, but I'm just offering what my understanding is based on a cursory reading. I don't think it is written very well, but it sure appears like it would rule out OEM setups.

But you don't have to go 11.99 to rule them out. The prohibition against cast iron flywheels would rule out everything, even if it is running 24 second 1/4 miles.

Knurled wrote:

- All supercharged vehicles with an aftermarket planetary transmission require a flywheel shield. Does this apply to stock manual transmissions?

Aftermarket planetary transmission = Lenco. If you can do a Lenco on a Challenge budget, I want to see it!

I think you missed my point. There is no reference to an OEM manual transmission. Only to an automatic, and an after market planetary. Which seems to imply a stock trans is fine with no flywheel shield regardless of the speed or power. I don't think that's what they meant either.

I thought safety equipment does not count toward your budget.

No, that's not true.

Only certain SPECIFIED safety equipment is budget exempt. That does not include flywheels, clutches, or scattershields.

This brings up one of my concerns about the safety rules for 2017. I believe someone once mentioned that there's only one battery box certified by NHRA and SCCA. Obviously we want to be safe but it seems like the Challenge needs wiggle room. More of a common sense interpretation of the NHRA/SCCA safety rules.

Or roll bars, IE cages. Now Ya'll Lookie Hear, We got this old shopping center what's closed down, Easy 1/4 mile straight and lots a room for a course round the parkin' lot, We don't need no stinking rules. So Bad Joke but if you can do the number you shouldn't have to Pay for it........ Kinda!

Stampie wrote: This brings up one of my concerns about the safety rules for 2017. I believe someone once mentioned that there's only one battery box certified by NHRA and SCCA. Obviously we want to be safe but it seems like the Challenge needs wiggle room. More of a common sense interpretation of the NHRA/SCCA safety rules.

I believe that was me.

What I said was there was only 1 battery box approved by BOTH NHRA and SCCA.

But, that assumes a battery box. There are other ways.

HappyAndy wrote: Aren't there factory OEM cars exceeding 11.9 with stick shift manual gearboxes? I know they aren't anywhere near challenge price yet, but it may have some bearing on this discussion. Edit:a couple seconds on Google suggests that a C6 can do it.

I also believe that convertibles faster than 13.99 require a rollbar.

What modern convertibles CAN'T run 13.99?

Stampie wrote: This brings up one of my concerns about the safety rules for 2017. I believe someone once mentioned that there's only one battery box certified by NHRA and SCCA. Obviously we want to be safe but it seems like the Challenge needs wiggle room. More of a common sense interpretation of the NHRA/SCCA safety rules.

There's a certified box?

I thought all you needed to make the NHRA happy was a minimum of two 3/8" fasteners holding the battery to the structure of the car.

This is why I use 3/8" all-thread to make battery mounts, as that counts as "accepted best practice".

Of course, there are about three zillion cars on the road now with the battery in the cabin or trunk, with the battery held down with one (1) 8mm or even 6mm bolt.

I haven't looked at an NHRA rulebook for over a decade, but it used to be that you only needed an SFI bellhousing and billet flywheel if running a solid lifter camshaft or quicker than a certain et..

Knurled wrote:

HappyAndy wrote: Aren't there factory OEM cars exceeding 11.9 with stick shift manual gearboxes? I know they aren't anywhere near challenge price yet, but it may have some bearing on this discussion. Edit:a couple seconds on Google suggests that a C6 can do it.

I also believe that convertibles faster than 13.99 require a rollbar. What modern convertibles CAN'T run 13.99?

You guys are missing one important phrase.

...convertibles faster than 13.99 require a rollbar when competing in an NHRA event. They'll also require rollbars to go to most track days.

The bellhousing used to be exempt until it got exploited by a certain BMW from Texas. When I inquired about the rule being reinstated, I was flatly told, "No.".

Now, I wouldn't mind the SFI rated equipment have to to challenge budgeted at something like twice the OE available price.

Knurled wrote:

HappyAndy wrote: Aren't there factory OEM cars exceeding 11.9 with stick shift manual gearboxes? I know they aren't anywhere near challenge price yet, but it may have some bearing on this discussion. Edit:a couple seconds on Google suggests that a C6 can do it.

I also believe that convertibles faster than 13.99 require a rollbar. What modern convertibles CAN'T run 13.99?

Stock ND Miatas? :)

From my recollection the firewall counts as a scattershield for a FWD or transverse mid-engine car, assuming it remains unaltered.

In reply to drdisque:

That makes as much sense as claiming the floor counts as a scattershield.

Yeah, the firewall should be able to stop that.

This is as subject I kind of think about a bunch. I've had one clutch come apart, thankfully at low RPM. Was able to drive it home but the off center weight distribution made the car shake violently over 3000, and at the time I was shifting at 7700. Wonder if it would have "disassembled" if the clutch came apart that high up. Nowadays, 7700 is closer to what the revs DROP to after a shift.

https://www.youtube.com/embed/9Cjy384t47Y

Note clutch smoke at the 2-4 second mark when the tires stop spinning and he does a "clutch burnout".

Some people joke about weak clutches as being easy on drivetrain parts, I see it as adding a lot of heat to an area where a lot of heat would be a bad idea.

drdisque wrote: From my recollection the firewall counts as a scattershield for a FWD or transverse mid-engine car, assuming it remains unaltered.

That would help. Any reference?