Rear Firewall Question

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mopowers

mopowers

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NHRA requires a rear firewall (including package tray) made of 0.024" steel or 0.032" aluminum if the battery or fuel cell is in the trunk. My question is, instead of making a one-piece sheet metal panel covering the whole package tray, can one simply cover the speaker holes.

I was thinking of making some covers for the speaker holes out of 0.032" aluminum attached with either rivets or sheet metal screws. Then I'd like to make a full size package tray out of fiber board covered in carpet to match my door panels. Would that be NHRA legal?? Have any of you guys done something similar?
 
I would sure think that would count. Especially if you welded the panels over the speaker holes. Then it's all essentially one piece.
 
I've done it that way and seen it done on many other cars. If the rear seat is retained, you still need to seal off the area behind it as well. Don't forget the smaller holes and for an added bit of safety, seal the seams. They make fire resistant caulk.
 
Locomotion said:
I've done it that way and seen it done on many other cars. If the rear seat is retained, you still need to seal off the area behind it as well. Don't forget the smaller holes and for an added bit of safety, seal the seams. They make fire resistant caulk.
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Thanks man. Do you know if the fire resistant caulk is paintable? Can you get it at the home center?
 
mopowers said:
Thanks man. Do you know if the fire resistant caulk is paintable? Can you get it at the home center?
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I've seen it in red so certain building inspectors can see the difference. But I don't know if it's paintable or comes in different colors. I've used a good regular clear caulk. Better than nothing, but I haven't seen it used regularly or that tech gets that particular.
 
mopowers said:
Thanks man. Do you know if the fire resistant caulk is paintable? Can you get it at the home center?
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I've seen clear and black as well. I'd think any home center would have it. Any place that sells wood/pellet stoves or their vent pipes will have it as well.
 
EVERY hole needs covered, defroster holes, all the small holes that are in seemingly random places. That’s why they want a full sheet.

And the rear seat area needs covered or it can catch fire and let fire inside the car.

I don’t think your patches will be accepted.

Read the rule book as to the fire resistant caulk.

Of course this depends on your tracks tech people. Some tracks don’t do much, but it’s for your safety.
 
Unless they recently changed the rules you don't need a rear firewall for the battery if you use a NHRA approved sealed battery box vented to the outside. Fuel cell in the trunk is a different story.
 
mderoy340 said:
Unless they recently changed the rules you don't need a rear firewall for the battery if you use a NHRA approved sealed battery box vented to the outside. Fuel cell in the trunk is a different story.
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^^THIS^^ I have a Moroso I think. Damn thing is heavy. It has to be that to contain a battery explosion
 
mderoy340 said:
Unless they recently changed the rules you don't need a rear firewall for the battery if you use a NHRA approved sealed battery box vented to the outside. Fuel cell in the trunk is a different story.
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You are correct. My car's got a trunk-mounted fuel cell though, so I'll need a rear firewall regardless.

I'm going to shoot an email to our NHRA division tech director. I'll let you all know what he says.
 
413 said:
EVERY hole needs covered, defroster holes, all the small holes that are in seemingly random places. That’s why they want a full sheet.

And the rear seat area needs covered or it can catch fire and let fire inside the car.

I don’t think your patches will be accepted.

Read the rule book as to the fire resistant caulk.

Of course this depends on your tracks tech people. Some tracks don’t do much, but it’s for your safety.
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I don't have a rear seat and plan on using a full sheet of .040 aluminum for the main rear bulkhead/seat back area (riveted around the perimeter and to the seat bracing), then I'll cover it with a sheet of carpeted fiberboard. Though, I may just spray it with some truck bed coating or something similar

The only holes in my package tray are the 3 speaker holes and the elongated rear defroster slot. I'll also be covering the areas of the C-pillar that are open to the trunk area.

Here are some excerpts from the NHRA rulebook (below). I don't see anything that specifically prohibits covering individual holes vs using a full sheet. Now that I think of it, I'm not sure what the difference would be from someone screwing on a cover for a deleted heater blow motor or something similar on the front firewall. I will double check with our tech guy though. Luckily he's very responsive to these types of rule questions via email. Thanks guys.

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If the speaker holes are the only holes, I think that would be legal.
I made two 1/16 panels (materials I had) for the package shelf and firewall, and covered them with thin light indoor/outdoor.
 
33IMP said:
If the speaker holes are the only holes, I think that would be legal.
I made two 1/16 panels (materials I had) for the package shelf and firewall, and covered them with thin light indoor/outdoor.
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Do you have any photos of yours that you'd be willing to share?
 
I covered all the holes in my car with tin that I screwed to the original panels. No problem at NHRA or IHRA tracks. One thing is that the top of your fuel call can’t be higher than the top of your tires. Kim
 
oldkimmer said:
I covered all the holes in my car with tin that I screwed to the original panels. No problem at NHRA or IHRA tracks. One thing is that the top of your fuel call can’t be higher than the top of your tires. Kim
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mopowers said:
Is that in the NHRA rulebook? I can't find anything that states that. I'm pretty sure that's not an issue in my car though.
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Thats news to me. I'm pretty sure one of mine was higher than the tires, but no tech guy ever gave me any grief.
 
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