In light of recent events.

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Big Thumper said:
Ok, here's the breaks as I understand them from the NHRA rulebook.

11.49 to 10.00 - 5 pt. rollbar required. Max car weight = ? I'm going to use 4750 here, from Greg's earlier note about the max weight allowed for a sub-10 sec NHRA cage. (They allow a 5 pt rollbar in cars between 11.5 and 10.0 as long as the body / firewall / frame is stock and complete.)

135+ OR 9.99 and quicker = NHRA 8 pt cage, up to 8.50 ET (around 160 MPH). NHRA 3-year certification tag required, max weight 4750.

8.49 and down (161+) requires an SFI 25.5 spec cage, max weight 3600.

So, we've got 'stages' of required in-cab protection as follows, based on a kinetic energy threshold.

Rollbar required at anything over: 11.49 ET (Approximately 118 MPH) @ 4750 lbs.
Equivalent KE: 71,136,162 lb-ft

NHRA 8pt Cage required at anything over: 9.99 ET OR 135 MPH @ 4750 lbs.
Equivalent KE: 93,109,492 lb-ft

SFI 25.5 Cage required at anything over: 8.50 ET (Approximately 161 MPH) @ max 3600 lbs.
Equivalent KE: 1,000,000,000 lb-ft

If you notice, there's a couple gaps - if a 4750 lb car is running 8.51 @ 160 MPH, it's going to be packing a lot more KE (1.31 bill. lb-ft) into it's NHRA 8pt cage than a 2800 lb Pro Stock Truck running 174 with an SFI full chassis (0.91 bill. lb-ft).

In reality, there aren't any 4750 lb cars running those speeds. BUT, the SAME ENERGY (1,310,000,000 lb-ft) is generated by an 8000 lb truck running just 123 MPH.

The atttached graph tries to illustrate these 'breaks' or brackets, using a given kinetic energy as a dividing line.

The white area is the equivalent of running sub-118 MPH @ 4750 lbs - kinetic energy at or under 0.71 billion lb-ft. Notice it's capped at 118 - any MPH over that will put you under 11.49, the break for requiring at least a bar. Notice how it drops as weight increases to the right. An 8000lb truck generates enough KE to need at least a bar by 91 MPH.

The green area is the 'Roll Bar' zone, with kinetic energies between 0.71 and 0.93 billion lb-ft. Notice it's also capped at 135 on the left - that's the NHRA breakpoint for needing a full 8-point cage.

The yellow area is the '8 Point Cage' zone, with kinetic energies between 0.93 and 1.31 billion lb-ft. Notice the sloped dash line - that's the KE line for a 3600lb car @ 161 MPH (8.50 ET). I didn't use that as the upper limit for the 'cage' area because of what I mentioned above - the mythical 4750 lb car running 8.51 @ 160, legally. That car's equivalent KE line is the upper boundary of the 'cage' area.

Anything in red crosses over into SFI territory - and there's nothing that's really representative, as their chassis specs are capped (currently) at 3600 lbs.

So, what can we take from the graph?

8000 lb trucks running between 91 - 104 MPH need a bar. 104 to 123 needs an 8 point, NHRA certified cage. Over 123 and the basic NHRA 8pt cage likely won't cut it.

6000 lb trucks running between 105 and 120 need a bar. 120 to 142 needs aan 8 point, NHRA certified cage. Over 142 and the basic NHRA 8pt cage likely won't cut it.

And so on, by weight.

Attached a table with values every 500 lbs, so you can see where your rig fits in.

So, back on topic: for guys running sub-11.5 (call it faster that 120 MPH): If the truck weights more than 6000 lbs, it needs a full 8 point NHRA certified cage to be on par with their current rules / weight limits, regarding equivalent, worst-case kinetic energy. (4750 lbs @ 135 MPH = 6000 lbs @ 120 MPH).

Ref: http://www.nhra.com/contacts/tech_faq.html
Click to expand...


as it should be for everyone entered in the race..thats only the beginning of safety fellas..get a grip on it
 
Big Thumper said:
Ok, here's the breaks as I understand them from the NHRA rulebook.

11.49 to 10.00 - 5 pt. rollbar required. Max car weight = ? I'm going to use 4750 here, from Greg's earlier note about the max weight allowed for a sub-10 sec NHRA cage. (They allow a 5 pt rollbar in cars between 11.5 and 10.0 as long as the body / firewall / frame is stock and complete.)

135+ OR 9.99 and quicker = NHRA 8 pt cage, up to 8.50 ET (around 160 MPH). NHRA 3-year certification tag required, max weight 4750.

8.49 and down (161+) requires an SFI 25.5 spec cage, max weight 3600.

So, we've got 'stages' of required in-cab protection as follows, based on a kinetic energy threshold.

Rollbar required at anything over: 11.49 ET (Approximately 118 MPH) @ 4750 lbs.
Equivalent KE: 71,136,162 lb-ft

NHRA 8pt Cage required at anything over: 9.99 ET OR 135 MPH @ 4750 lbs.
Equivalent KE: 93,109,492 lb-ft

SFI 25.5 Cage required at anything over: 8.50 ET (Approximately 161 MPH) @ max 3600 lbs.
Equivalent KE: 1,000,000,000 lb-ft

If you notice, there's a couple gaps - if a 4750 lb car is running 8.51 @ 160 MPH, it's going to be packing a lot more KE (1.31 bill. lb-ft) into it's NHRA 8pt cage than a 2800 lb Pro Stock Truck running 174 with an SFI full chassis (0.91 bill. lb-ft).

In reality, there aren't any 4750 lb cars running those speeds. BUT, the SAME ENERGY (1,310,000,000 lb-ft) is generated by an 8000 lb truck running just 123 MPH.

The atttached graph tries to illustrate these 'breaks' or brackets, using a given kinetic energy as a dividing line.

The white area is the equivalent of running sub-118 MPH @ 4750 lbs - kinetic energy at or under 0.71 billion lb-ft. Notice it's capped at 118 - any MPH over that will put you under 11.49, the break for requiring at least a bar. Notice how it drops as weight increases to the right. An 8000lb truck generates enough KE to need at least a bar by 91 MPH.

The green area is the 'Roll Bar' zone, with kinetic energies between 0.71 and 0.93 billion lb-ft. Notice it's also capped at 135 on the left - that's the NHRA breakpoint for needing a full 8-point cage.

The yellow area is the '8 Point Cage' zone, with kinetic energies between 0.93 and 1.31 billion lb-ft. Notice the sloped dash line - that's the KE line for a 3600lb car @ 161 MPH (8.50 ET). I didn't use that as the upper limit for the 'cage' area because of what I mentioned above - the mythical 4750 lb car running 8.51 @ 160, legally. That car's equivalent KE line is the upper boundary of the 'cage' area.

Anything in red crosses over into SFI territory - and there's nothing that's really representative, as their chassis specs are capped (currently) at 3600 lbs.

So, what can we take from the graph?

8000 lb trucks running between 91 - 104 MPH need a bar. 104 to 123 needs an 8 point, NHRA certified cage. Over 123 and the basic NHRA 8pt cage likely won't cut it.

6000 lb trucks running between 105 and 120 need a bar. 120 to 142 needs aan 8 point, NHRA certified cage. Over 142 and the basic NHRA 8pt cage likely won't cut it.

And so on, by weight.

Attached a table with values every 500 lbs, so you can see where your rig fits in.

So, back on topic: for guys running sub-11.5 (call it faster that 120 MPH): If the truck weights more than 6000 lbs, it needs a full 8 point NHRA certified cage to be on par with their current rules / weight limits, regarding equivalent, worst-case kinetic energy. (4750 lbs @ 135 MPH = 6000 lbs @ 120 MPH).

Ref: http://www.nhra.com/contacts/tech_faq.html
Click to expand...

WOW , Great work , I can not even fathem 330 mph in a 2550 funny car .
 
Big Thumper said:
Ok, here's the breaks as I understand them from the NHRA rulebook.

11.49 to 10.00 - 5 pt. rollbar required. Max car weight = ? I'm going to use 4750 here, from Greg's earlier note about the max weight allowed for a sub-10 sec NHRA cage. (They allow a 5 pt rollbar in cars between 11.5 and 10.0 as long as the body / firewall / frame is stock and complete.)

135+ OR 9.99 and quicker = NHRA 8 pt cage, up to 8.50 ET (around 160 MPH). NHRA 3-year certification tag required, max weight 4750.

8.49 and down (161+) requires an SFI 25.5 spec cage, max weight 3600.

So, we've got 'stages' of required in-cab protection as follows, based on a kinetic energy threshold.

Rollbar required at anything over: 11.49 ET (Approximately 118 MPH) @ 4750 lbs.
Equivalent KE: 71,136,162 lb-ft

NHRA 8pt Cage required at anything over: 9.99 ET OR 135 MPH @ 4750 lbs.
Equivalent KE: 93,109,492 lb-ft

SFI 25.5 Cage required at anything over: 8.50 ET (Approximately 161 MPH) @ max 3600 lbs.
Equivalent KE: 1,000,000,000 lb-ft

If you notice, there's a couple gaps - if a 4750 lb car is running 8.51 @ 160 MPH, it's going to be packing a lot more KE (1.31 bill. lb-ft) into it's NHRA 8pt cage than a 2800 lb Pro Stock Truck running 174 with an SFI full chassis (0.91 bill. lb-ft).

In reality, there aren't any 4750 lb cars running those speeds. BUT, the SAME ENERGY (1,310,000,000 lb-ft) is generated by an 8000 lb truck running just 123 MPH.

The atttached graph tries to illustrate these 'breaks' or brackets, using a given kinetic energy as a dividing line.

The white area is the equivalent of running sub-118 MPH @ 4750 lbs - kinetic energy at or under 0.71 billion lb-ft. Notice it's capped at 118 - any MPH over that will put you under 11.49, the break for requiring at least a bar. Notice how it drops as weight increases to the right. An 8000lb truck generates enough KE to need at least a bar by 91 MPH.

The green area is the 'Roll Bar' zone, with kinetic energies between 0.71 and 0.93 billion lb-ft. Notice it's also capped at 135 on the left - that's the NHRA breakpoint for needing a full 8-point cage.

The yellow area is the '8 Point Cage' zone, with kinetic energies between 0.93 and 1.31 billion lb-ft. Notice the sloped dash line - that's the KE line for a 3600lb car @ 161 MPH (8.50 ET). I didn't use that as the upper limit for the 'cage' area because of what I mentioned above - the mythical 4750 lb car running 8.51 @ 160, legally. That car's equivalent KE line is the upper boundary of the 'cage' area.

Anything in red crosses over into SFI territory - and there's nothing that's really representative, as their chassis specs are capped (currently) at 3600 lbs.

So, what can we take from the graph?

8000 lb trucks running between 91 - 104 MPH need a bar. 104 to 123 needs an 8 point, NHRA certified cage. Over 123 and the basic NHRA 8pt cage likely won't cut it.

6000 lb trucks running between 105 and 120 need a bar. 120 to 142 needs aan 8 point, NHRA certified cage. Over 142 and the basic NHRA 8pt cage likely won't cut it.

And so on, by weight.

Attached a table with values every 500 lbs, so you can see where your rig fits in.

So, back on topic: for guys running sub-11.5 (call it faster that 120 MPH): If the truck weights more than 6000 lbs, it needs a full 8 point NHRA certified cage to be on par with their current rules / weight limits, regarding equivalent, worst-case kinetic energy. (4750 lbs @ 135 MPH = 6000 lbs @ 120 MPH).

Ref: http://www.nhra.com/contacts/tech_faq.html
Click to expand...


Great work Matt, I think we can all learn from this!
 
TMONEYDIESEL said:
Wow that was deep but i agree, the safer the better accidents are going to happen anyway whether it be a slick track or a mechanical malfunction we need to be prepared as best as possible,
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That's exactly what I'm saying, we don't know what these trucks can handle in a hard roll over. I'm not calling for a major rule change. I just think someone with experience needs to look at the weight and speeds and "do the math" to determine if the guide lines that the NHRA and IHRA have set are enough.
 
THATpreston said:
There are NO standards for rollover strengths. Looking at the pillar sizes on my 3500 versus other vehicles, I don't see much difference.
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I'll have to double check for my self, but I think there is a basic standard that may not be official. You can't expect the pillar design of a focus to stand up on a F350 can you? They do it internally, but don't need to. lemme ask and google around and show ya some stuff.
 
JasonCzerak said:
I'll have to double check for my self, but I think there is a basic standard that may not be official. You can't expect the pillar design of a focus to stand up on a F350 can you? They do it internally, but don't need to. lemme ask and google around and show ya some stuff.
Click to expand...

EVery rolled over super duty ive seen has a pancaked roof. Fords are NOT safe in rollovers. Dodge's and GM's hold up significantly better, but their roofs do still yield (give in) a little bit under the weight.

These new rules are rediculous. The LBZ and LMM duramax's are FAST stock, like 15 flat. I dont know mph, but with these rules, you are saying that a 200 dollar SUPERCHIPS could put an LBZ in rollbar territory? Get real.
 
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duratothemax said:
These new rules are rediculous. The LBZ and LMM duramax's are FAST stock, like 15 flat. I dont know mph, but with these rules, you are saying that a 200 dollar SUPERCHIPS could put an LBZ in rollbar territory? Get real.
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Nobody has changed a single rule. We are(were) talking about hypothetical situations here.

I'll add this too:

Nobody is trying to make any rules behind closed doors, put bars in trucks that don't need to be there, or force anyone to race on the street. At one point in this thread, we were talking about safety if 11.50 trucks and quicker. That has turned into safety for God knows what.

I'm going to make one more attempt to right the ship here.


KEEP DISCUSSION LIMITED TO 11.50 (where the current Roll Bar rule is) AND QUICKER.
 
We have not discussed qualified drivers yet. Seems anyone can stick a killer engine in anything they want and make a pass down the strip and no questions asked wether they ever drove anything that fast before. After watching the video of the crash it looked like he hit the throttle just before he went through the guard rail. Either his body was not strapped down or he panicked.
 
Somebody touched on it a bit earlier but it never got much play between the claims of forcing people to race on the street and rollbars in 16 second trucks but, NHRA does not require a license until 9.99 or quicker.
 
Heres a crazy thought, If you don't drive or plan to drive an 11.50 truck, then don't post, as its not going to pertain to you. Perhaps you guys can start a thread for safety of trucks 11.50 and over.
 
Thank you Matt for running these calculations. I think they are interesting, but we need to keep in mind that there is more to occupant safety than just kinetic energy. Presumably SFI conducts dynamic simulations and finite element analysis in developing the standards that already exist. I know I did in my prior life developing frames and occupant protection structures for lift trucks. One possibly difficult aspect would be coming up with accurate solid models of existing cabs and frames. As many in the aftermarket industry are aware, getting anything from the Big 3 beyond the files posted with SEMA is a major challenge. The possibility of these files being used against them in a lawsuit is enough of a deterrent to disseminating them, but perhaps an association like SFI can obtain them.

David Dunbar (assuming you haven't fallen asleep reading this thread), can you please chime in on whether these things are being considered by SFI?

Thanks,
Michael Pliska
 
LOGANSTANFORTH said:
im sure Gary heard alot of crap about spending all that money on that truck from his wife like all men do, but im pretty sure there will be no arguing EVER over the cost of a safety item from anyones wife on here after this.....
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I am Gary's wife and I would like everyone to know I was there with him at the race. I know alot men do get crap about the money, but I love him to much to give him up because I was cheap. But the truck he race's I am behind him all the way with safety. I love racing just as much as he does, so if he needs the money--go for it. Money comes and goes, but I can't replace him.

Loretta:thankyou2: *nx*
 
mswrongway said:
I am Gary's wife and I would like everyone to know I was there with him at the race. I know alot men do get crap about the money, but I love him to much to give him up because I was cheap. But the truck he race's I am behind him all the way with safety. I love racing just as much as he does, so if he needs the money--go for it. Money comes and goes, but I can't replace him.

Loretta:thankyou2: *nx*
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Hey Loretta! Hope all is well with you, Look forward to seeing you guys soon!
 
mswrongway said:
I am Gary's wife and I would like everyone to know I was there with him at the race. I know alot men do get crap about the money, but I love him to much to give him up because I was cheap. But the truck he race's I am behind him all the way with safety. I love racing just as much as he does, so if he needs the money--go for it. Money comes and goes, but I can't replace him.

Loretta:thankyou2: *nx*
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Welcome Lorretta.
 
Loretta, my wife says thanks. Funny she was a little upset about the $$$$ I spent on the truck, but she was down right insistent about the $$$ spent on the safety gear.......Till she reread the life insurance policy. LOL
 
mswrongway said:
I am Gary's wife and I would like everyone to know I was there with him at the race. I know alot men do get crap about the money, but I love him to much to give him up because I was cheap. But the truck he race's I am behind him all the way with safety. I love racing just as much as he does, so if he needs the money--go for it. Money comes and goes, but I can't replace him.

Loretta:thankyou2: *nx*
Click to expand...

:clap::clap: Very well said.
 
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