GT40 side impact concerns

Hi guys, I am a bit concerned about the fuel tank positions on the GT40, i was watching a crash bang wollop motor racing type program the other day and they were showing some lotus 7 racing, one guy rammed the other one up the backside at about a 35mph speed difference, after a few seconds the fuel had spread around most of the underside of the car and it then went up in flames.
Looking at the replica spaceframe GT40 it doesnt seem to have much in the way of impact resistance around the fuel tanks and this is quite worrying, especially considering the increasing number of retarded drivers i'm seeing on our roads in the UK.

What steps can be done to increase side impact strength and or resistance to rupturing of the fuel tanks?

I know its mandatory to have bag tanks for racing but how effective are they?

Where are the fuel tanks located in the new Ford GT, are they sat between the engine and the driver? I believe this might be possible in a normal GT40 if using the quadcam engine as its quite a bit shorter than the pushrod motors.

Regards,
Mudgey

Valid concerns. A lot depends on what kind of chassis you are using. I believe a steel space-frame chassis provides substantially more side-impact protection to the tanks than certain monocoque designs where the exterior of the fuel tank essentially is part of the chassis. You could also use products such as explosafe in your tanks, run bladders, etc.

But the bottom line is that a GT40 with its side-mounted tanks is inherently more dangerous than a more traditional setup where you can bury a proper fuel cell deep inside the chassis, near the CG where it really belongs. You pays your price and you takes your chances.

I stewed on this for a long time, in fact it kept me from jumping in earlier. In the end, the GT40 is not a minivan. I think there are much more dangerous aspects of the car simply because of its form factor. I mean, it is only 40 inches high. If you get in a real accident with a normal car or SUV, you will be worried about other things than the fuel tanks. In fact, I believe that if I get hit hard enough to rupture a tank in my RCR, I will already be squeezed out of caring. There are very few things that will even hit the fuel tank. Most will just drive over it and through the passenger compartment.

But it is still a car, and therefore much safer than a motorcycle I actually do not really mean that as a joke.

The modern GT has the fuel tank in the very center of the car running front to back, inside the center console. I still would not want to get T-boned by a Suburban. I don't think it would go over well.

The car sits so low, that any normal vehicle is going to hit the door and probably not the tank.

Mark Worthington said:

But the bottom line is that a GT40 with its side-mounted tanks is inherently more dangerous than a more traditional setup where you can bury a proper fuel cell deep inside the chassis, near the CG where it really belongs. You pays your price and you takes your chances.

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That's the fact that kept me from really pushing my car through the Kink at Road America. Lose it there and I'd likely been "toast", both figuratively and literally. Each time I set out I remind myself that I'm driving an "old" car that can hurt me in a multitude of ways. It's also why my insurance guy says, "No passengers".

Sorry, Daryl, but are you really saying your insurance guys say no passengers, like ever? That is the first I have ever heard of that restriction for a 2 seater car! That sucks. I would change insurer next time around for sure.

As to fuel tanks, I agree with sentiment above that the tank will be overridden and you need to be more worried about cockpit penetration. Compare that risk with Cobra and Lotus 7 type cars. At least with a 40 there are a couple of beefy chassis rails out there and not just the door frame. Or if a mono chassis, a crumple zone?

Although be sure to look at how good the fuel filler cap connections to the tanks are. I have heard of various accidents, the only big fire I knew of involved an inverted 40 and the fuel caps leaked. I was also aware of a 40 that went under an articulated truck (from the side) and one of the trailer support wheels (that are off the ground when connected to a rig, you know the small steel wheels) ended up inside the cabin but no harm came to the passenger except perhaps for excessive bowel evacuation!

Just get fuel cells installed. They are expensive but worth it.

There are a few things that can make these cars as safe as they can be.

First, install a roll cage. The "A" pillar hoop over the windshield will serve to keep the minivan that t-bones you out of the drivers seat. Between it and the rear behind the seats hoop they form a very strong deflection system to prevent something like the front bumper out of the car. At least hopefully.

Second first, Install a on board fire system.

Second, run a fuel cell, a real one, and roll over valves in the fill and vent lines. At least use locking modern fuel caps under the period correct cool aluminum pop tops.

Third, install fuel electrical cutouts in the fuel pump circuits. These cut power to the fuel pumps in the event of a big impact.

Fourth, wear the full 5 point harness all the time. Well, at least 4 of them anyway.

Fifth, Drive it like its a motorcycle.

How about using only one fuel tank and leaving the other empty. That would reduce the chances of a leak from a side impact by 50 %.

I'm working on side intrusion beams for my doors which will extend from the hinge pin all the way to the latch plate. Nothing to show just yet as I'm still in the design and material acquisition phase - but rest assured, it will be there in addition to the roll cage.

Regarding the fuel tanks. You don't mention any particular manufacturer's replica. I can tell you that RCR's car has some pretty heavy duty material in the area of the tanks. I believe it's 3/16" thick around the perimeter of the fuel tanks and the internal side if the tank is a full 1/4" thick. This is all aluminum.
If you're truly concerned - you can buy bladders for the cars - or you can build a burst plate/chamber into the cells. This would reduce your fuel capacity by the size of the burst chamber, but perhaps that would not be a great concern to you.

One area to pay very close attention to is the connections between the fillers and the tanks. As has been said earlier - one good blast to the side and you could well dislodge the filler pipe and then you'd have fuel in the interior of the car.

Howard's recommendations appear quite sound to me. For the doors themselves, Australian Design Rules require an engineered "side intrusion bar" which is a horizontal steel bar in the door of a road vehicle, to help prevent accidental intrusion in a collision. In the DRB this is a hefty steel tube running from the hinges (front of the door) to the latch (rear of the door). Of course this is irrelevant to fuel tank protection, but if the occupants are physically protected, and fuel leaks are minimised, and an on-board fire suppression is installed in case fuel does leak, then chances of survival are as good as you can get.
Dalton

I wasnt particularly aiming at any manufacturers, i think all manufacturers do the best they can within reason to make the cars as safe as possible.

Big-foot that sounds really interesting, it would be good to see what you come up with, in both design and when finished. I've had a brief think about this and how would you make the latch at the rear of the door strong enough to support the tube in a collision?

My plans are to install a rollcage. I have also been thinking about whether its worth installing an extra brace between the front and rear hoops to the right of the driver, and left of the passenger, ive seen this done on some rollcages in GT40's and the tubes have been hinged.

Mike Trusty and myself witnessed (just in front of us) the crash of a GT40 in 1998 in South Florida at moroso track even I was in. I want to say it was a CAV although I can remember the make, the owner of the car has an original but raced this MK1 at events. The driver lost control after the rear left rear tire got off the tract in a right hand flat corner, instead of backing out he stayed in the throttle and the car slid sideways into a concrete flagging podium. The drivers tank (right side) had 0 fuel in it because of weight balance so he was lucky, but they had to cut him out of the car and he was in intensive care for quite some time, later he stayed at our home in the Keys to recuperate, he had more pins and wires coming out of him than an erector set. I am not sure of the speed he it but think it had to be at least 50-60 mph to a dead stop. The passenger of the car had broken ribs from the impact. If there were fuel in that tank I believe they would have both perished. Fuel blatters is what we need, Mike Trusty has been looking into having them produced but people who make them have liability issues so they are less than responsive to make them for a road car. If anyone has information on blatters please let everyone know. I am interested in a set.

Pics of my side intrusion bars fitted just inside the closed door (pics aren't the best but.....)

Malcolm said:

Although be sure to look at how good the fuel filler cap connections to the tanks are. I have heard of various accidents, the only big fire I knew of involved an inverted 40 and the fuel caps leaked.

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Malc,
Go and check out the new IVA Draft rules. We will now have to ensure that the filler necks etc are cmpletely sealed off from the river compartment. I have been in many replicas where it is not.

Brett

Big-Foot said:

I can tell you that RCR's car has some pretty heavy duty material in the area of the tanks. I believe it's 3/16" thick around the perimeter of the fuel tanks and the internal side if the tank is a full 1/4" thick. This is all aluminum.

Click to expand...

The RCR tanks are also designed so that there are no seams in the car, the top and inside surfaces of the tank are a continuous bent 1/4 plate. So the weak point is down and out. Even being the safety pup I am, I opted out of using the FIA bladders, which are available with the kit.

I will have the cage, fire suppression, extinguisher in the cabin, 6-point harnesses, fuel cutoffs, power cutoff, and rollover vents.

When I look at the way I will drive a car like this, it is early in the morning on a weekend up in the mountain twisties. The biggest threat to my safety is going to be the loose nut behind the removable wheel.

[I opted out of using the FIA bladders, which are available with the kit.]

Will Fran sell these to anyone? Wonder what size they are?

Eagle fuel cells in Wisconsin has good prices on fuel cells. They are cheaper than ATL because they are not FIA certified. They are not FIA certified because their main business is airplane fuel tanks so they are FAA certified.

Randy, Are you planning on mounting the side intrusion bars inside the door? I believe another forum member has posted pictures of doing the same. He did a nice job, but frankly I would question the effectiveness of such a mount. To me, the fiberglass door will not withstand an impact of any great speed and I would think that your intrusion bar may become a spear and do more harm than good. I like Tim's side bar because it is mounted to his cage. Just my two cents and I will see what you come up with.

Here are some pictures of 1051. The side bar is removable.





As a side note, look at the weather stripping. It sealed up real nice.