While adding an extra fuel tank to the 'Shasta Bus' that friend Greg Urrittia and I will race in the upcoming Beetleball 24 rally, we were discussing how to get this done with the least amount of hassel. Afterall, we had to get it finished quick and had a huge laundry list to accomplish and not much time to do it all. There was 'the rules' and there was "what's safe". I made up my mind, "I either install this thing to safely survive an accident, or I don't install it at all".
After borrowing a bunch of parts, fuel lines, and gathering up all my braided hose and Earl's fittings, I took a step back and looked at the possible safety issues. The rules allow another fuel tank (they say fuel cell) we looked at available buggy tanks we had, fuel cells, even an OEM tank we might mount inside a truck toolbox, for secondary containment.
If you are building a competition car, or modifying a fast car, I challenge you to do the same thing. Gasoline is dangerous stuff that needs to be respected. Any leak at the wrong time could be an absolute disastor.
I have tech'ed a lot of racecars, and you'd be amazed at some of the stuff I've seen. Everyone has their own idea on what is good enough, but take a look at the pro built cars... those purdy lines and tanks aren't there to impress car show judges, they are for safety just in case the car gets on it's lid. When the stuff hits the fan, the last thing you want is a fuel system that spews liquid fuel everywhere looking for a spark. Look at any wrecked asphalt racecar, they all have one thing in common: Steel that scraped on the pavement and you just know, created a shower of sparks!
A few truths:
Gasoline liquid doesn't burn, the vapor that boils off does. Fuel tanks generally don't 'explode', they leak, which forms a pool that evaporates. The vapor will burn pretty hot, and keep burning until the liquid is consumed. Having said that, a fuel leak is your worst enemy. The vapor hangs heavy in the air and is just begging for an ignition source to start it burning.
Fuel lines: Every aircooled VW owner knows how lousey the cloth braided line is, after 5 years, it's easily cracks and leaks. Stock OEM carbs have pressed in nipples that often fall out and spray pressurized gas all over the engine. Almost every VW old timer has experienced this. If you modify your fuel system beyond stock (ie, add dual carbs and electric fuel pump) I would strogly consider re-plumbing the entire system, from the fuel tank tot he floatbowls with stainless steel braided lines and AN fittings.
Routing: No exposed fuel lines inside the car! Inside the tunnel, sure. No rubber lines in the vacinity of the rotating flywheel... that is to say, if the flywheel comes apart, it flys outward, there should not be a rubber line to be cut in the line of fire! SS braided or steel tube only, several inches either side of the bellhousing. If you must use some rubber fuel line, use no more than a total of 12" and only in places were you need a flexible joint. In fact, these are NHRA rules.
You might not ever race at an NHRA member track, but lets have a show of hands, who wants to get burned?
Fuel tanks: If you can, use a foam-filled plastic or aluminum fuel cell. IF either of these happen to grind across the pavement, they won't create sparks. Mount the fuel tank withing some bodywork, with the pretimiter of some chassis or roll cage tube, or something to protect it from being drug across the pavement should the car slide 'fuel tank down'. Make a 'roll-over' vent hose. Either use a ball-check valve or a pig-tail loop a couple inches above the fuel tanks. Usually a simple vent hose becomes a direct leak if the car is on it's side.
After borrowing a bunch of parts, fuel lines, and gathering up all my braided hose and Earl's fittings, I took a step back and looked at the possible safety issues. The rules allow another fuel tank (they say fuel cell) we looked at available buggy tanks we had, fuel cells, even an OEM tank we might mount inside a truck toolbox, for secondary containment.
If you are building a competition car, or modifying a fast car, I challenge you to do the same thing. Gasoline is dangerous stuff that needs to be respected. Any leak at the wrong time could be an absolute disastor.
I have tech'ed a lot of racecars, and you'd be amazed at some of the stuff I've seen. Everyone has their own idea on what is good enough, but take a look at the pro built cars... those purdy lines and tanks aren't there to impress car show judges, they are for safety just in case the car gets on it's lid. When the stuff hits the fan, the last thing you want is a fuel system that spews liquid fuel everywhere looking for a spark. Look at any wrecked asphalt racecar, they all have one thing in common: Steel that scraped on the pavement and you just know, created a shower of sparks!
A few truths:
Gasoline liquid doesn't burn, the vapor that boils off does. Fuel tanks generally don't 'explode', they leak, which forms a pool that evaporates. The vapor will burn pretty hot, and keep burning until the liquid is consumed. Having said that, a fuel leak is your worst enemy. The vapor hangs heavy in the air and is just begging for an ignition source to start it burning.
Fuel lines: Every aircooled VW owner knows how lousey the cloth braided line is, after 5 years, it's easily cracks and leaks. Stock OEM carbs have pressed in nipples that often fall out and spray pressurized gas all over the engine. Almost every VW old timer has experienced this. If you modify your fuel system beyond stock (ie, add dual carbs and electric fuel pump) I would strogly consider re-plumbing the entire system, from the fuel tank tot he floatbowls with stainless steel braided lines and AN fittings.
Routing: No exposed fuel lines inside the car! Inside the tunnel, sure. No rubber lines in the vacinity of the rotating flywheel... that is to say, if the flywheel comes apart, it flys outward, there should not be a rubber line to be cut in the line of fire! SS braided or steel tube only, several inches either side of the bellhousing. If you must use some rubber fuel line, use no more than a total of 12" and only in places were you need a flexible joint. In fact, these are NHRA rules.
You might not ever race at an NHRA member track, but lets have a show of hands, who wants to get burned?
Fuel tanks: If you can, use a foam-filled plastic or aluminum fuel cell. IF either of these happen to grind across the pavement, they won't create sparks. Mount the fuel tank withing some bodywork, with the pretimiter of some chassis or roll cage tube, or something to protect it from being drug across the pavement should the car slide 'fuel tank down'. Make a 'roll-over' vent hose. Either use a ball-check valve or a pig-tail loop a couple inches above the fuel tanks. Usually a simple vent hose becomes a direct leak if the car is on it's side.
