Hi Everyone - I'm new to the forum and am hoping folks can help me understand more about adding a fuel cell in an NC Miata or solve my fueling issue which is my preferred solution. So I'm reaching out to folks who have experience in this.

I do endurance racing with Lucky Dog and efficient fueling at the pits can make the difference between being on the podium or not. The stock NC fuel pipe to the stock fuel tank chokes down to a size that restricts the flow of fuel and prevents using fuel cans that have large openings. A fast flow can (1" id output) puts fuel in faster than the stock tank/filler pipe can take it and so the fuel "burps" back out. I have gutted out the restriction at the top of the filler tube so this is not the problem. I have also increased the size of the air vent which did not improve fueling efficiency. I am able to fill without problem when I use gas cans with a 5/16" id outlet, however, this is excruciatingly slow. The only solution I have come up with is to put in a fuel cell so I can "dump" fuel in quickly.

Questions:
1. How difficult is it to install a fuel cell in an NC?
2. What capacity of tank can I install in an NC without making major modifications.
3. Do fuel cells "time out" like seat belts, etc.?
4. Is there a preferred fuel tank brand?
5. Is there another solution to my fueling problem?

Thanks for your help!

 

1. anything's possible with a cut off wheel and skilled fabricator.
2. Typically you look at capacity needed (use burn calcs to determine total capacity for a 2 hour stint), then look at what size you'd need to make that fit, then what's actually readily available. Custom cells are an option, but more $$$
3. Yes, they have cert dates and time out.
4. Pyrotect, Radium, and Fuel Safe to name a few. But LD has a discount with Pyrotect, that's probably where you should start looking. Unfortunately roll cages and fire walls often have to be modified to make them work.
5. Probably. My main experience is with NAs, but typically once you gut the emissions restrictions out of the filler neck, you can use a quick dump can like a Hunsaker with well over a 5/16 line as long as the tank vents air efficiently. 5/16 is ridiculously small. They come with a 1", and we neck down to 1/2 or 3/4 for stock necks.

Take each component off separately. Take the filler neck and tube off and dump 2 gallons from a hunsaker into a 5 gallon bucket. It should go in within 5-7 seconds. My guess is it will, and you're dealing with a venting problem. They're often quite small from the factory. Take the tank out and see if you can modify it.

Quick search shows one small vent, which is probably returning to the neck. If this gets obstructed with a filler nozzle, you'll have a problem. The 2nd corrugated line is probably for the charcoal canister, but can also help by acting as a vent, make sure while someone is dumping fuel in, the other end of that, wherever it is, is venting air. If it comes down to it, drop the tank, drill a hole in the top, and add a sealed bulkhead AN connector, and vent it to a discriminator/roll over valve.

You can also add your location to your profile, so others in your area can perhaps give you advice for fabricators/race shops.