fuel cell vent question
Thread Starter
Teching In
Joined: Nov 2005
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fuel cell vent question What size vent are you guys using in your fuel cells? This will be a 427 LSX S91 turbo @ 20-25psi.
The fuel cell currently has a -08 for the vent alon with a -08 return, but I do not want to starve this engine for fuel so I want the vent big enough....
Chad
The fuel cell currently has a -08 for the vent alon with a -08 return, but I do not want to starve this engine for fuel so I want the vent big enough....
Chad
I used one of the standard ones from Summit for my (admitedly untested) build. 8AN should be more than enough though, unless you're under some very unusual circumstances.
If you're really concerned about it, you could just install another one. What's the capacity of your fuel cell? Better yet, what are the dimensions?
If you're really concerned about it, you could just install another one. What's the capacity of your fuel cell? Better yet, what are the dimensions?
The Weldon 2345-A fuel pump is advertised to flow 250 GPH at 75 PSI. That's good for ~ 2000 HP, according to their numbers.
Let's imagine (for fun) that you're using ALL of your fuel, and your regulator isn't returning anything. That pump is absolutely maxed out. That 250 GPH will evacuate ~ 4.15 gallons (around half of your tank) per minute, or about 0.65 cubic feet per minute (CFM), or around 19 cubic inches per second. Your tank is, after all, only ~1.34 cubic feet (probably to the outside, not internal volume).
So your vent only has to flow a little better than 1/2 of a cubic foot of air per minute (rounding down a little) even in this extreme (and unrealistic) scenario. 8AN is a large fitting, 1/2 inch OD. 1/2 OD won't have a bit of trouble flowing 1/2 cubic feet per minute.
If you're not convinced then do this: Pick up the 8an fitting and draw through it. (Don't choke on it.
) The average human lung holds around 0.2 feet^3, or 345 in^3 of air. You need 19 cubic inches per second at this point. How long did it take you to draw the air through that opening? Did you feel much resistance, or any at all? If you can get 300+ cubic inches through it in a few seconds with little effort, you aren't going to have any trouble getting 1123 in^3 (0.65 feet^3) through it in 60 seconds.
If THAT doesn't convince you, install another one.
Oh, and listen to Old Geezer, best advice in this thread...
Let's imagine (for fun) that you're using ALL of your fuel, and your regulator isn't returning anything. That pump is absolutely maxed out. That 250 GPH will evacuate ~ 4.15 gallons (around half of your tank) per minute, or about 0.65 cubic feet per minute (CFM), or around 19 cubic inches per second. Your tank is, after all, only ~1.34 cubic feet (probably to the outside, not internal volume).
So your vent only has to flow a little better than 1/2 of a cubic foot of air per minute (rounding down a little) even in this extreme (and unrealistic) scenario. 8AN is a large fitting, 1/2 inch OD. 1/2 OD won't have a bit of trouble flowing 1/2 cubic feet per minute.
If you're not convinced then do this: Pick up the 8an fitting and draw through it. (Don't choke on it.
) The average human lung holds around 0.2 feet^3, or 345 in^3 of air. You need 19 cubic inches per second at this point. How long did it take you to draw the air through that opening? Did you feel much resistance, or any at all? If you can get 300+ cubic inches through it in a few seconds with little effort, you aren't going to have any trouble getting 1123 in^3 (0.65 feet^3) through it in 60 seconds.If THAT doesn't convince you, install another one.
Oh, and listen to Old Geezer, best advice in this thread...
Thread Starter
Teching In
Joined: Nov 2005
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Nah that will work...Like I said I just wanted to make sure.
1 return and 1 vent with a roll over valve....
This is not my first car that I am putting together but it is the first one with this kind of power potential...covering all my bases....
I figured it would be alright but I sure would have felt silly if I would not have asked and there was a problem.
Thanks
1 return and 1 vent with a roll over valve....
This is not my first car that I am putting together but it is the first one with this kind of power potential...covering all my bases....
I figured it would be alright but I sure would have felt silly if I would not have asked and there was a problem.
Thanks
