fuel system venting? (Page 1 of 2)

last i heard your fuel system needs to be sealed, and the only permitted venting is during fueling. I'm a little hazy on the whole evap system venting, but I do remember the Bang-Zoom Pow! Probe had a vent with a rollover valve, and a hose dumping to an empty rotella bottle inside the rear bumper at Southern Discomfort. needless to say, Jay noticed it and gave them a fairly stern talking-to as they were packing up after a blown motor. Best advice is going to be "Email John @ Evil Genius" as he's the de facto tech head and whatever he says, or jay says, goes.

This. Also, for some added protection (and for diagnostic purposes), toss a canister-type fuel filter on the end (Wix 33321 or Napa 3321 for example - they're stock on Gen 1 and some Gen 1.5 Dodge Dakotas) to serve as a catch-can. Note that this catch-can should ALWAYS be empty unless you've been on your roof lately. If it's not, you have verifiable evidence that your fuel system is being pressurized or heated.

That particular trick comes to me by way of some 4x4 rock-crawler dudes - who are an interesting place to go fishing for ideas because they plan for rollovers like we plan for driver changes.

Fast forward to 1:45, and ask yourself why the camera was fogging up, and contemplate the possibilities.

Link: http://vimeo.com/17974576

At 1:35 the New Yorker, or whatever it was, goes off. Also fun to watch.

Phil, here's a procedural question for you. If I'm on the track behind a car that's spilling some fluid on the car, does HQ like for us to phone that in to our spotter/pits and have them narc out the other teams, or is it better for us to just let the corner workers sort it out? In other words, does HQ appreciate and take action on reports from teams in that manner, or does it just wait on them to be outed by the corner workers? There is, of course, a chance for shenanigans from the teams...

I know that at some tracks (like Houston) the corner worker shacks can sometimes be a ways off the track and it might be hard for them to see something other than a gusher like in Tinyvette's video above.

I don't give a crap what Lemons HQ thinks.  If someone is dumping liquid on track, I want you to call it in because I don't want to spin in the fuel/water/sludge/blood/oil/vomit.

Cool. Thanks Phil.

Found this on a jeep forum,
http://www.pirate4x4.com/forum/showthread.php?p=2712471

Im pretty sure thats a rollover valve on top of the tank (they're calling it a vent valve.)  I think adding a loop or loops to the vent line will help the vapors from continuously flowing out of the tank while its parked.  The rollover valve (aka tip over valve) is only really helpful if you are upside down, then its something you really want there.  You might be able to get away without one but if it does roll it could siphon fuel until its below your vent point depending on where your vent line ends up.  If you are going to vent it this way i'd say to pony up for the rollover valve.

***EDIT Judge Phil says you definitely need the rollover valve.

They are using a fuel filter at the end as a catch can (in a rollover, just the fuel possibly in the vent line) and to keep the incoming air clean.

I was also toying with the idea of using 2 check valves plumbed in opposite flow directions in parallel in the vent line.  This would keep slight pressure or vacuum (the opening pressure or vacuum of the check valve) in the tank and would keep it from letting out fumes unnecessarily while sitting.  The check valves would have to be able to handle fuel vapors though.

Our car has the vent line going back to the tank and has a plastic (rollover?) valve stock in a similar setup to the link above.  The line that goes down goes to the front of the car where it usually goes to charcoal canister etc.  If you have a good enough air filter (not restrictive at all) you can plumb the tank vent into the intake (not the intake manifold or where it would see boost!) But if your filter is restrictive at all its probably a bad idea as it will pull a vacuum on the tank and may collapse it and/or can do strange things with running rich. The idea would be to burn the vapors.  The 2 opposing check valves might work well here too.

Just some ideas.

That's an excellent cite to the pirate board. Kudos for adding that.

In regard to the check valves, I suspect that in an ideal world, the fuel tank is operating neither under pressure nor vacuum -- pressure in this context being a positive value greater than atmospheric pressure and vacuum being a negative value less than atmospheric pressure.

A pressurized fuel tank will find the weakest joint and will spew fuel from it until the pressure in the tank is equalized with atmospheric pressure. That's really bad and will get you black flagged (at best!). If you're running a vacuum in the fuel tank, it could eventually lead to the fuel pump being unable to get fuel to your engine, which puts you back in the paddock too, although with less chance of fire. Not as bad, but still not good.

I think the check valves operate in this circumstance mainly to stop the flow of liquid fuel and not vapors. If you have pressurized fuel vapor (which, as Rob notes, is normal due to the return of heated fuel to the tank) then it's valuable to let those vent naturally and while they're still at a low pressure level (above atmospheric) so that the pressure doesn't break something.

IMHO. Cheers!

Yes, i agree you dont want very much pressure or vacuum on it at all.  The vacuum or pressure im talking is minimal, like .1 of a PSI.  Most check valves you can easily blow on or suck on (in the right direction) and they will open.  Fuel slosh should have more energy than the vac or pressure im talking.

  OBD-II cars have to be able to handle at least 1psi of pressure.  Some (all?) use a map sensor to watch what the system is doing to figure out if there is a leak.  1psi is probably a lot for our crap cans though.

On our car the tank is in the trunk right below the rear deck.  Theres 2" from the tank to the deck.  Not really ideal for the link to the 4x4 style vent.

So the ideal part I think is a discriminator valve.  The only one i can find is by ATL, part # TF475.  Its supposed to have a float that blocks fuel from going out the vent.  Im sure there are others.  I'll post if i find some.

The gas wave smashing the cap thing sucks.  Not much you can do without adding baffles or foam to the tank or going fuel cell.

  Lemons sells ATL now on their store, im sure everyone got the email about that today.

Judge Phil, does that go for OE tanks too?  I didnt see anything in the Lemons rules about the roll over valve.  I know our car has a "gravity valve" in the vent stuff but not sure if all OE setups have these.

A cheap & easy to add 3/8" OD rollover valve
http://www.pegasusautoracing.com/produc … ?RecID=899
You might have to pull it out of the vent hose and show tech as its very hidden but easy to add.  The piece of hose its in needs to be secured well so it actually works and doesnt flop over (and not work) in a roll.

Most (maybe all?) of the discriminator valves are roll over valves plus a float valve in one.  Here's a few i found that say they are also a rollover valve,

http://www.polyperformance.com/shop/Dis … -2821.html  (FS-ITDV08 in the drop down) This one looks like a normal bulkhead fitting and probably wouldnt be easy to add to most tanks unless you put an adapter on the threaded part and run a hose to the tank.

http://www.pegasusautoracing.com/produc … RecID=7265   This one is not cheap, its -12.

http://www.jegs.com/i/ATL/046/TF475/10002/-1  Only pic i could find on this is on ATL's site in their catalog.  http://atlinc.com/2010_Race_Catalog/page22.html  It looks like a bulkhead style.

The bulkhead style could work well if you could find the right adapter & can seal the threads well.  A simple bracket then just to keep it upright.

This is the slight pressure/vacuum valve thing i was talking about to keep vapors down, i didnt know anyone actually had these.   http://www.pegasusautoracing.com/produc … RecID=8453 but it opens at .875psi which might not be crapcan seasoned tank friendly.

The rollover valve isn't required in the rules, but when we find a tank vent system that looks like it's going to dump fuel if the car flips we usually make the team obtain and install one. This happens more often on fuel cell setups.

There's a lot of subjective interpretation going on with fuel-system safety, and Jay's nightmares about cars becoming big fireballs tend to make him err on the side of safety overkill. Your best bet is to imagine everything that could possibly go wrong with your fuel system and fix it before you get to the track.