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So the NASA tech shop that I'm working with pulled the OEM tank and we took a look.
It was very interesting and not quite what I expected. For some reason, I thought I read that the tank was plastic. It's not. That was one of the reasons I didn't initially suggest modifying the tank... I didn't think welding would work because of the material of the tank. But the tank is metal.
I know this is old news to some of the track guys, but there hasn't been a great "drop in" solution or pictures of a build yet.
Looking inside the tank, underneath where the fuel pump sits there is a small, shallow "basin." It looks like an emesis basin you'd find in a hospital. I can totally see how a non-smooth driver (e.g. me) can "throw" the gas out of that basin and actually make things worse than if there was no semi-swirl pot at all.
There are no check valves in that mini swirl-pot.
I wonder if that basin also serves a function in serving as a reserve tank when you're nearly out of gas in normal driving. So if you're on empty... don't throw the car around!
In talking with my shop, we're going to cut an access panel in the top of the tank and remove the little basin, replacing it with a larger swirl-pot with one-way check valves.
That's what krazik meant when he said "[Honda] didn't complete the baffle."
Note that this is not autocross "stock" legal, but allowed in some other classes. Not sure how it falls into NASA points and SCCA road racing classing.
If it goes well and if there was interest, they'd be able to offer this tank modification to others as well. Their labor rate is very cheap ($60/hr) and they do great work.
We talked about maybe offering a "core exchange" service. Note that you need to take the subframe off to remove the gas tank. So if you're having work that requires that kind of labor, it might be a good time to consider it.
Here are some crappy iPhone pictures. You can see the basin peeking through the fuel pump hole.
This sounds much better than buying a fuel cell. I like working with what I've got, and I prefer the grassroots type of approach to setting up a track car. I'll be watching this one.
No it would not be legal for STR,but the only way you would be protested would to tell someone about the mod to your fuel tank.
Hypothetically speaking, I'm pretty sure a person who would do this would get protested (at least on a national level) as they would be the only S2000 able to run no fuel. If there was a way to do this legally, I would be on board in hopes of building a sub 2600lb STR legal S2000.
Thanks for posting this info up CKit, nice to fimnally see what the problem is. Post up more pics as it progresses!
Originally Posted by sirbunz,Dec 19 2009, 11:46 PM
Hypothetically speaking, I'm pretty sure a person who would do this would get protested (at least on a national level) as they would be the only S2000 able to run no fuel. If there was a way to do this legally, I would be on board in hopes of building a sub 2600lb STR legal S2000.
Thanks for posting this info up CKit, nice to fimnally see what the problem is. Post up more pics as it progresses!
-Marc
sub 2600lbs shouldn't be an issue. You can run down to a 1/4 - 1/3 tank of gas in STR trim with the stock tank and not starve at all.
How about those razor sharp edges? I found it interesting that the bowl isn't the lowest point either. I wish the tank just had a deep sump in it with straight walls.
12-19-2009, 01:13 PM
OEM Fuel Tank setup to minimize fuel starve
I'll be watching this one.
