Fuel tank

[Alister McBride]

Just wondering what other teams are doing with their tanks to combat fuel surge?

Is there anyone using 2 pick ups? If so, how do you ensure no air is drawn from either pick-up?

[Alister McBride]

Just wondering what other teams are doing with their tanks to combat fuel surge?

Is there anyone using 2 pick ups? If so, how do you ensure no air is drawn from either pick-up?

[Kirk Feldkamp]

By fuel surge you mean the fuel sloshing around?

-Kirk

[Sam]

use foam dude, and design your tank well so that there is a pickup channel

[Kirk Feldkamp]

Yeah, the open cell foam is crucial. It's a million times earlier than baffling, and it takes up like <3% of the total volume you put it into. Plus, it's easy to cut (bandsaw) and can be removed as necessary. The only thing you need to make sure about is that you have a hole in the tank that is big enough to get your hand in to stuff the foam in there!

As far as keeping the fuel around the pickup, just make a little fuel box. The way we do it is we have 2 little flapper gates that only allow the flow in, and not out. After a few turns, the fuel box is full and the pickup wont suck any air. The fuel box with the foam is an unbeatable combination. I don't know where we got the little flappers, so you're on your own there. I think most manufacturers use a ping pong ball box to achieve the same thing.

-Kirk
UC Berkeley

[Alister McBride]

Yes by fuel surge I mean fuel sloshing around

[Jackson]

Where can I get this magical Open Cell Foam you guys are referring to?

Sounds like the way to go to me.

Brian
Washington State U FSAE

[James Waltman]

You can find it here:
http://www.fuelsafe.com/replacementparts.html

It might not work for teams running E85. Check out the FAQ section:
http://www.fuelsafe.com/FAQ.htm

[Simon]

We've had a fuel surge problem with the 2003 car, which we wanna fix this year, so we're looking at the alternatives.

Does anyone have experiences with running a scavange pump?

I've heard that in tank pumps need to be submerged in fuel for cooling, which means that they wouldn't be happy when your down to the last litre or so. Has anyone fried an in-tank pump because of this? Has anyone found that in-tank pumps are less reliable?

Any other suggestions for fixing surge would also be appreciated.

Simon de Lisle
srde3@student.monash.edu.au
Monash Uni, Australia

[Colin]

Just a warning about the fuel foam, make sure you use the correct foam, i pulled apart our 2001 fuel tank one day to get the pump out and found the pickup filter and pump full of little bits of the fuel foam, needless to say i didn't use the pump. the last two years we've used one way swing gates with good success and as our tank is below the drivers knees not behind the seat so our tank is wider than it is high so surge is a big issue for us, this year we're running a combo of fuel foam and swing gates.

To Simon: as for scavenge pumps and surge tanks I'm sure everyone would run that sort of set up if they could but can you really justify the extra weight?

I've also heard that in tank pumps need to be submerged, we've used in tank pumps for the last three years with out a failure and if you look at OEM bike pumps they are only completely submerged when the tank is full. I've been running an in tank pump externally on my road car for 3 years without a failure, so i wouldn't stress about it too much, remember if you are running a return line you get a very hi flow rate through the pump which aids in cooling anyway.

[A.Bejcek]

To answer your initial question, my team (Kettering University) is using dual fuel pump pickups, and I know of at least one other team which is using dual pickups. The fuel is drawn from pickup "pods" which are essentially valves that seal up as soon as they are no longer submerged in fuel. The pods that we use are from snowmobile gas tanks and they are made by Walbro Engine Management. I will try to find out what snowmobiles they can be found on and post it later.

In tank pumps usually do not need to be submerged for cooling. Fuel pumps are constructed such that Fuel is drawn through the pump motor. This fuel flow through the motor is what accounts for the majority of the pump's cooling. So... I wouldn't worry about running the pump non-submerged, but do worry if you run out of gas and run the pump while it is dry internally.

[Bob T]

Our team uses an electric bottom-feed in-tank fuel pump inside a plastic resevoir that is open at the top. This whole assembly is inside the tank. The resevoir fills whenever the tank is filled and is used as a backup source whenever the primary feed is starved. We also use the previously mentioned open cell foam. The hardest part is making the mounts and positioning the pump as close to the bottom of the tank as possible without pressing it against the bottom of the tank and cutting off the feed. This setup has worked very well for us.

[Ani_V]

Ours is a gravity fuel feed engine. I have contacted many mechanics and bikers around and they told me that we would need to mount the fuel tank above the engine. Now Mr. Claude is very critical of the safety factors and he might do us in for this. Can you suggest any measure to mount the fuel tank at the base. <<< Mounting it below and using the fuel pump would flood da carb, engine would run rich.>>

[Tech Guy]

Ani V,
Believe it or not, before fuel injection, engines with carburetors had fuel pumps! At least those in cars did. So your solution is a simple one. Mount the fuel tank down low as Claude said, use a fuel pump (probably an electric one as you are probably using a motor cycle engine), and crank the fuel pressure regulator down to a very low level so as not to overpower the needle valve in the carburetor bowl. Try and use what is between your ears!

[kapps]

Do some searching. Many carburetors need low fuel pressure (~3-4 psi). There are electric fuel pumps designed for these conditions.

[Adambomb]

I had a very interesting setup on my '85 Nissan pickup. It had a carb and electric fuel pump. Instead of having a pressure regulator, it simply had a 5/16" feed line and 1/4" return line. At the entrance to the carburetor there was a tee from the 5/16" feed line to the 1/4" return line. Simple as that. In other words, fuel pressure equaled line loss in the return line. This worked fine, as there really only had to be enough pressure to fill the fuel bowls.

But pretty much every car made after 1930 had a fuel pump. I remember hearing about really old cars with gravity feed fuel systems. Back then a lot of them were mounted behind the engine, so that hill-climbing was limited to the angle where the fuel tank could no longer feed the carb. There was a story of a hill climb some time before the '20s or so where someone won because they decided to drive up it backwards.

The only time you "need" to mount the fuel tank above the carb is if you have a gravity feed system. That's generally the case with bikes, which is easy because that's where they "usually" go (one notable exception being Buells with fuel-in-frame). Outside of that, all you need is to be able to get enough pressure to get fuel into the bowls. Naturally, any more than 5-10 psi will blow fuel past the needle and seat, making for a very unhappy carb. 3-4 psi is the accepted "average."

[ZAMR]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Bob T:
Our team uses an electric bottom-feed in-tank fuel pump inside a plastic resevoir that is open at the top. This whole assembly is inside the tank. The resevoir fills whenever the tank is filled and is used as a backup source whenever the primary feed is starved. We also use the previously mentioned open cell foam. The hardest part is making the mounts and positioning the pump as close to the bottom of the tank as possible without pressing it against the bottom of the tank and cutting off the feed. This setup has worked very well for us. </div></BLOCKQUOTE>

We have a similar setup without the foam. We have a removeable (from the bottom of the tank) assembly with a narrow, upright, open ended cylinder that houses the high pressure in-tank pump. Another in-tank low pressure pump continuously fills the cylinder. It is quite simple and makes removing the tank a breeze. You just pull off the single gas line and unbolt it. No pumps to worry about outside. It has a window so you can see how it all works (or if anything is broken, a good diagnostic tool) too.

[AxelRipper]

for the carb problem you might consider doing something like we did when we ran a carb at comp last year. we made a small tank that sat above the carb and allowed the fuel to gravity feed down from that into the carb. put that in, then run a line in from your primary tank and fuel pump, and then a return line at the top of the secondary tank back to the main tank. this keeps the pressure low enough for the carb, and allows a steady flow of fuel to it as well

[OptimumG]

One of the many opportunities of the FS / FSAE competitions offers is to train potentail future employees of the automotive industry. With energy saving and emission reduction goals in mind no one of today's car / engine manufacturers would think of carburetors as a solution.

Come on guys you live in the 21st century! You should think about electrical cars. If you are still a fan of internal combustion engines, why not at least consider your own ECU direct injection? But please forget about carburetors!

[AxelRipper]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by OptimumG:
One of the many opportunities of the FS / FSAE competitions offers is to train potentail future employees of the automotive industry. With energy saving and emission reduction goals in mind no one of today's car / engine manufacturers would think of carburetors as a solution.

Come on guys you live in the 21st century! You should think about electrical cars. If you are still a fan of internal combustion engines, why not at least consider your own ECU direct injection? But please forget about carburetors! </div></BLOCKQUOTE>

As correct as this is, I must disagree with this. We were forced to run a carburetor at competition last year because we had not successfully gotten our engine running reliably on the EFI system. That is a hard thing for a small team to do, as other things begin taking priority over the EFI, such as completing the car. That is why we switched to the 2 year car rotation, because it takes time and manpower to properly calibrate the ECU. Yes, it also takes time to calibrate the carb, but once it is close, it will run whereas EFI systems can be finicky, especially on formula cars.

Another reason to do a carb is the cost. Even if you go to Megasquirt, by far the cheapest way to actually tune your engine, you're still out a couple hundred just for the computer, not to mention all of the sensors in order to make it work. I am not sure how a stock ECU from a fuel injected bike would work with the restrictor, but I'm going to guess that it isn't going to work very good.

I think for a lot of the new teams coming into this sport, the carb is a good way to go until they get their program developed, especially if they happen to be running an older engine that was not fitted with EFI originally... this can cause a problem with sensors that can take a few years to work out.

Just wanted to put that out there

[Pradeep]

The old Contessa car had an external low pressure fuel pump which you could use to feed fuel from primary tank to a small tank above the carb.
Check with a few local mechanics, it should not be difficult to find.