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E30 fuel cell setup


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26 minutes ago, Originalsterm said:

Is anyone willing to share info on their fuel cell setup in an E30?  Which shape/brand/size/configuration should I start with or avoid?

But the OEM system works...

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29 minutes ago, Originalsterm said:

Is anyone willing to share info on their fuel cell setup in an E30?  Which shape/brand/size/configuration should I start with or avoid?

 

Recommend not putting a cell in E30.  The stock tank is very well protected, low, and centrally located.  Driveshaft prevents a cell from going in the same location, so your cell would be in the trunk.  This does a few things:

 

1. Moves fuel system from inside the cage to outside where it's not protected

2. Moves the mass closer to the end of the car, which is a negative for handling

3. Makes your F/R weight distribution change more dramatically as you burn fuel, so car will get pushy as fuel load decreases

4. Takes a convenient place for packaging an enormous diffuser and fills it with something that's not a diffuser

 

Instead, I recommend the stock 16 gallon tank with dual lift pumps and a surge tank system.  Much better than a cell in the E30 as an overall package.

 

Edited by Hi_Im_Will
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40 minutes ago, Hi_Im_Will said:

 

Recommend not putting a cell in E30.  The stock tank is very well protected, low, and centrally located.  Driveshaft prevents a cell from going in the same location, so your cell would be in the trunk.  This does a few things:

 

1. Moves fuel system from inside the cage to outside where it's not protected

2. Moves the mass closer to the end of the car, which is a negative for handling

3. Makes your F/R weight distribution change more dramatically as you burn fuel, so car will get pushy as fuel load decreases

4. Takes a convenient place for packaging an enormous diffuser and fills it with something that's not a diffuser

 

Instead, I recommend the stock 16 gallon tank with dual lift pumps and a surge tank system.  Much better than a cell in the E30 as an overall package.

 

All valid points that we've considered.

 

However, I have a 318 which does not allow me 16.5 stock gallons of fuel, so I must run the smaller 14.5 gallon tank (although in the favorable stock location). Running 2+ gallons with a fuel cell plus a surge tank will allow us to extend the track time to fuel every other driver stop.  That is the only motivation towards a fuel cell from the stock configuration (plus surge tank).

 

If this is not enough of a motivation to move to a fuel cell then my money is best spent elsewhere, which I am perfectly fine with.

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3 hours ago, Originalsterm said:

All valid points that we've considered.

 

However, I have a 318 which does not allow me 16.5 stock gallons of fuel, so I must run the smaller 14.5 gallon tank (although in the favorable stock location). Running 2+ gallons with a fuel cell plus a surge tank will allow us to extend the track time to fuel every other driver stop.  That is the only motivation towards a fuel cell from the stock configuration (plus surge tank).

 

If this is not enough of a motivation to move to a fuel cell then my money is best spent elsewhere, which I am perfectly fine with.

 

Ohh, I see where you're going.  I might have a solution for you, at least for the 7 hr races.  Been brewing a reserve system that drains the tank completely while under full power, gives you a warning, then the driver flips a switch and gets a single lap to get back to the pits under full power before there's zero fuel left in the car.  Designed for just that kind of strategy where you need to stretch to the last drop, like waiting out the FCY for your single fuel stop.  About to kick off machining so I can use it at VIR, and would be happy to build you one.

 

Along with that, maybe you could argue for +2 gallons without a cell?  Might start a forum fire if you push that here, but worth asking nicely in a phone call.

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11 minutes ago, Hi_Im_Will said:

 

Ohh, I see where you're going.  I might have a solution for you, at least for the 7 hr races.  Been brewing a reserve system that drains the tank completely while under full power, gives you a warning, then the driver flips a switch and gets a single lap to get back to the pits under full power before there's zero fuel left in the car.  Designed for just that kind of strategy where you need to stretch to the last drop, like waiting out the FCY for your single fuel stop.  About to kick off machining so I can use it at VIR, and would be happy to build you one.

 

Along with that, maybe you could argue for +2 gallons without a cell?  Might start a forum fire if you push that here, but worth asking nicely in a phone call.

Last year I petitioned for 2.5 gallon surge tanks IF the car didn’t also have a fuel cell. It was rejected. 

Edited by enginerd
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1 hour ago, Hi_Im_Will said:

 

Ohh, I see where you're going.  I might have a solution for you, at least for the 7 hr races.  Been brewing a reserve system that drains the tank completely while under full power, gives you a warning, then the driver flips a switch and gets a single lap to get back to the pits under full power before there's zero fuel left in the car.  Designed for just that kind of strategy where you need to stretch to the last drop, like waiting out the FCY for your single fuel stop.  About to kick off machining so I can use it at VIR, and would be happy to build you one.

 

Along with that, maybe you could argue for +2 gallons without a cell?  Might start a forum fire if you push that here, but worth asking nicely in a phone call.

 

I'm game to hear more!

 

National tech told me running the 325 tank wasn't legal (+2 gallons over 318) and running fuel displacement to keep capacity stock wasn't legal. I'd like to petition for "any tank within the platform/generation" but it won't help me this season.

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@Originalsterm See below.  It's a 2qt surge tank with a reserve tank inside. Hooks up just like a normal surge tank - feed with lifts, draw with pressure, and provide a return back to the main tank.  The system is designed such that the reserve is always full.  As you drive, the surge portion works like a normal surge tank, making sure the pressure pump inlet always has fuel, even if one of the lift pumps runs dry.  When the main tank goes empty, the surge will eventually run down and this will show up either on your fuel pressure sensor or the level sensor inside the surge (or as a stutter, if you don't like warning lights).  That's your warning - assuming you have the lifts positioned well, the car is about to be dead on the track (see our Pittsburgh Sunday race last year, CC Live caught that happening to us).  Flip a switch to turn on the reserve pump, and it will feed your pressure pump the 1qt of fuel in reserve, which should be just enough to get you back around to pit lane under full power.   No guessing on range, this guarantees you pit on the last possible lap.  

 

Put a couple renders below to give you an idea what it looks like.  The tank is drilled for -6 ORB, so you can set it up for AN, barb, or whatever else you like.  Includes everything shown in the exploded view, but I can make the bracket too if there's enough interest to make it worthwhile.  

 

3351675_Reservesurgediagram.thumb.JPG.46c20cb9db1cbc20db1b11142f408fb8.JPG1154447560_reservesurgeexplodedrender.thumb.JPG.cb462a0659711238e761e907bfaaace2.JPG682435529_reservesurgerender3.JPG.09f6394316c153357a76ae60ffe90a73.JPG

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Another dumb question, is this any different than a normal surge tank?  Why the switch to the reserve tank (maybe I dont understand where this reserve tank is stored).  We have a surge tank with a level sensor in it, once the tank starts to drain a light is triggered on the dash that says PIT NOW, you have a basically a full lap worth of fuel.  Same idea, just no extra switch.

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1 hour ago, thewheelerZ said:

Another dumb question, is this any different than a normal surge tank?  Why the switch to the reserve tank (maybe I dont understand where this reserve tank is stored).  We have a surge tank with a level sensor in it, once the tank starts to drain a light is triggered on the dash that says PIT NOW, you have a basically a full lap worth of fuel.  Same idea, just no extra switch.

 

Not a dumb question at all.  Mechanically different because there's two chambers inside - one is your normal surge tank, the other is the reserve.  The reserve is always full, and only gets used on command. 

 

The big advantages to this method over just pitting when the surge starts to get low are:

 

-This system is not reliant on a level sensor to tell you when to pit.  Fuel level sensors are inherently inaccurate when there's a ton of slosh.  Putting the sensor in the surge helps, and the sensor can be mechanically damped to help some more, but once that surge starts running low the sensing gets less accurate. In the reserve system, the sensor is a secondary piece of information.  It's confirmation that you're low, not that only indication.  Even if a sticky sensor fails to warn you, and the tank runs dry, there's still 1qt available to get you back to the pit lane under full power.  In fact, the sensing circuit isn't even required- you could just wait for the engine to stutter and use that as the level warning.  Then flip switch to get full power back, and drive to pit lane at race pace.

 

- The reserve system is NOT automatic.  This is a feature.  With a traditional surge system, a red-misted driver can miss the warning and run out on track (again, see PIRC). With the reserve, they have to flip a switch to keep racing, which forces them to acknowledge that it is time to pit.

 

- When the warning comes, your remaining fuel is consistent. With a surge, the remaining level at the warning is an ugly function of related pump flow rates, capacities, main tank geometry, and g loading.  All that results in huge variation in remaining fuel car to car, and large variation stint to stint.  With the reserve system, you have 1 qt at the warning, every time, on every car.  No learning and no guessing.

 

Keep asking!

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Another dumb question; Since the surge tank is only allowed to hold half a gallon does this mean that if the main tank is completely empty, and the surge tank is at it's 2 quart capacity, that the surge tank would have 1 quart of fuel and the reserve tank the other quart of fuel?

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15 minutes ago, thewheelerZ said:

Is this like a tank inside a tank, does the reserve overflow into the surge so the reserve is always full?  Seems like a cool idea.  Quick pre-race test just to make sure the reserve pump is still working and basically good to go.

 

Yup, that the idea.

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3 minutes ago, Richard said:

Another dumb question; Since the surge tank is only allowed to hold half a gallon does this mean that if the main tank is completely empty, and the surge tank is at it's 2 quart capacity, that the surge tank would have 1 quart of fuel and the reserve tank the other quart of fuel?

 

Correct, the total volume is 2qts, split between the surge chamber and the reserve chamber.

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23 hours ago, Originalsterm said:

All valid points that we've considered.

 

However, I have a 318 which does not allow me 16.5 stock gallons of fuel, so I must run the smaller 14.5 gallon tank (although in the favorable stock location). Running 2+ gallons with a fuel cell plus a surge tank will allow us to extend the track time to fuel every other driver stop.  That is the only motivation towards a fuel cell from the stock configuration (plus surge tank).

 

If this is not enough of a motivation to move to a fuel cell then my money is best spent elsewhere, which I am perfectly fine with.

This is not correct, internet specifications do not work. By the end of production BMW was using whatever tank was laying around, M42 cars have been seen with the 16 gallon tank. I cannot speak for the M10 318, although unless you are running a turbo I do not see an M10 needing that kind of fuel.

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2 hours ago, thewheelerZ said:

Another dumb question, is this any different than a normal surge tank?  Why the switch to the reserve tank (maybe I dont understand where this reserve tank is stored).  We have a surge tank with a level sensor in it, once the tank starts to drain a light is triggered on the dash that says PIT NOW, you have a basically a full lap worth of fuel.  Same idea, just no extra switch.

 

What kind of level sensor do you have? Did you mod a aftermarket one?

 

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Neat idea, i like it.

 

We put a 10psi check valve from our lift pump to our surge to ensure 10psi on our lift pump, when that drops we know we have only .5 gal of surge tank left and need to get to pit lane. 

 

You should post the finished product i bet thered be some serious interest. 

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3 minutes ago, Gkuhn41 said:

Neat idea, i like it.

 

We put a 10psi check valve from our lift pump to our surge to ensure 10psi on our lift pump, when that drops we know we have only .5 gal of surge tank left and need to get to pit lane. 

 

You should post the finished product i bet thered be some serious interest. 

I like that idea as well. Simple is good. 

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2 minutes ago, turbogrill said:

 

aha nice. and you just cut the existing surge thank?

 

Does the needle jump alot? 

Yeah exactly, hole in top of surge tank.

 

No needle, the one we have doesnt provide a level.  Its a simple float that trips a switch if it drops a certain amount (a touch over an inch if I remember correctly) and the switch turns on a light on the dash.  Light never comes on during normal operation (with gas in the tank!).

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