Winter Project - Fuel Cell
11-27-2008, 04:45 PM
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Winter Project - Fuel Cell
I have been considering to put a fuel cell in my track car for a number of years now.
I have decided to take the plunge though. I have had a struggle with my current (standard, but modded) tank for a number of years.
Completely standard the tank is actually pretty good, but the moment you start reducing all of the standard overflow and venting stuff, have to adapt the filler due to the safety cage, and start pulling more G's in corners, that is when the limitations show.
And off course there are band-aids. Fuel supply at higher G corners and contents below 10 L (2 gallon) was solved by putting in 40 L of tank foam. Slow refuelling was fixed by making extra venting valves, and changing the fuel ducts and caps.
But, as it is with band-aids, they are just that: Temporary fixes. Time for a more permanent solution.
The best solution IMO has already been invented: the Kokeln Fuel Cell
It takes in 27 gallons, cleans up the underbody airflow, fits in the stock position. At its original pricepoint USD 1600 - 1800, I would probably have gone for it.
But the current price, USD 4400 is really prohibitive.
Before I have it here in the Netherlands and installed in my car it will be over EUR 5000.
This could almost buy you a 951, not a nice one though, and certainly not mine.
Too rich, even for my taste.
So that leaves two alternatives: Having a Fuel Cell custom made, or using a setup based on a standard Fuel Cell.
One thing is clear: It has to be a large one, equal or bigger than the standard fuel tank. Under race conditions the car uses up to 80L per hour. If I would move to E85 it would be 100L/h, and a race is normally 35-40 minutes.
Last race of the season the car stumbled over the finish, which is exciting, but excitement that could be done without.
So step one, we took a cutting tool and opened the floor, to see how much space we could make in the back
Three of the problems are staring us in the face: The bell housing, the gearbox mounting and the shift lever.
The standard fuel tank is cleverly shaped to make optimal use of the space available.
But if you would want to put in something plane and straight, there is only a bit less than 10 cm ( 4") to work with, up to the original floor level.
On a lower level there is problem 4: The gearbox itself. That means, a Fuel cell has either to go behind the gearbox support, possibly even behind the gearbox, or has to go up.
From a weight distribution point of view, this is choosing between two evils: Either the center of gravity goes up, with an increase of roll, or the COG goes to the rear, increasing the inertia and hindering the turn-in behavior.
Looking the other way we are confronted with problem 5: The roll cage
The roll cage has been shaped in a way that the rear support is behind the existing fuel tank.
This is not per se required, but it makes me feel safe. Well, depending on how safe you can feel, driving a racing car.
But with the cross as low as this, the fuel cell cannot go up.
Well, no easy choices. Time to think.... (to be continued)
I have decided to take the plunge though. I have had a struggle with my current (standard, but modded) tank for a number of years.
Completely standard the tank is actually pretty good, but the moment you start reducing all of the standard overflow and venting stuff, have to adapt the filler due to the safety cage, and start pulling more G's in corners, that is when the limitations show.
And off course there are band-aids. Fuel supply at higher G corners and contents below 10 L (2 gallon) was solved by putting in 40 L of tank foam. Slow refuelling was fixed by making extra venting valves, and changing the fuel ducts and caps.
But, as it is with band-aids, they are just that: Temporary fixes. Time for a more permanent solution.
The best solution IMO has already been invented: the Kokeln Fuel Cell
It takes in 27 gallons, cleans up the underbody airflow, fits in the stock position. At its original pricepoint USD 1600 - 1800, I would probably have gone for it.
But the current price, USD 4400 is really prohibitive.
Before I have it here in the Netherlands and installed in my car it will be over EUR 5000.
This could almost buy you a 951, not a nice one though, and certainly not mine.
Too rich, even for my taste.
So that leaves two alternatives: Having a Fuel Cell custom made, or using a setup based on a standard Fuel Cell.
One thing is clear: It has to be a large one, equal or bigger than the standard fuel tank. Under race conditions the car uses up to 80L per hour. If I would move to E85 it would be 100L/h, and a race is normally 35-40 minutes.
Last race of the season the car stumbled over the finish, which is exciting, but excitement that could be done without.
So step one, we took a cutting tool and opened the floor, to see how much space we could make in the back
Three of the problems are staring us in the face: The bell housing, the gearbox mounting and the shift lever.
The standard fuel tank is cleverly shaped to make optimal use of the space available.
But if you would want to put in something plane and straight, there is only a bit less than 10 cm ( 4") to work with, up to the original floor level.
On a lower level there is problem 4: The gearbox itself. That means, a Fuel cell has either to go behind the gearbox support, possibly even behind the gearbox, or has to go up.
From a weight distribution point of view, this is choosing between two evils: Either the center of gravity goes up, with an increase of roll, or the COG goes to the rear, increasing the inertia and hindering the turn-in behavior.
Looking the other way we are confronted with problem 5: The roll cage
The roll cage has been shaped in a way that the rear support is behind the existing fuel tank.
This is not per se required, but it makes me feel safe. Well, depending on how safe you can feel, driving a racing car.
But with the cross as low as this, the fuel cell cannot go up.
Well, no easy choices. Time to think.... (to be continued)
11-27-2008, 06:18 PM
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Hans get a pre-fabricated fuel cell from ATL.
Have a look at one of their press releases here: http://www.atlltd.com/112008.pdf and there website here: http://www.atlltd.com/. They are all FIA approved and questionably the best on the market
all be it a bit on the expensive side but that will help with scrutinising.
They are based in the UK in Milton Keynes so shipping will not be an issue either. I suggest you give them a call with you specification etc.
Have a look at one of their press releases here: http://www.atlltd.com/112008.pdf and there website here: http://www.atlltd.com/. They are all FIA approved and questionably the best on the market
all be it a bit on the expensive side but that will help with scrutinising.They are based in the UK in Milton Keynes so shipping will not be an issue either. I suggest you give them a call with you specification etc.
11-27-2008, 06:21 PM
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11-27-2008, 06:32 PM
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11-27-2008, 08:42 PM
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11-27-2008, 10:09 PM
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Duke - He is best purchasing the fuel filler plus dump can and then fabricating a custom tank out of Aluminium and then fitting a cell bag inside - This is the option I'd go for unless he can get a retro pre built tank from them. At the end of the day the trunk of a 951/2 offers alot of space and it needs to be ideally behind or above the rear diff.
If he builds one himself then he may not get throught testing for racing which is what his great car is all about.
For safety though I'd rather go for a retro pre built option.
Ideally a tank that would fit in the spare wheel well would be best I recon.
If he builds one himself then he may not get throught testing for racing which is what his great car is all about.
For safety though I'd rather go for a retro pre built option.
Ideally a tank that would fit in the spare wheel well would be best I recon.
11-27-2008, 11:52 PM
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Hans - I have just had a look at your pictures again ... Do you remember the old TVR 350i's and 400SE's?
They had 2 fuel tanks either side of the diff or in our case the transaxle. To help lower the center of gravity I think this same setup would be the way forwards. All you need is a cross over pipe to connect each tank and then weld a blanking panel over the top for ultimate fire safety.
This will help reduce fuel slap and hence provide a greater fast corner change without upsetting the handling. The question is how wide would the cross over pipe need to be for rapid pit dump can fueling - Just an idea
They had 2 fuel tanks either side of the diff or in our case the transaxle. To help lower the center of gravity I think this same setup would be the way forwards. All you need is a cross over pipe to connect each tank and then weld a blanking panel over the top for ultimate fire safety.
This will help reduce fuel slap and hence provide a greater fast corner change without upsetting the handling. The question is how wide would the cross over pipe need to be for rapid pit dump can fueling - Just an idea
11-28-2008, 04:57 AM
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Next thing we did was look into a custom design
A custom design has two advantages: It could be made with a low COG, and it can have an internal catch tank.
This way, only one fuel pump is needed, and fitting it to the rest of the car is very easy.
As you can see in the pictures above, all fuel lines are steel braided teflon lines with AN fittings.
The rough design we came up with is a simplified version of the Kokeln unit.
It has three (virtual) shapes: On the right a part is slanted, the other lowered, which would create a natural lowest point for the fuel to be in, once the level drops.
The internal catch tank would be in this part, and the pickup and filler on the top.
The middle one is shaped so it can cover the gearbox and take optimal advantage of the space above.
The right one was kept flat, to leave enough space for the exhaust.
In fact, I do not want the exhaust to be there at all, but that is yet again another project.
The dimensions are rough estimates, possibly the height has to be a bit less.
The content this way would be 95 L, not bad at all!
It would fit behind the gearbox mounting point, so it would be more to the back of the car, compared with the standard tank.
But then: the price. Initial estimate is that a fuel cell like this would cost something like €2200, excluding the box, which would cost something like €300.
Cheaper than te Kokeln unit, but still....
That leaves the option to us standard fuel cell (or cells) .
To be continued....
A custom design has two advantages: It could be made with a low COG, and it can have an internal catch tank.
This way, only one fuel pump is needed, and fitting it to the rest of the car is very easy.
As you can see in the pictures above, all fuel lines are steel braided teflon lines with AN fittings.
The rough design we came up with is a simplified version of the Kokeln unit.
It has three (virtual) shapes: On the right a part is slanted, the other lowered, which would create a natural lowest point for the fuel to be in, once the level drops.
The internal catch tank would be in this part, and the pickup and filler on the top.
The middle one is shaped so it can cover the gearbox and take optimal advantage of the space above.
The right one was kept flat, to leave enough space for the exhaust.
In fact, I do not want the exhaust to be there at all, but that is yet again another project.
The dimensions are rough estimates, possibly the height has to be a bit less.
The content this way would be 95 L, not bad at all!
It would fit behind the gearbox mounting point, so it would be more to the back of the car, compared with the standard tank.
But then: the price. Initial estimate is that a fuel cell like this would cost something like €2200, excluding the box, which would cost something like €300.
Cheaper than te Kokeln unit, but still....
That leaves the option to us standard fuel cell (or cells) .
To be continued....
11-28-2008, 06:35 AM
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did you consider loosing the rear muffler ???just have one under the torque tube and exhit the exhuast next to trans axle .
you are well on the way Hans it looks awsome.
you are well on the way Hans it looks awsome.
11-28-2008, 11:07 AM
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Keep going HANS I'll bet on ya . I'm completely confident that in this part of the world if i sullied good drawings to a laser cuter i could have one custom fabbed for less than 2800 US and If Hans welds it him self he will swing it for under 1000 us
