Fuel cell design - running lines from trunk to engine bay

[Mick]

I'm in the planning stages of installing a fuel cell and have a good idea of which parts I'll use, but I'm undecided on how to route the lines from the trunk to the engine bay.

Seems there are 4 options, all have trade-offs:
- Route braided line through the cabin
- Route braided line under the car (with Kevlar, TPE, or PVC sheath)
- Utilize existing hard lines by either brazing on AN fittings or using slip-fit AN adapters
- Run new hard lines

I'm leaning toward running braided under the car but would love to hear what others have done.

[jimmy p.]

Hey Mick,
I ran braided textile lines under the car, basically in the same pathway as the stock lines, down the driver side of the car and up into the engine bay along the left side of the bay.
Its been like that maybe almost 20 years. I didnt even use any fancy sheathing. I used some heater hose rubber sheaths I made up for areas I thought might get abuse, but never really did anything super fancy.
Its probably due for a PM rip it all out and re-do simply "because" but I wouldnt feel the least bit wary about racing on it this year, or next, or next.
I don't care what the fluid handling method is, I have never been a fan of the lines inside the car. No reason, just my own paranoia.

[Mick]

I have never been a fan of the lines inside the car. No reason, just my own paranoia.

Same here. I'll probably going to install an inertia kill switch as well.
What did you use for hangers under the car?

[jimmy p.]

Same here. I'll probably going to install an inertia kill switch as well.
What did you use for hangers under the car?

Lots and lots of these: https://www.amazon.com/Clamps-Assort...a-727285570440

Affixed to the body with nutserts. I love nutserts.
Overall I just love running plumbing and wiring. It might be my favorite thing.

[Mick]

Haha, and here I thought you did something fancy. If it works...

[jimmy p.]

Haha, and here I thought you did something fancy. If it works...

LOL hell no. Fancy isnt really in my SOP. I'm very much more the KISS kind of guy.

[HANDBLT]

Lots and lots of these: https://www.amazon.com/Clamps-Assort...a-727285570440

Affixed to the body with nutserts. I love nutserts.
Overall I just love running plumbing and wiring. It might be my favorite thing.

This post is worthless without pics!!! Let's see some race car shit. LOL

T

[evanboyle]

I am in the process of doing the same thing! My tank is an ATL well cell with 3-door surge tank and HP pump - Ordered from VAC over a year ago and now that I've noticed some serious fuel starvation below 1/2 full on the stock tank it is time to upgrade.

Question is - Should I still use an external inline Bosch 044 (I assume this would replace the stock inline HP pump) or is the on-board CFD-104 27gph/100psi pump sufficient?

Thanks for the tips for the -6AN line fasteners

[99M3Riverside]

Soooo, for those with a cell how does that effect weight balance of the car. I have been dealing with fuel starvation issues for a while. I was planning on just installing a swirl pot sourced from Ireland Engineering. I have contemplated just going for a cell but worried more about upsetting the car handling vs the actual cost.

[jimmy p.]

Think it will handle worse than a Gruppe A car LOL?
Thats exactly what they had.

I honestly didnt give it a thought.
I wanted a cell, I put it right where the Gruppe A cars had theirs, didnt worry about it a minute after that.
My plumbing is vastly simplified over the stock tank setup.
My PM and maint is vastly easier than the stock setup.
Car corner weights fine. RR is always still a little light because I use a super small battery. If I put a real battery in it it would get really close to where it would want to be.

[jimmy p.]

I am in the process of doing the same thing! My tank is an ATL well cell with 3-door surge tank and HP pump - Ordered from VAC over a year ago and now that I've noticed some serious fuel starvation below 1/2 full on the stock tank it is time to upgrade.

Question is - Should I still use an external inline Bosch 044 (I assume this would replace the stock inline HP pump) or is the on-board CFD-104 27gph/100psi pump sufficient?

Thanks for the tips for the -6AN line fasteners

I use one single 044 and its fine.
I have toyed with putting in a lift pump over the years because my Gruppe A car has one, but the way they (BMW Motorsport) mounted the fuel pumps the 044 was above the cell on the trunk floor.
I mounted mine below the cell nested up under the passenger side rear seat and I used a one way check valve to keep pressure in the feed line and to date (almost 20 years maybe) I have no issues.

I am guessing there is some math to derive if a single 27gph pump will support your engine.
When I installed my cell I spoke to one of the techs for the Bosch Motorsports main importer here in the US and he told me they use a single 044 up to about 700hp, then when cars get over 700hp, they just add another fuel line and another 044.

[evanboyle]

Thanks Jimmy! ATL claims their CFD-104 pump is good for up to 600HP. I suppose if the in-tank pump isn't sufficient I will add the 044 in the trunk or under the rear seat like you did.

BTW - do you mind sharing your plans for the ATL well cell hat box? I know my welder can fab something up but it seems like your setup has been dialed in and working well for a long time.

Cheers man - I owe you a beer


OP/Mick - Sorry to hijack your thread; Hoping some of my questions / comments are helpful for your build.

[Mick]

OP/Mick - Sorry to hijack your thread; Hoping some of my questions / comments are helpful for your build.

No problem at all, the more info the better.

[jimmy p.]

Thanks Jimmy! ATL claims their CFD-104 pump is good for up to 600HP. I suppose if the in-tank pump isn't sufficient I will add the 044 in the trunk or under the rear seat like you did.
BTW - do you mind sharing your plans for the ATL well cell hat box? I know my welder can fab something up but it seems like your setup has been dialed in and working well for a long time.
Cheers man - I owe you a beer
OP/Mick - Sorry to hijack your thread; Hoping some of my questions / comments are helpful for your build.

If they had that internal CFD-104 setup, that would support up to 600HP when I did mine I probably would have just bought that and been done with it.
It really is the easy button.

The downside of being on the front end of a product is that when I purchased mine, they had literally just released the Well Cell, they had no options for it, the internal black box I am using was a generic one they had in their catalog, I had to cut it into the foam myself. I initially installed the cell without anything, just a foam filled cell (that didnt work so well LOL).
I think mine might have been the first retail Well Cell the guy sold, I bought it direct from ATL, I don't think the dealers had even received the first shipments.

The hat box cover was the easiest part.
I just took the cell to a sheet metal fab shop that I know and asked them to build an 090 aluminum slip cover for it. 090 was the spec SCCA has for fuel cell enclosures in aluminum.
Mine has four simple flat stock arms coming off of it that are bolted through the trunk floor.
I could have sworn I posted pics of it somewhere but I'll be damned if I can find one.
Im at the airport now, working out of town for the weekend, when I get home I can take some.

Happy to answer any questions.
Cheers
jimmy

[1990m3]

I copied Jimmy's design but made a few changes. I actually did run AN fuel lines from the well cell through the rear bulkhead into the backseat area, then down under the car and followed the path of the factory fuel lines. I did this because I didn't want them to pass over the half shaft, in my mind a half shaft failure could cause a fire if it blew a fuel line. In hindsight it probably wouldn't have mattered and I should have made an aluminum shield to cover the lines in that area.

My fuel diagram is as follows:
- black box with the pickup in the well cell, I used a
- Facet low pressure lift pump to bring the fuel out of the well cell
- Delivered to Surge tank mounted under the car, surge tank has a Bosch 044 internal high pressure pump. It's a 034 motorsport surge tank
- Surge tank and pump feed the fuel rail
- Fuel rail returns to surge tank
- Surge tank overflow returns to well cell
- Return line strategically placed at the fuel pickup so in theory I can run it low.

It seems to work most of the time, but I don't spend a lot of effort measuring out fuel quantity. I can effectively run it down to about 1 gallon left before I feel some surging. The theory is that the surge tank with the high pressure pump is always feeding the motor so regardless of how much fuel is in the tank there should always be 1.5L of fuel in the surge tank to keep it running.

I have AiM data on my car and a fuel pressure sensor mounted at the inlet of the fuel rail, even at end of races when the fuel level is low I do not have any variation in pressure.

Dave