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Fuel... To Sump or not to Sump.
Angel Acevedo - 4/5/20 at 03:25 PM

Topic started to fix a mess.
I mistakenly replied to a thread in the For Sale section thinking I was on this forum.
The following was copied from said thread.

I used the search function and went back two years without finding exactly what I wa looking for,
I am kind of hijacking this thread to keep it topic related.
I am buildiing a +442E (I think)with a 5.0 V8 engine.
Taking advantage of Lockup, I am working on my fuel tank, it is a sixty something liter alloy tank built fromwhat I had available, 3 mm checkered ali plate.
I have decided upon most of their features now, but I got to the sump.
I am deadset on using a sump, I had the size figured out to have a 1 lt sump but I c0cked up the measurments (Doh...! I skipped the CAD... and my sump came in at 650 mililiters, where I wanted 1 liter. I will be using a Low pressure pump to feed a 1 lt (I think it looks like a 1.5 lt) swwirl pot to feed a high pressure pump.

Questions
- Would 650 ml would be OK for this setup?
- Should I go for 1 lt tank sump?
- I have a chassis member that wonŽt let the hose pass straight to the location where the Low Pressure Pump will fit so I have two choices, make a hole in such member and weld in a piece of tubing for the hose to pass through, or run an internal pipe from the bottom of the sump to the side of the tank next to the Low pressure pump?
- Or do I forget about all the hassle and ditch the Low Pressure Pump and swirl pot and use only the High pressure pump feeding from the Tank Sump. Drawback to this is that IŽll have High pressure fuel running all the way through the transmission tunnel

For tank fittings, I am using turned bits of 12 mm ali plate that will be drilled and tapped appropriately.
Thanks in advance.


Related threads:
http://www.locostbuilders.co.uk/viewthread.php?tid=215241

http://www.locostbuilders.co.uk/viewthread.php?tid=215303

http://www.locostbuilders.co.uk/viewthread.php?tid=213998

Sorry for the inconvenience and thanks for your comments in advance...
AA


JAG - 5/5/20 at 07:23 AM

I'd just run a high pressure pump from the 650ml sump in the fuel tank.

Yes - you'll have high pressure fuel running through the transmission tunnel but I don't think that's such a problem (I have the same on my car). High or low pressure you've got to make sure it's sealed properly and also fit an inertia switch to protect in case of an accident etc...

Many current production cars have this set up.


Angel Acevedo - 6/5/20 at 03:32 PM

quote:
Originally posted by JAG
I'd just run a high pressure pump from the 650ml sump in the fuel tank.

Yes - you'll have high pressure fuel running through the transmission tunnel but I don't think that's such a problem (I have the same on my car). High or low pressure you've got to make sure it's sealed properly and also fit an inertia switch to protect in case of an accident etc...

Many current production cars have this set up.



Thanks.
Now that we are at it, would it be better 1 lt? or 650 ml??
My tank is not welded yet.
Thanks again.


Angel Acevedo - 6/5/20 at 04:36 PM

quote:
Originally posted by JAG
I'd just run a high pressure pump from the 650ml sump in the fuel tank.

Yes - you'll have high pressure fuel running through the transmission tunnel but I don't think that's such a problem (I have the same on my car). High or low pressure you've got to make sure it's sealed properly and also fit an inertia switch to protect in case of an accident etc...

Many current production cars have this set up.



Thanks.
Now that we are at it, would it be better 1 lt? or 650 ml??
My tank is not welded yet.
Thanks again.


obfripper - 6/5/20 at 04:58 PM

If you feed the fuel return into the sump you should have no starvations issues with the 650ml sump, the bypass flow back to the tank is far greater than the injected amount for most engine setups. If the bypass flow is returned to the top of the main tank, it will empty the sump when the fuel level is low during cornering.

I don't have a sump, just an L-shaped internal swirlpot with 3 viton rubber umbrella valves in the base. Just jiggling the swirlpot in an inch of fuel will fill the pot with fuel (approx 9 inches deep) due to the action of the valves, and my bypass return is into the pot as well which also helps to keep the pot full.

I have the high pressure lines running to the front, the only reservation i have about them now is they are Kunifer (Copper/Nickel alloy) and it is partially reactive to biofuels (marginal at E10, certainly at E85 levels). This doesn't seem to be a problem so far, but the bio content in our normal petrol is only going to increase.

There is plastic fuel line available that is certified for E85, so if i was starting from scratch i would buy the tool for fitting the couplings and use plastic pipe, or use stainless lines if a suitable type is available.
Another possibility is using stainless braided ptfe hose, but a run that long will not be cheap.

Dave