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Discussion Starter #1 (Edited)
Hi,

This is my first post on M5board.
This forum really help me but i never post before.
I am french, i'm doing my best but forgive my bad english !

My girl friend and me, we are M lover :).
Currently we have a M3 46, a M5 60 and a M5 e39.

Let me present my M5 e39...












I hope you love it !

I have done lots of modifications:
- Heavy diet program (the cars weight is approx 1350 kgs).
- Full SS exhaust (header, decat, ...).
- Alpha N map (430 hp).
- AP racing front big brake.
- Custom suspension.
...

My todo list:
- find a solution to avoid fuel break after a big corner (not sure of this sentence !).
- Roll bar cage
- Porsche cayman S rear calipers.
- Hydraulic handbrake

Any suggestion to find a way to avoid the fuel issue after a corner ?


Regards,
 

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There are three good common, and one mediocre solution to the fuel cut issues.

My recommended option would be to use one or two low pressure "pickup" pumps to move fuel from the OEM tank to a new 4 liter tank that is taller than it is wide that you can buy/construct. In this tank, you'll have a new high pressure fuel pump that can deliver the appropriate pressure to the engine. The pick up pumps will keep this secondary tank (generally called a swirl pot) full no matter what, and even if it didn't, you have 4 liters of fuel in there. I like this solution because you're not fighting the flow of fuel from one side of the car to the other, you're just keeping enough fuel around the high pressure pump that it doesn't matter. There isn't a sweeper in the world long enough to drain 4 liters of fuel.

Another good/common way is to get rid of the factory fuel tank and install a fuel cell. This is probably the most expensive option.

Another option would be to cut the OEM fuel tank open, clean it out, weld in baffles in order to keep fuel in the two outside corners, and then use 2 "pick ups", one in each location, that have ball valves so that if they were to be in air, they would close.

The fourth, and less ideal option is just to always run with a full tank of gas. Yes, it adds a lot of unnecessary weight, but it is by far the cheapest and easiest solution.
 

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Discussion Starter #3
Thanks for you answer.

My issue occurred when the fuel level is under the middle, so it happen very quickly !

I have tried to put another fuel pump in the other side of the tank, it works but the gauge do not like it...

I think i will do your first solution (in french we call this a buffer tank), i would like to keep the OEM pump in the tank to fill the buffer tank. Is it possible ?
I don't now how swap the OEM pump to a low pressure one...
 

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Thanks for you answer.

My issue occurred when the fuel level is under the middle, so it happen very quickly !

I have tried to put another fuel pump in the other side of the tank, it works but the gauge do not like it...

I think i will do your first solution (in french we call this a buffer tank), i would like to keep the OEM pump in the tank to fill the buffer tank. Is it possible ?
I don't now how swap the OEM pump to a low pressure one...
Yes that will work, Just be sure to have an appropriately sized return line back to the fuel tank at the very top of the "buffer tank".
 

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A 4-liter swirl pot?! Wow. I thought I was excessive with a 1-liter swirl pot!

This is a real quandary with the E39 because the under-seat location of the fuel tank is ideal, but the fuel flow arrangement with the siphon pump on the driver's side is far from ideal. My solution has been to do both: swirl pot in trunk with two Bosch 044s in it and an ATL fuel cell under the back seat with two stock lifter pumps running PWM. It's overly complex and expensive, but it works.

--Peter
 

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Another option would be to cut the OEM fuel tank open, clean it out, weld in baffles in order to keep fuel in the two outside corners, and then use 2 "pick ups", one in each location, that have ball valves so that if they were to be in air, they would close.
Isn't the OEM tank plastic? That would be a bear to modify and get back together without leaking.
 

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4 liters is a probably excessive. I think 1 liter is somewhat common, but a bit depends on consumption. I generally believe 1/2 gallon (~2 liters) for ~400 or so hp is appropriate in the "never going to have to worry about it not being enough" way.

Figure a moderately efficient engine will consume about half a gallon of fuel at max power in about a minute (180 lbs/hr used as reference, note, I'm not familiar with S62 fuel consumption rates). Now, you won't ever be at max fuel consumption for an entire minute while also sustaining high lateral G's (except for maybe as an experiment on a skidpad). So 1 liter will work, but I wouldn't call it excessive, and a obviously this also depends on the design/shape of the swirl pot.

And I had no idea the stock fuel tank was plastic... Strange. Definitely eliminates that option.

And one other thing to the OP. The car looks great, but the seatbelt mounting is a bit dangerous due to the possibility of compressing your spine in the event of a crash. i would try to build a legitimate harness bar accross the rear to mount the belts to. The rollbar/cage you're planning would be a good solution as well.
 

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No photo of your girlfriend ? ? ;)

Only joking !!

Great first post and welcome to the forum !
 

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Great to see another E39 M5 track car....nice work.
 

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Great pictures. Thanks for sharing.

I often think how cool it would be to put my car on the track and it is nice to see so many people on the board doing just that.

Good luck with the future mods.
 

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Discussion Starter #14 (Edited)

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Discussion Starter #18
Nice!

Love the door panels on the E39 M5. I am in the process of making some. You didn't save your cutting pattern did you? Only real question is where to locate the door handle.

--Peter
I will do some photo for you.
I have not the cutting pattern, but if your need it, i can do it for you :).
 

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I will do some photo for you.
I have not the cutting pattern, but if your need it, i can do it for you :).
Thanks. If not already in existence, don't go to the trouble, as I will do it when I have the panels watercut. I would love to see more photos of the interior. Mine is gutted as well and weighs roughly 3100 lbs. dry without supercharger and FMIC. Trying to get to 1350 Kg/3000 lbs. WITH supercharger and FMIC.

--Peter
 

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Discussion Starter #20
Some pics to see why this car is so light :)

Carbon hood:


Logo light version :):


Carbon sun roof:


Rear light close system:


remove useless things:




light front door:


light interior:



light rear door:


rear seats:



:)
 
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