converting from single fuel pump to dual

[Liam]

It is true that a surge tank is not really the hot setup and kind of unnecessary.


Also true though is asubimmer talks a lot but he ain't saying much, kind of a common occurrence in forums like this.

[guibo09]

lol all I'm saying is it isn't needed in an e30. Go to the track and see how many e30's use a surge tank. I doubt you will even find one. If you want to waste your money on it then fine, its not like I'm paying for it. But hey if you do put one in then next time you smash your car you are gonna have to make up another reason why it wasn't your fault.

fuck off. never post in my threads again. thank you.

[guibo09]

It is true that a surge tank is not really the hot setup and kind of unnecessary.

But the type of pump you are looking for as a feeder can be found in older Volvo 240s. It is a Bosch unit ( I don't have the PN handy) , install it in place of the in-tank pump using the original pump "bracket".

These will not push through a filter well it will need to be located after the pressure pump.

what about keeping the current hi pressure pump as is? would there be any negative consequence?

[Liam]

I'm not sure what it is you are trying to achieve, are you using carbs rather than FI? .

[guibo09]

I'm not sure what it is you are trying to achieve, are you using carbs rather than FI? .

trying to achieve this basically:

http://www.sdsefi.com/techsurge.htm

[Liam]

Okay I see.

You really don't need this, the fuel system in the e30 is designed for high pressure, that is a workaround for a low pressure system that cannot flow the pressure and volume necessary for FI.

[guibo09]

Okay I see.

You really don't need this, the fuel system in the e30 is designed for high pressure, that is a workaround for a low pressure system that cannot flow the pressure and volume necessary for FI.

i know it is essential for a carb to FI conversion. but it also mentions how it can be useful for fuel starvation issues on a FI car.

the above diagram, is basically how most surge tanks work for FI cars anyway. im just wondering, if i use a high pressure pump in the tank instead of a low pressure one if i will run into any problems. i dont think so since the pump will not build much pressure without a FPR inline, but i have never tried it.

[Liam]

The reason for the low pressure in-tank pump and the high pressure external was because high pressure pumps wont draw very well. The latter system solved all the problems (better pump technologey).

With this system there wont be any fuel starvation problems (unless you are running out of fuel or have a 1000 hp blown V8 ).

[guibo09]

The reason for the low pressure in-tank pump and the high pressure external was because high pressure pumps wont draw very well. The latter system solved all the problems (better pump technologey).

With this system there wont be any fuel starvation problems (unless you are running out of fuel or have a 1000 hp blown V8 ).

what about on a long hard right hander that sloshes all the fuel to the left side of the tank away from the pump pick up? i dont care how good of a pump it is, it doesnt create fuel. and all it takes is for the pickup to be exposed to air for one second to suck in a bubble of air which eventually gets to the engine and causes a 1 sec fuel cut. there is nothing to bleed the air out of the line.

[Liam]

what about on a long hard right hander that sloshes all the fuel to the left side of the tank away from the pump pick up? i dont care how good of a pump it is, it doesnt create fuel. and all it takes is for the pickup to be exposed to air for one second to suck in a bubble of air which eventually gets to the engine and causes a 1 sec fuel cut. there is nothing to bleed the air out of the line.

The late model tanks have a baffle that the pump sits in, for the rally cars and lower end group cars we sometimes installed a deeper baffle, on Grand touring cars it's a whole different ball game (fuel cells and completely re engineered fuel systems, more for crashworthyness than anything else).

How hard are you really expecting to drive?

BTW Baffles are still available and are also a fairly simple and effective component.

[guibo09]

The late model tanks have a baffle that the pump sits in, for the rally cars and lower end group cars we sometimes installed a deeper baffle, on Grand touring cars it's a whole different ball game (fuel cells and completely re engineered fuel systems, more for crashworthyness than anything else).

How hard are you really expecting to drive?

BTW Baffles are still available and are also a fairly simple and effective component.

i do auto-x, which sloshes the tank like crazy. an example of a fuel cut prone situation was a complete right hand loop around a ~50ft circle. the loop lasts over 10 seconds and you are pulling alot of g on good tires.

do you suggest i just add more baffling? is this even possible without opening the tank?

[Liam]

i do auto-x, which sloshes the tank like crazy. an example of a fuel cut prone situation was a complete right hand loop around a ~50ft circle. the loop lasts over 10 seconds and you are pulling alot of g on good tires.

do you suggest i just add more baffling? is this even possible without opening the tank?

Baffle drops in right down the hole with the pump, best solution for the problem. But in order to starve the pump the tank would have to be nearly empty in something like a 2+ G turn (just a guess at the G #s)

[guibo09]

Baffle drops in right down the hole with the pump, best solution for the problem. But in order to starve the pump the tank would have to be nearly empty in something like a 2+ G turn (just a guess at the G #s)

okay this is very interesting. are you saying the stock late model tank requires a 2G turn almost empty to starve, or an extra baffled tank?

can you give more details on what kind of baffle i need, where to purchase or how to fabricate, etc?

[Liam]

okay this is very interesting. are you saying the stock late model tank requires a 2G turn almost empty to starve, or an extra baffled tank?

can you give more details on what kind of baffle i need, where to purchase or how to fabricate, etc?

2gs is probably an exaggeration, I just made that up.

The baffle is an aluminum tube about with about 10 6mm holes in the bottom OD rim (about 5mm up from the bottom) and a few more about 150mm above that tube was just the right OD to drop down the hole the fuel pump drops in (I can't remember the size at the moment) we actually ran the tube all the way to the top of the tank so the pump mount secured it to the bottom of the tank.

We also relocated the return line to drop the unused fuel to the top of the pump bracket ( bracket from the earlier cars, crazy huh).

[jlevie]

We also relocated the return line to drop the unused fuel to the top of the pump bracket ( bracket from the earlier cars, crazy huh)

You'd have done better to leave the return line where it is as I understand the construction of the tank. That return powers a syphon that lifts fuel from the left side of the tank and dumps it in the right side (where the pump is).

The only times I've seen E30's have fuel starvation issues on the track there were obvious problems with the tank (loaded with rust), pump, or filter.