surge tank set up.

[Fish]

with your surge tank you'd want about a 1L.

With my setup i am running a 100GPH carter pump (also 7psi) and it and the fuel rail return to the tank. I was going to have the rail retain to the surge and have the pump back up on itself. Not a good idea i was told. so got a -6 T peice and now both lines return to the tank.

(this setup is untested)

A VL/Camira EFI pump is a bosch pump. Are you saying bosch pumps are crap?

[4SFED]

Definitely run the fuel rail back to the surge tank and then an overflow back to the main tank. If you don't do this your asking for serious potential issues:

Lift pump is bigger than main pump: your lift pump will be pumping into a tank that is already full and the pressure build up will be massive as there will be no way to regulate this (like 100psi!!) - this will kill the lift pump eventually and maybe even spilt your lines/tank and cause a massive fuel leak.

Main pump is bigger than your lift pump: your surge tank will eventually drain itself dry and you will have massive fuel starvation problems.

Bottom line - set it up with a rail return / overflow and save yourself the potential massive issues.

[EVOSTi]

4sfed, i dont think anyone mentioned not running a return from the surge tank.

secondly, you wouldnt get 100psi fuel pressure in your surge tank unless you were using a high pressure fuel pump as a lift pump. noone has suggested this as its obviously stupid. most lift pumps are between 4 and 7psi.

and finally its pretty obvious you want a lift pump that supplies more fuel than the main pump.

[4SFED]

4sfed, i dont think anyone mentioned not running a return from the surge tank.

yep your right - i misread one of the posts.

secondly, you wouldnt get 100psi fuel pressure in your surge tank unless you were using a high pressure fuel pump as a lift pump. noone has suggested this as its obviously stupid. most lift pumps are between 4 and 7psi.

This is a very very common setup - running a main efi pump as a pre pump - i do it and probably 75% of the guys i know are also doing it - why is it so obviously stupid?

and finally its pretty obvious you want a lift pump that supplies more fuel than the main pump.

Ideally yes, but not essential at all. I run a single small efi pump as my pre pump and then 2 whopping great main pumps and i know that my prepump will probably only supply about a quarter of my main pumps capacity. I would have to completely empty my surge tank for this to become a problem, and for that to occur i would have to be on full throttle, full boost for a stupid amount of time. Your only emptying your surge tank at the rate that your engine is using the fuel, anything else is overflowed back into the tank. For anyone to empty a 1 or 2 liter tank, with the lift pump filling it up constantly, you would have to be making like 800hp for a few minutes. Not a real issue in most cases. But if you are making 800-odd HP then your right, a setup such as mine is probably not the best option and you would want to do it slightly different.

[4SFED]

4sfed, cant you get a lift pump that flows enough fuel thats still low pressure? would be better imo, especially if its in cabin.

I am sure you can - one of the massive holleys or something can do it. You will pay pretty big $$ for these, and in comparison a small(ish) efi pump is dirt cheap. either way it doesnt matter as any excess flow is still only going back into your main tank, so weather the pump is high or low pressure, its kinda irrelevant.

and re lift pump flowing more than main pump, i spose its only essential if youre not returning to the surge, as in my case. but like i said, in my case with my setup, it was found that returning to the surge was causing the fuel pumps to fail.

I have never heard of a problem such of yours, and i definitely don't know of anybody running it the way your running it, but if it works for you then thats all that matters. And your right, in 99.9999% of setups (returning the fuel to the surge tank) the size of the pre pump is less critical.

[The Real Roadrunner]

I am sure you can - one of the massive holleys or something can do it. You will pay pretty big $$ for these, and in comparison a small(ish) efi pump is dirt cheap. either way it doesnt matter as any excess flow is still only going back into your main tank, so weather the pump is high or low pressure, its kinda irrelevant.

i tend to disagree slightly on this one.
whilst i have setup surge systems on cars using efi pumps as a lift pump i only do it if the tank was efi to start with.

reason being why buy a low pressure if there is already an adequate intank one.
if i setup one from scratch i always use a low pressure outside the tank as efi pumps dont really like to suck fuel to much as they would rather be gravity fed.efi pumps can cavitate if they're to high from the bottom of the tank and that in itself will cause probs/burnt out pumps.

a holley is around the $200 dollar mark and with no pressure against it will outflow an 044 or two with ease.

$200-250 lift pump vs $4k engine build, i know which way id go.

cheers
linden

[4SFED]

if i setup one from scratch i always use a low pressure outside the tank as efi pumps dont really like to suck fuel to much as they would rather be gravity fed.efi pumps can cavitate if they're to high from the bottom of the tank and that in itself will cause probs/burnt out pumps.

completely agree! The only reason i can get away with using an efi pump as a pre pump is due to the fact that it sits lower than the tank AND the fuel is picked up directly out of the bottom of the tank - so its always being fed fuel through gravity. I should of stated this bitin my replies - my bad

[Fish]

i would also be worried of using a efi pump to fill a surge tank. fuel will faom and that will lead to lean outs.

[NeoNasty]

Crap really?

I always figured that Id run the standard Vn commodore pump to a surge tank and from there run the higher capacity pump from that.

Oh well. I'll just upgrade the intank pump and be done with it. I doubt I'd need a surge tank.

[The Real Roadrunner]

Crap really?

I always figured that Id run the standard Vn commodore pump to a surge tank and from there run the higher capacity pump from that.

Oh well. I'll just upgrade the intank pump and be done with it. I doubt I'd need a surge tank.

you can run the standard intank to a surge with no probs at all, ive done it on many occasions and because its feeding from low in the tank it should be fine.

if you dont need a surge tank (no track work), i would just upgrade the factory intank but keep in mind that if you throw the car around with less than a 1/4 tank it may surge.

cheers
linden

ps ive never had a foaming issue and if the surge is the right size it would just go back to the main tank when you straighten the car up and the surge fills

[YLD-16L]

i would also be worried of using a efi pump to fill a surge tank.

My car has been using an EFI pump to fill the surge tank for the past 7 years or so and it's never been an issue, still on the same pump too. The pump is gravity fed though and it sits level with the base of the tank.

It's never surged under any conditions, street or track.

Fuel is pretty hard to foam and even if you do get it to foam it's so thin that it reverts back to normal almost instantly.

[Billzilla]

FWIW, how to build a swirl pot properly.

[30psi 4agte]

My car has been using an EFI pump to fill the surge tank for the past 7 years or so and it's never been an issue, still on the same pump too. The pump is gravity fed though and it sits level with the base of the tank.

It's never surged under any conditions, street or track.

Fuel is pretty hard to foam and even if you do get it to foam it's so thin that it reverts back to normal almost instantly.

FWIW
I have also been using a EFI pump ( VL) to fill my serge for 8 years now. The only down side i see is that you do have to have the pump sit low so that it has a gravity feed. This can cause issues with groung clearence on some cars/ tank setups.

I also run my return line back to the surge tank and havent had any probs with that either. Thats not to say in some cases where the fuel lines sit close to a heat source like the exhaust that running it back to the main tank could be of advantage.

[ed]

Your only emptying your surge tank at the rate that your engine is using the fuel, anything else is overflowed back into the tank. For anyone to empty a 1 or 2 liter tank...

...it would only take a v8 running 500cc injectors, running at 80% duty cycle, approx 20sec of WOT driving to completely empty a 1L surge tank

[4SFED]

...it would only take a v8 running 500cc injectors, running at 80% duty cycle, approx 20sec of WOT driving to completely empty a 1L surge tank

OK - i trust your maths, but even "only" 20secs is a hell of a long time to be on WOT in any one, continuous shot. After 20 secs you are doing some ridiculous speed so in anything but a dedicated track car (and even then i am not sure of too many tracks that will allow WOT for 20 secs continuous) its just not really going to happen. And if you do have a dedicated track car, then you would want to go about the fuel setup in a slightly different way than for a street-based car to take these kind of factors into account.

EDIT: if my maths is correct, for this V8 to use 1L in 20 secs it would have to be making around 600hp (using 5cc per min per hp), so to be on WOT for 20 continuous secs on a car making 600hp you would be doing like warp 5...... that is V8 Supercar kinda territory and we all know the lengths these guys go to in not only the fuel system but every aspect of the car...