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Fuel Tank EFI Questions


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#1 _lj chev_

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Posted 10 March 2007 - 11:09 AM

Hey guys,
im in the process of fitting a rb30et into my lh and im after some thoughts and help as to what people do with thier fuel tanks with an efi engine?

Im wanting to put in a new fuel tank because im worried the standard one has rusty crap and particals in it which i dont want. but i dont want a drop tank because im after the sleeper look.

the fuel will be sucked out by a lift pump into a surge tank. what equations are to be done to work out surge tank size and fuel pump size?

the engine will hopefully making decent power so baffles are a must also im guessing?

Any thoughts and help wound be much appriciated.

cheers ryan

#2 _why-psi_

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Posted 10 March 2007 - 02:29 PM

i was going to do the same conversion so i set up my EFI pumps in the boot.

holley blue lift pump, surge tank and VL main pump

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#3 _why-psi_

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Posted 10 March 2007 - 02:37 PM

i used the standard tank and just soldered an extra fitting for a return line into the ring the fuel sender is mounted to. probably wont need baffles if u have a big enough surge tank
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#4 _lj chev_

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Posted 10 March 2007 - 03:46 PM

thanks heaps for the pics. very nice looking set-up and car you got there:)

did you have the fuel tank cleaned out or anything before hand?

what sort of motor are you running?

what fuel lines are you running to the engine?

i was thinking of running 044 bosch pump with 3/8 fuel line and using original line as fuel return aslond as its not too small.

#5 _why-psi_

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Posted 10 March 2007 - 05:43 PM

thanks :) . i didnt clean the tank out but probably should of. i got a filter after the lift pump so na craps gonna get into the surge tank. at the moment im running a 202 with triple SU's so had to turn down the fuel press from 50psi to 4psi lol. im running the original line and another the same size as a return

#6 Toranamat69

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Posted 10 March 2007 - 07:23 PM

I use a very similar setup in my LX and I didn't clean out the tank until I managed to burn out 2 VL pumps in the first 3 weeks - Then I cleaned the tank and it hasn't re-occurred for the last 3 1/2 years - at $250 a pump I would clean the tank.
I am using, and always have been using a 10 micron filter straight out of the tank before the first pump but the really fine shite that got through took down my pumps and I found it when I pulled them apart.

Holley blues are the noiseyest POS in the world and they should stop selling them, you will kick yourself from now till the end of time if you install one.

I have a 2.1L surge tank and if my tank is under 1/3 full, I get fuel surge and engine missing on hard corners on the track - Never notice it on the street though so after all that farting around, I would advise a custom baffled tank with an in tank High pressure pump - no external pumps, no external surge tank, just the feed line, the return and a 10 micron filter hidden away somewhere.

Simpler, lighter, cleaner, quiter and will work better and with what I have spent, I could now have that sytem.
As it is, I now have all that $$ and work still to spend.

I'm not bitter am I :cry:

One of those hard lessons in life.

M@

#7 _why-psi_

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Posted 10 March 2007 - 09:07 PM

holley pumps are noisy!

my car sounds like a fishtank

#8 _Chaotic_

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Posted 11 March 2007 - 05:57 PM

In the skyline i run a Bosch 040 intank pump rated to something like 500+ hp. Its quiet and never had any dramas, i recommend it. Can be had for about $200 as well.

#9 _nunganunga_

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Posted 11 March 2007 - 08:22 PM

Toranamat69 is making sense. If your using a commodore engine, why not adapt a commodore fuel system to the torana? VL is okay but VR is better. Shiny things in the boot are good for the impression ratio but thats about it(opinions may vary).

#10 _why-psi_

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Posted 11 March 2007 - 10:54 PM

they arent only for looks. if you have no surge tank and your main tank isnt very full you can uncover the fuel pickup under acceleration/braking/cornering which means leaning out which is not a very good thing. dosent matter what fuel system you adapt, a surge tank is good to have. that way theres a constant healthy supply of fuel to the engine under all conditions.

#11 _nunganunga_

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Posted 12 March 2007 - 07:38 AM

If you have an in tank pump a swirl pot solves this problem.

#12 _why-psi_

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Posted 12 March 2007 - 05:09 PM

true. the more volume you can add to the swirl pot the better tho

#13 _QIKSLR_

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Posted 12 March 2007 - 06:31 PM

I have a 2.1L surge tank and if my tank is under 1/3 full, I get fuel surge and engine missing on hard corners on the track - Never notice it on the street though

So does this mean that you actually manage to drain the 2.1L surge tank on the track due to it not being able to pick up enough fuel while sustaining hard cornering? I'd have thought 2.1L would go a long way even in a really high performance motor? Does your fuel pressure drop?

Edited by QIKSLR, 12 March 2007 - 06:32 PM.


#14 _coupe202_

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Posted 12 March 2007 - 07:58 PM

In stead of using a holley fuel pump you can a small efi pump to fill the surge tank that if you go that way.
Ive got a 60lt fuel cell in mine with 2 bosch 044 mounted at the very bottom of the fuel cell.

#15 _LX_SS_

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Posted 12 March 2007 - 09:37 PM

keep in mind, that if u decide to run a surge tank, there must not be fittings of any kind inside the vehicle at all to make this legal.

correct me if i am wrong here, but arn't the torana fuel tanks able to be split ? if so whats stopping you splitting the tank, putting a fuel pump in with a swirl pot and some of that honeycomb weave in there, and modifing the sender house to suit a return line ???

Edited by LX_SS, 12 March 2007 - 09:38 PM.


#16 _QIKSLR_

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Posted 13 March 2007 - 09:03 AM

In stead of using a holley fuel pump you can a small efi pump to fill the surge tank that if you go that way.
Ive got a 60lt fuel cell in mine with 2 bosch 044 mounted at the very bottom of the fuel cell.

I thought the myth was that EFI pumps didn't like to be run dry, which was the whole purpose of having a surge tank with EFI in the first place?

#17 ls2lxhatch

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Posted 13 March 2007 - 09:49 AM

The purpose of the surge tank is to guarantee a constant fuel flow without air to the EFI pump which in turn guarantee's a constant fuel pressure to the engine. If the fuel pressure drops then the engine will run lean. If the fuel pressure drops at full throttle it could be terminal for the engine.

The only way you can guarantee fuel pressure at all fuel levels and G-Force loads is to have a surge tank system with sufficient capacity to provide fuel when the lift pump is sucking air.

A swirl pot is not suitable for the EFI pump but would help keep the lift pump from running dry.

#18 Toranamat69

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Posted 13 March 2007 - 05:47 PM

There are plenty of factory high performance cars out there with in-tank high pressure pumps which draw from an internal baffled section of their tank and suffer no fuel surge (kind of like an intank - surge tank anyway) so I am going to follow their lead.

I am also a very strong believer of the less is more method of building cars now - the fewer parts, the less there are to fail, the lighter it is (not many parts weigh less than air) and the easier it is to package.

M@

#19 ls2lxhatch

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Posted 13 March 2007 - 10:24 PM

I agree simpler is best. I wanted to fit a VZ Commodore fuel pump $250 which has a built in surge tank inside the swirl pot in my drop tank. You can buy weld in mount rings for the VZ pump from Castle Auto Electric. The problem is that they require a minimum depth of 240mm and 40mm clearance above the pump. My Brown Davis 120lt drop tank is only 210mm deep and has 5mm clearance above.

A point to note is that the Torana fuel tank is the worst possible design when it comes to fuel surge. The ideal tank is as deep, thin and narrow as possible with the pickup at the rear. The Torana tank is shallow, wide and long.

I am still looking for a fuel system for my drop tank. My current plan is to open up the tank and fit a swirl pot inside and modify the recess in the tank for the spare tyre to house a Bosch 044 pump. I will probably use a VL style pump to supply the surge tank. This will cost around $1000 so if you can come up with a simpler or cheaper option I would like to hear about it.

Edited by ls2lxhatch, 13 March 2007 - 10:25 PM.


#20 _lj chev_

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Posted 13 March 2007 - 10:29 PM

So with the custom tank with the surge tank and pumps inside are you going to be able to open it up incase a fuel pump is broken or for some other reasons?

i spose the tank will also need to be big in size to fit every thing so sorta puts it out off the equation for me cause i want the outside off the car to look standard.

is anybody making stock looking tanks that can be painted black?

wouldn't you (toranamatt) still have the same gear just located in a tank instead of spread out? how is it you are saving weight then?

thanks for the input guys:)

#21 ls2lxhatch

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Posted 14 March 2007 - 09:13 PM

The tank is a 120lt aluminium drop tank so is does stand out a bit.

The lift pump will bolt into the front of the tank in a similar maner to a VL Commodore. The EFI pump will be mounted on the outside of the tank in the modified spare tyre recess. The surge tank will have hard lines welded to the outside of the tank so there should not be anything inside that tank that requires servicing.

You could check whether mounting the surge tank in the engine bar is legal or not in your state. I think Litre8 has the surge tank and EFI pump in the engine bay.

http://www.litre8.com/neweng9.JPG

#22 _LX_SS_

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Posted 15 March 2007 - 01:44 PM

ls2lxhatch,

brown davies will make you a 60litre tank, with internal fuelpump, swirl pots, return lines on the tank, everything done for approx 1000 (think it came to 1035 or so) saves doing anything else.

has anyone ever thought of transplanting a vn- vy tank ??? just an idea

#23 Toranamat69

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Posted 15 March 2007 - 06:14 PM

wouldn't you (toranamatt) still have the same gear just located in a tank instead of spread out? how is it you are saving weight then?


Using the system on a 300ZX as an example (I like stealing some of their ideas) the surge tank built into the tank is plastic and would be lucky to weight 100g's.

If I used the same system, I would save the weight of 1xholley blue pump, 1xsurge tank (mine is stainless and approx 5kg), 1 fuel filter, approx 2m of stainless braided hose, the fuel to fill all of these items (approx 3litres) and about 5 or 6 fuel fittings to hook them all up.

I'd say I would have nearly 10kg saving there - maybe 7-8kg if the surge tank you were ditching was alloy. I also use 2 VL pumps so if I get 1 large one which can handle the flow of both then I will most likely save a bit more too.

The fuel pump is mounted under a bolted flnge in one unit with fuel level float so you can undo the flange and take it all out - this is standard on almost all EFI cars these days.

M@

Edited by Toranamat69, 15 March 2007 - 06:20 PM.


#24 _coupe202_

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Posted 15 March 2007 - 08:36 PM

You are right in what our saying QIKSLR that efi pumps dont like to be run dry, thats way the efi fuel pumps are at the lowest point of the fuel tank so they are gravity feed at all times.

#25 _the gts_

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Posted 15 March 2007 - 09:12 PM

I agree simpler is best. I wanted to fit a VZ Commodore fuel pump $250 which has a built in surge tank inside the swirl pot in my drop tank. You can buy weld in mount rings for the VZ pump from Castle Auto Electric. The problem is that they require a minimum depth of 240mm and 40mm clearance above the pump. My Brown Davis 120lt drop tank is only 210mm deep and has 5mm clearance above.


Are there any other pumps like the VZ that are shorter?
I am going to build an aly tank for my LX but its not gonna be a drop tank cos i dont have flares, gonna be tubbed




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