High Output Fuel System

[Zuffen]

I'm in the process of building a fuel system to support around 600hp.

Starting at the tank I've had a sump installed with 2 x 1/2" outlets that will feed though 2 x 1/2"fuel filters into 2 Bosch 044 high performance pumps.

The pumps will run through 2 x 30amp relays wired directly from the battery (it's only 500mm away from the pumps).

I'm going to treat the engine like 2 x 4 cylinder engines by running 2 fuel lines (1 to fuel rail) with a balance pipe running to a Malpasi rising rate regulator.

My problem is sizing it all.

THe outlet of the Bosch 044 is via a banjo fitting that is only 5.3mm in diameter. This gives across section of 8.8 square mm. I find this surprisingly small to flow the 700hp these pumps are supposed to flow.

I plan to replace the banjo with something around 7mm which will give ma a cross section of 15.4 square mm which is looking much better.

I then plan on using fule line of around 9mm internal diameter. This allows for a little surface friction inside the rail.

The fuel line will enter the standard rails at the rear using 7mm bangos and the factory banjo bolt (which I've bored out to 7mm)

The front of the rails will be joined by similar sized banjos and fuel line.

One thought the inlet and outlet on the Malpasi is only around 5mm but it should be OK as a return.

All fuel line will be high pressure fuel line, but I'm not getting fancy with Earls fittings etc.

Can anyone tell me what I've missed or if I have it wrong?

 

[rms]

Rod,
You will probably require 2 pressure regulators.
We have a blown 2.2ltr VW on methanol, around 500bhp, 2 x 044 pumps and -6 lines. Uses 5.5ltrs/min on WOT. We had to fit a second FPR as the pressure was rising on part throttle. The single FPR could not return enough fuel.

 

[JustenGT8]

Similar setup to what i have Zuffen.

x2 Bosch 044 pumps fed individually from x2 1 inch lines out of the surge tank.

these feed straight into a speedflow T-piece and out into a -8 braided line.

-8 into the rail and x2 -6 crossover lines front and rear...all speedflow and no bangos.....yuck, hate bango fittings.

single AFPR and handles return just fine...can't recall brand off the top of my head but common top shelf Japanese brand (Malpassi are pretty average for EFI i have found?).

Not a hint of an issue up to 400rwkw and running a stupid 25psi boost ie. 68psi fuel pressure.

Braided line gives a light fuel odour if the car has been sitting for a while but that's my only small complaint

 

[Zuffen]

Errol,

I would imagine setting the two FPR's to be identical may pose a problem.

Certainly worth keeping in mind.

Justen,

As I don't have doors, windows or a roof the fuel odour will escape.

I always look at "T' peices and imagine fuel fighting itself with one (the more powerful as no two pumps are identcal) pump pushing fuel back up the other line.

Funny all my brake calipers use banjos, as does the master cylinder. I would prefer a banjo to fail on my fuel system as at least the car will stop!

 

[Hennie Marais]

what I did now and previously:
2 x walbro's running with twin 8mm ID fuel lines to the front, one for each rail then two 8mm returns to my A1000 aeromotive FPR(one on each side of the regulator) and then a 10mm ID return line. I've done this with the bosch pumps too with great success.

Get hydraulic fittings, they are cheap, work like your AN fittings with nice 90deg bends, I wouldn't go the banjo route on High performance cars.

 

[cribbj]

Always the contrarian, I'm not a fan of oversizing the fuel delivery system, because in doing so, you bypass enormous amounts of fuel at low output, which causes heating of the fuel, rapid evaporation, and loss of fuel density and power. To bypass enormous amounts of fuel, you have to have a ginormous single regulator, or twin regulators.

For my system I just use a single Supra pump and a single delivery line up to my 2JZ-GTE motor, then split the line to feed each end, with a center return, and a normal sized regulator.

With PWM technology, I control the voltage to the pump so that it's supplied with 8.5-9.0 volts at idle and cruise, 13 volts for light boost, and 16-17 volts for the occasional heavy boost. This setup is simple, works very well, and is good for at least 700 BHP.

Another benefit is that I haven't any objectionable fuel odors.

 

[JustenGT8]

Rod, your brakes aren't required to actually flow...they only move tiny vols of fluid. In a system that requires flow bangos don't rate in my book. Not that i really care but they look crap too

Dual lines get equalised at the rails anyway as you have described so same issue for pumps...fluids being non compressable an all, the pressure throughout the whole system is the same so doesn't matter where the T piece is. Also,, path of least resistance is to engine so again i doubt there's any issue?

John, the whole heated fuel thing is total bollocks in my experience. On cruise maybe things get a little hotter but so? Think of the mass of fuel versus the mass of air, the temp reduction at vapourisation, the heat soak in the fuel rail from engine contact etc etc....a few deg extra fuel temp is so insignificant in the scheme of things.

I'm not saying i have the best system possible but it has worked faultlessly for 4 years now supply a high compression engine pretty high boost and making big power.....if ever there was a combo that would test a fuel system it is mine and it has passed with flying colours....

anyone care to argue that?

 

[cribbj]

No argument with your system Justen; you've proven that it works.

As with most problems, there are always several different ways to solve them. I'm just presenting an alternative to the traditional way, which is to deliver 800 HP worth of fuel to the motor all the time, even if it only only wants 40 HP. To me that just doesn't make good sense.

As far as the fuel heating and evaporation issue, it's an engineering fact that as you heat up fuel, it loses density and therefore BTU's, or whatever energy unit you prefer. So the same volume of fuel will make less power. I saw this first hand when I worked at Cat.

I also saw first hand, with my own car, that when I allowed the pump to run at 13 volts all the time, I had a lot of pressure buildup in the tank from the circulation and heating. After reinstating the charcoal filter, and PWM'ing the pump down to 9v at idle, no more pressure, and no more fumes.

 

[JustenGT8]

Yup the stepped voltage option is used OEM alot. I ditched it on my other GT4 as you could pick the hesitation in fuel pressure pick up but with refinement it should work.

I agree the fuel can heat up, just that this issue in the real world makes no difference to performance.

My fuel smell issue is just from the braided lines 'breathing'....nowhere in my tank setup to see increased pressures.

All good, just trying to keep it simple for Rod so his beast can hit the road sooner

BTW it's a SARD AFPR that i use.

 

[sideshow]

if u get pressure build up on return cant u just put larger return line and better flow fuel press reg

i hardy ever run the staged fuel pump voltage in conversions

u want fuel pums to have a nice steady voltage and not flow to increase or decrease

i always run full voltage to fuel pump when i wire conversions

 

[Zuffen]

Ok, I've sorted how to eliminate Banjos at the engine end of things but how about on the output of the pump?

The pump has a F/M adaptor with a non-return valve that has a horribly small orifice (around 2mm) that is fastened to it. This adaptor is set up for a Banjo fitting. This again has a small 5.5mm orifice.

I wouldn't mind being rid of the banjo.

Did you just delete the non-return valve and attache the fuel line directly to the first fitting? I don't see a problem with this as the fuel tank is around the same hieght as the engine (if not higher!) so it won't leak back into the tank and the injectors will stop it flooding.

 

[Cobber]

Rod,

The residual fuel pressure will make the fuel ppump run backwards when shutting it down and possible damage. I used one of these check valve fittings from speedflow on my 044 pump.

http://www.furiousperformance.com.au/store/index.php?main_page=index&cPath=177_189_203

 

[Zuffen]

Cobber,

Thanks I just ordered 2 non-return valves and tails.

One day this thing will run!

 

[JustenGT8]

I just deleted the the check valve...in fact mine didn't even come with cherck valves but previous pumps did. My surge tank gravity feeds the pumps via x2 1 inch lines so always fuel in pumps.

I have a pic of the setup somewhere i'll post it up for youse all

 

[BLOWN EA]

fuel set up

hey there the fuel system i had was similler with 2 fuel pumps and a swirl pot when i got the car going then when i took it to get the rest of the work done on it the mechanic told me to get rid of it because if one pump was to stop working the car would run lean and go bang and cost me so i went and got a magnafuel pre filter 2000hp fuel pump and an after filter the feed line to the fuel pump is - 12 3/4 fuel line from there i have - 10 ali hard line up to a y block and then in to both fuel rails and then out in to a 2000hp fuel pressure reg and then return to the tank is a -10 line here are some pics of the tank and fuel pump set up when we were fitting it in to the car

 

[fredio54]

I am usually a fan of overkill, but for 600hp, a single 044 should be adequate with some headroom at the low fuel pressures a boosted 1uzfe will see to make that power. Consider for a second your 2 x 2.0 4 pot @ 300hp scenario. would you really put a 700hp pump on a 300hp engine? I wouldn't. I'd put one on at around the 400 - 500 mark, a 910 or 909 or something. I used a single 044 on my 2.0 4 pot, but I'm aiming for 500hp crank at nearly 30psi. That translates to 1000hp for the 1uz, and if you were aiming for that, I'd say you were going about it the right way. As said though, the only real problem is fuel heating, but it's still less than ideal.

I'm with cribbj on this one.

For the record, I kept the check valve and tested it to flow "heaps" of fuel at as much as 100psi (bravery ran out there) into a bucket. I couldn't see flow falling as pressure went up (flowing out semi horizontal, and parabola didn't change) , but I could hear the pump load up as I wound up the pressure. Restriction to flow is way way more important on the suction side, hence the large inlet on the 044.

I've mulled over the dual pump - one failing thing a few times. It really depends on failure modes in the pumps. If they always stop dead, then one pump is the better choice. If they gradually wear out, then 2 and one are pretty much equivalent.

Fred.

 

[fredio54]

PWM on the pump is an excellent idea indeed. Not only does it use less power and put out less heat, it allows the regulator to work in a narrower range of flow and therefore be more accurate too! Accurate stable fuel pressure = better tune and potentially more power and better economy/drivability etc.

Fred.