Bats-Wrx

iTrader: (1)

Right Spec of engine

EJ257
Arrow Rods
CP Pistons
Stock STI V3 Heads
GT30R Turbo
3" Exhaust


What size injectors do you recommend?

Also fuel System what fuel pump set-up should i use?

jonny gav

iTrader: (1)

740cc injectors and a walbro 255l/h fuel pump with an SX or fuelab regulator.

RB5 Boyo

Yep, I have 740's on my 2.0 litre RB5 with 18g turbo, walbro pump, fmic, haltec Ecu etc etc

Bats-Wrx

iTrader: (1)

I have a Walbro and Aeromtive reg.

Will the Walbro be up to the job? the car will be on the track as well.

RB5 Boyo

Yep, i have aeromotive and walbro 255, running 340bhp plus so u should be grand. plenty of people running 400+ with this kit too

jonny gav

iTrader: (1)

if you are wanting to be on the safe side go for a bosch 044 fuel pump, they are quite noisy and need custom wiring as they are too heavy duty for the standard wiring but will handle your need no problem.

bighead

iTrader: (1)

i have 850s in my 2.5 running 49% cycle ....future proof

harvey

iTrader: (48)

Exactly as Jonny says.
I have a secondhand Bosch pump if you are interested.

Bats-Wrx

iTrader: (1)

Harvey,

What ywould be the best way to run the 044?

Keep the walbro to fill a swirl pot then the plumb the 044 to the swirl pot?

Any other ides looking to keep it simple.

dazdavies

iTrader: (22)

I was running 740cc injectors on a 2.5 with a rotated GT30R.
SX Reg and a single intank walbro. 1.6bar saw arounf 80% duty peak.

Next guise of this engine will see a walbro to feed a swirt pot with a Bosch 044 feeding the rails.

Turbo will also be seeing 2bar. IDC permitting

harvey

iTrader: (48)

Bats : I don't believe in complicating things so I would simply replace the Walbro with the Bosch and retain it in the tank.
On my STi 6 I ran quite happily with this same Bosch pump on the OE wiring and that car had variously 525 to 585 bhp depending on which fuel and rolling road. The car ran 740cc injectors and they were pushed at the top end but would probably have got to 600 bhp if that was possible. The car also ran standard fuel rails.

I now run the same pump but the wiring has been uprated with a relay but this was all done while I was chasing a fuel pressure issue which turned out to be faulty readings from the guage.

I would simply run this pump and consider uprating the wiring as a precaution.

dazdavies

iTrader: (22)

Harvey you're not considering surge issues if the car is taken on the track.
Whilst an in-tank bosch will certainly supply enough fuel for 500bhp and beyond it doesn't resolve the issue of fuel vacating the area of the pickup on long right handers if the tank isn't above half full.

Considering the investment in an engine capable of 500bhp I'm sure the extra couple of hundred quid on a swirl pot and external pump would be worth spending.

harvey

iTrader: (48)

It is far easier and cheaper to make modifications to the pump carrier and pick up so the fuel pump will pick up from a very low level, far below where it was when the car left the factory. The car is fitted with a 60 litre tank and I regularly put in between 56 and 59 litres of fuel on normal road driving and on an odd occasion over 60 litres. On track I ensure the car is refuelled at quarter tank and never run in to misfire issues.

dazdavies

iTrader: (22)

Personally I wouldn't take the gamble. Swirl pot and external pump is the only guaranteed surge free way to do it.

As said a couple of hundred quid could potentially save an engine build costing thousands.

Incedently I think all of the time attackers are running swirl pots.

Cheers

Daz

harvey

iTrader: (48)

Is Bats building a Time Attack car?
Road going cars and even occassional track day cars are a long, long way from Time Attack cars.
More than one pump leads to an additional item that can fail and a lot of extra work. The swirl pot and additional pump may take up load space reducing the practicality of a predominently road going car with occassional track use.
For road going use with occassional track day, a lot can be done to eliminate fuel surge issues for very little expense as outlined above. I cannot see the logic in a race car solution,signifigant expense and effort and reduction in practicallity for probably 99% of Scooby owners where their Scooby is their primary daily transport, even if the car does see occassional track use.
Of course, if building a replica race car and engineering an expensive solution to an easily eliminated problem is what floats your boat and you have the funds and inclination, fine.

dynamix

iTrader: (3)

Swirl pot was one of the best mods on my car.

incidentally 2.5 running 840's at 83% IDC at 3.4bar static on the HTA Green at flat 1.8 bar

dynamix

iTrader: (3)

oh, and this is my daily driver Harvey. Swirl pot mounted within the engine bay with Bosch 044 underneath at the rear bulkhead, therefore no petrol fumes within the car and no lost space in the boot.

If I was doing it again, I wouldn't solid mount the 044 pump though

dazdavies

iTrader: (22)

There you go again Harvey

I personally I don't give a toss what you or the OP do fuel wise I'm just reflecting my own experiences here. You've said yourself that your car needs to remain a 1/4 tank full for your solution to be reliable.

My 500bhp road car with pickup adjustments still had fuel surge issues on the road not just track. The fuel pot solution has cost me around £250 all in (including the pump) . i'd rather that than thousands replacing my engine.

Incedently the one i'm building is going to be my one and only car. A fully trimmed four seat car. As for this takes up valuable space statement its nonsense. The swirl pot is tucked away nicely at the back of my boot leaving plenty of room for luggage and shopping etc

STiFreak

iTrader: (4)

What sort of modifications are you referring to Harvey? This might be a better option for me, as even in relatively standard form and running a Walboro 255 the STi has fuel surge issues and I am sure these are going to get worse as the power increases. At the moment I usually run my tank between half full and full.

Bats-Wrx

iTrader: (1)

Are these injectors any use Ebay item number 140249026971.

Will these fit on the phase 1.5 manifold or will adaptor kit be required?

dazdavies

iTrader: (22)

They are a phase 2 injectors. They are the exact same injectors that I have.
I also beleive an adaptor kit will be required.

Carl Davey does them and his stuff is top notch.
They can be had for £30 delivered here Carl Davey, specialist Subaru Impreza parts supply

SSCJAY

I'm with 740's aswell

Swirl pot is one of my favourite upgrades (apart from the 2.5 & gt30r), nearly had some evo in my boot once as the car got surge and completely cut out off of a r/bout.

I'm using an external Walbro and the whole lot come in well under £200.

harvey

iTrader: (48)

What a strange attitude. If you want to run a swirl pot that is fine as I already said. Your choice but for the majority of people on here it is an unnecessary expense and complication so they can make their own mind up.
Only for track use is fuelling at quarter tank advisable and that is a common sense precaution possibly not necessary. On road use the car can be run to almost empty.

The fuel pump sits on a pressed steel carrier frame and on the bottom of the fuel pump is a pick up sack. This also applies to the Walbro. The pump sits in to a tray above the floor of the tank and it is from here fuel is picked up and excess fuel returned. On corners, particularly right handers when the fuel moves to the passenger side of the car, it is possible for the pump to pick up a mixture of air and fuel or no fuel at all. Similarly on hard accelleration the fuel moves to the back of the tank and the same thing can occur.
The first improvement that can be made is to angle the carrier down so that it is closer to or touching the fuel pan. I found it was actually best to have the fuel sack horizontal and resting on the base of the pan. However, this is only a partial improvement but does make a noticable difference because on the OE car the fuel pick up sack is actuall set quite high. Similarly with the replacement Walbro.
The next modification was to completely remove the fuel sack and add a pick up made from a braised pipe fitting and a short length of fuel hose. This is assembled so that the pick up is from the rear passenger side corner of the pan and the pick up pipe lies flat on the bottom of the pan. In this way you can judge your fuel down to a very fine amount and never experience fuel surge issues on normal road work.
When I first did this mod five years ago I fitted an in line fuel filter but subsequently discovered that was not necessary and I have carried out this very inexpensive mod on numerous cars now.

dazdavies

iTrader: (22)

Not meaning to get on your case Harvey but doesn't that now give you issues with hard left hand bends now?

harvey

iTrader: (48)

No Daz, the fuel tray is slightly offset and I have had no surge issues on the road or on track with this mod. Replenishing the tank at quarter full on track seems sensible to me but on the road I am regularly adding upwards of 55 litres at a time. My last fuel was 58.09 litres and the one before that, 59.42 litres, still with no surge, fast cross country road driving. I think this mod makes 6-8 litres more usable fuel and certainly not less than that.

dazdavies

iTrader: (22)

Food for thought then for others considering this.
sorry for the crossed wires

harvey

iTrader: (48)

Cheers Daz. The only point I am making is there is a lot the average owner can do to improve an inherent issue common to all the Subarus I have driven and it costs change out of £20 and half a day of your time including the bits.
Not the belt and braces solution Matt Clark would run on Time Attack where high sustained cornering Gs are possible but perfectly OK for the majority of owners.