If i get a fuel pressure gauge and reg can i up the fuel pressure at all on the standard fuel pump as i have 380cc injectors , can i make them flow like 440cc injectors am running 1.05 bar on a TD05 with scooby ecu on 93 wrx have a afr , boost gauge , knocklink .Have also got a hks fuel cut raiser and a dawes device was thinking up upping boost to 1.2 bar ? As this would probably do me for modding the car .Or is 1.1 bar the absolute limit for 380cc injectors ? What is standard fuel pressure meant to be with vac line off ? and what is the max pressure of standard fuel pump ?

thanks for any views.


Mark

 

You'll need to run 4 bar fuel static fuel pressure. You will need an uprated pump to do this well as you will then be asking for 5.3 bar fuel pressure if you run 1.3 bar boost. I think the standard pump would struggle severely. You would also need to get an SX rather than FSE reg as the latter are only supposed to be used up to 5.0 bar IIRC.

You might be easier just getting 440s as once you've done the SX and pump you will be over £300 anyway.

 

If i fit larger injectors and get it re-mapped do i have to get uprated pump and reg or can i use standard.?

Mark

 

Most change the pump when going substantially over 300 BHP.

 

Hi mate do u know what power u are making? im fitting a hks fuel cut and dawes with upratrd pump in a few weeks am lookin for about another 35-40 rampant little ponies ave got a 95 wrx

 

Dr Banks - on the same sort of topic:
Is an FSE reg required for the following - MY99 LINK'd UK car, decat,induction,dawes,TD05FE, boost target approx 1.2 or 1.3 bar. Have the uprated Walbro pump but have been told by a Motec mapper that they dont really see the need for an FSE reg. Estimated power goal 300-320 bhp
Sorry for butting in KLR16V

 

LOL
The good Doctor is at it again, creeping up the power targets. KLR16V mentioned 1.2 bar max target, likely 1.1, JB points to 1.3 bar hehe


That's what we like, ambition and a good target!

 

The Uprated FPR is advisable when fitting an uprated Pump as it can easily 'over-run' the tiny Oem fitment causing instability in fuel flow/pressure making mapping awkward

Cheers

 

I'm running TD05 FE, Walbro GSS342 and a fuel pressure regulator with 380 cc injectors (MY98). In a run with 1.21 bar of boost and 3.2 bar at idle in the fuel rail the vacuum line IN. I got a 10.1 AFR...

I thought this was pretty high, so I tried by decreasing the fuel pressure to the stock 3.2 bar at idle with the vacuum line OFF, I got and average 10.5 AFR... with 1.21 bar

I could bet with the stock fuel pressure and the Walbro GSS342 fuel pump it's possible without a fuel pressure regulator get good and safe AFR (about high 10's or low 11's) for up to 1.35 bar aprox, regarding the injectors duty, because they surely are working near to 100% duty cicle.

I'll make some testing and I'll post the results.

Regards from Chile

 

Fredysan,

I have a 94 wrx with std ecu 380cc injectors, FSE pressure reg, std fuel pump, avc-r ect. only getting 12.5:1 arf at 1.1 bar boost with FSE set at 3.2 bar vacc off.

Lat time i checked my injector duty cycle it was 100%


If you are getting 10.5 afr @ 1.21 bar boost on 3.2 bar vacc off.

why am I getting 12.5 afr @ 1.1 bar boost on 3.2 bar vacc off.


I also have a fuel pressure gauge, when I reconnect the vacc line. the pressure is 2.5 bar. This will rise from 2.5 to 3.3 on full boost vacc on.

is this rise in pressure enough or is it a sign of my fuel pump struggling.

Should my injectors be at 100% on this level of boost, could there be a problem with my injectors, or MAF.

The fuel pump could explain why im not getting the AFR i want and could the MAF be misreading at the same time to give 100%% duty

I carnt understand why Im seeing 100% duty and low afr when I set the FSE to 3.2 vacc off.

Any advice?

Cheers

Mark

 

I would have thought being a 1:1 rising rate regulator you should be seeing the base pressure of 2.5bar (With pipework connected to FPR diaphragm) plus the 1.1bar boost equivalent in fuel pressure (1:1 Regulator) so 4.3bar fuel pressure on full boost. Its very likely the fuel pressure shortfall is due to the pump being unable to supply the flowrate on full boost hence the pressure drop. You are also getting close to the full capacity of the 380's without running higher base pressures
I know I was seeing 100% IDC @ 1.1-1.2bar then moved to 550cc injectors


Cheers

 

Thanks

What about my duty cycle, should it be as high as that on 1.1 bar

Thanks again

 

On 380cc injectors its likely to be around the 100% IDC mark @ 1.1bar

Cheers

 

Mark:

Really, I don't know what happen with my engine and inyectors (380 cc Impreza MY98) ... I haven't measured the duty cicle but with 15 psi and 20 psi with 38 psi of fuel pressure (With vacuum line off...) And I got AFR's of 10.7 to 10.5, the lowest value was 11.2...

It seems this is normal in MY97-MY98 engines...

 

Hi guys

i fitted a walbro fuel pump last night, Had a right faf of, I disconected the white connector and tried to run the car till it stalled but it wouldnt even start. I undid the filler cap to relieve pressure but fuel still pissed out when I removed the pipes. Any way i got the pump in but was quite concerned that I had to cut the wires to the connnector to connect the walbro wires, i cut them as close to the top connector as possible and used bullet connectors to joing the wires. Is This ok, do they need insulating tape or ssomething, bit concerned as they are surrounded in vapour at the top part of the assembly.

cheers

 

I can't see a problem using a bullet connector to join them.

I did mine last week and put some heat shrink over the joint.

If you've still got it out then why not seal it all up with insulating tape .

 

cheers, might try some heatshrink, but the pump has cured my problem. Since fitting the pump the fuel pressure was already up by 0.1 bar giving me 3.3 bar vacc off, this gave afr's of 10-11.5 on full boost of 1.1 bar, The problem is now, I think the injectors are maxing out at high revs, e.g. at 4000 rpm the afr is 10.1 but as I approch 6000 rpm the afr aproches 11.5 which is ok i think but I think Im stuck with the 10.1 at low revs. brecause I can only adjust fuel pressure to increase fueling across the board.

cheers

 

Just in case there is any confusion...

Delboy, if the fuel pressure is set at 3.2bar with vac disconnected (atmos) and 2.5bar with vacumn connected... 1.1bar of boost will not give 3.6bar of fuel pressure if correctly fuelling... fuel pressure on 1:1 reg is boost pressure on top of atmospheric so 1.1boost + 3.2 = 4.3

The reason for this is that with the vacumn connected it is under vacumn (clever eh ) at 0 vacumn it will be 3.2bar fuel press and at 1.1bar it will be 4.3bar fuel press.

Rob

p.s. i am running 380inj @4bar base pressure and getting 10.4:1 AFR at 1.6bar to the redline... oh yeah, that is also on my 2.5

 

that sounds about right, I hit 4.3 bar fuel pressure with 1.2 max boost this lunchtime with 3.2 bar vacc off (2.5 vacc on) afr 11-11.5

 

What afr's are people aiming for on bull boost ? I think the standard ECU brings it as high as high 9's low tens ? I think 11.5- 12 rich enough ?

 

Oops I didn't take into account the 0.7bar vacuum @ idle - my mistake
Funny that - the concept of vacuum @ idle

 

Horses for courses

I ran 10.4:1 for safety, however.. leaning out to 11.2:1 gave me a nice increase in power...
10.4:1 is very rich IMHO though..

On higher octane fuel i would run 12:1, (meaning with adatives rather than just SUL)

Rob

 

Cheers Rob is that from positive boost onwards or do you end up at 10.4:1 starting slightly leaner at lower boost ?

 

I did a run in fourth gear and got 10.2 from low revs up to 11.5 at top end

Is this normal, it feels a bit sluggish at bottom end now, dont think there is anything I can do unless I get a mapable ecu and 550cc injectors

by the way im using optimax with NF booster but carnt get low 12's without det, probably because I still have top mount intercooler, max induction temps of around 70 degrees. at 1.2 bar i get a bit of det, so setled for 1.15 bar. Just waiting for my FMIC to turn up.

cheers

Grant,

When I installed my hks fuel cut and added apexi avc-r with decat exhaust, upped the boost to 1.1 bar I got 315 bhp and 265 lb/ft at well lane last year. had to use octain boosters tho!. but couldnt sustain the power for long, I would start to see det after 5 mins blast. Now I have fuel pump and regulator I can increase the fuel. Once I have FMIC, should be able to run all day at least this power I hope!!

 

That could be right I know sometimes they lean out the map at higher revs to squeeze a bit more out of the turbo increasing EGT slightly to aid turbo which is running out of puff. Usually though its gets richer as the revs increase? thoughts anyone ?