Always like to share success with the forum.
(UK Turbo 97 Wagon, Currently with Scorpion downpipe and 2.5" decat system)
I'd had long discussions with various tuners in Plymouth about what order of priority I should do mods in. A common top 3 item was to replace the standard in tank fuel pump with an uprated aftermarket one. The theory is that the standard pump (125ltr/hr?) is matched to standard output and with very little in reserve. To the extent that at full throttle and high revs, you can use more fuel than the pump can deliver; so presure starts to decrease (allbeit only a few psi). This makes the mixture progressively lean, cylinder temperatures increase, pistons start to melt the crown, then hole....out cheque book!
I was convinced and purchased the recommended Pp (Walbro/Sytek ITP 160 (ltr/hr)), (Proven products had a special on Impreza kits at £95).
It sat in the garage for 2 months as I prepared myself up to what I thought would be an epic job.....whish I'd done it sooner as it was dead easy.
I did go to the precaution of tee'ing a fuel presure guage in before the injection filter, just to record the before and after.
(Before) When hot, injector rail presure was 34psi at idle and a steady 56psi at full throtle and boost (14psi).
(After) when hot, injector rail presure 38psi and a steady 61psi at full throtle and boost.
Idle is smoother, the gentle surging during acceleration is gone, full throtle acceleration is much stronger, throtle response is like a trigger.
The difference this makes to the way the car goes is
I doubt the whole job took more than 90 minutes, the access panel is inside the car just forward of the rear axle (OS), pipes and wiring is fiddly but straightforward.
I cannot beleive such a simply cheap upgrade can make such a difference.
Regards
Pete

 

glad to here it mate as i have to fit a walbro 255 ltr fuel pump to mine asap

 

Mine's with Alan Jeffrey as we speak, same upgrade. Carl
Sorensson (sole trader, formerly Proven employee) was raving about the Walbro earlier this week. Green Army

 

Pete,

Thanks for taking the time to post. I'm interested in this in preparation for my next upgrade.

I have only just posted a question about this configuration. Perhaps you know the answer to this increasing fuel pressure question?

-Steve.

 

Steve
Now this is all a personal theory that only works if the Walbro pump does not have an internal relief or regulate presure internally in any way. So with that assumption, I would argue that as the the fuel presure regulator (diaphragm presure controller) only senses inlet manifold presure, it a matter of boost presure on one side of a diagphragm and fuel presure on the other. If the base line fuel presure from the pump is higher (allbeit slightly) than that of the standard pump, then the point of equilibrium between the two sides of the diaphragm will alter. Consequently the fuel presure is proportionally higher throughout the range; in my case between 4 and 6 psi. The car ran 14.236 quarters at Santa Pod last time out, I'm convinced it's now in the 13s just by changing the pump.
Regards
Pete

 

Hi
It was Sorrensen that put me onto the pump in the first place, and I have been down Allen Jeffreys about 3 times in the last week asking endless questions about this and many other mods (he must be getting sick of me by now!).
While your down there take a look at the Scooby engine they have just built for a customer, it's a thing of beauty. Spec power is 400+ , could be running in the car shortly.
Regards
Pete

 

Pete,

Only just spotted your reply. I was monitoring my thread!
Anyway thanks for your reply. What you say makes a great deal of sense and I can see that I was being a chimp with my original question. The information I was lacking was that the fuel pressure regulator senses manifold pressure and adjusts accordingly.

So, the pump is my next planned mod however I assume one has to carefully pick one that only increases pressure 'slightly' over standard. You went for the Walbro/Sytek ITP 160 (ltr/hr). The one I see on Proven Products and the other on Flat4Online don't actually say what flow rate they are. I've got a standard (ish) MY03 WRX, anyone know what flow rate the standard pump is? Perhaps it's the same as Pete's 125ltr/hr. If so I assume the pump on Flat4Online (a Walbro 255 - is that 255ltr/hr?) would be well too much!

Any advise here greatly received.
-Steve.