This is to people running aftermarket fuel pumps and regs .What fuel pressure do you run.I am going to be running a walbro gs3442 and malpassi reg and 450cc injectors just wanting to know what pressure to set it at.Thanks in advance.

standard magnas run 40 but i run mine at 50 because of cams and additional mods, hope this helps.

i assume you have some sort of forced induction? being that you upgraded the injectors and all

you would be wanting something in the range of 40-50PSI over atmosphere. If you malspassi is 1:1 the base setting would be somewhere between 40-50psi. and wil add pound for pound as vaccum decreases (with throttle opening)

some pressure regs are 1:1.1/1.3 or more but its not much of a concern, since raising the pressure of the system squeezes just a little more out of the injectors. Personally i woudlnt go below 40, since most cars run about 38-40 from the factory.

Yeah was told by tuner to keep mine between 40-50 PSI..:)

thanks for the responses looks like 50 it is.

whats your setup CRACKAJNR?

Dont mean to pry, but are you from around brissie (some reason i thought i read it somewhere) like myself?

You want to set it lower if you want more power.

15 parts air to 1 part fuel will make more power than 10 parts air to 1 part fuel.

You need to lower the fuel pressure if you have fitted CAI, extractors and mild mods like that.

Lowering the fuel pressure is a VERY crude way of adjusting the open loop fueling from the ECU. Instead of fitting a programmable ECU and pulling fuel that way, you can lower the fuel pressure.

Also noticing you have changed injector size, were you having dramas keeping the fuel rich when on power? Not meaning to nit pick, but changing injectors without programmable fueling is pretty rough, and can lead to damage not to mention horrible fuel econemy.

Question:

Why such the upgraded fuel setup? The stock reg is good for 10psi boost, and the stock pump is apparently good for 180kw+ NA. Same deal with injectors you tend to get close to 200kw atw NA on stock injectors.

Piece of mind.

If fueling fails, it often slowly fails and causes big problems when leaning out. Fuel pumps, regulators and injectors tend not to completely fail, they start to lose operation slowly causing severe lean conditions in a motor.

I have seen many engines ruined from a faulty FPR or dodgy pressure pump, replacing them with new things doesn't cost a lot and is piece of mind definatly!

for points sake you will make more power at 15:1 then at 10:1 but you would make more at around 13.5:1 on a hi-comp NA and also give the engine a chance at keeping its ringlands

ofcourse as lean as possible when in a cruise situation, but for power you need the extra fuel to keep temps down in the cylinder enough to prevent detonation/pre-ignition (from excess heat) thus a power robbing misfire.

for points sake you will make more power at 15:1 then at 10:1 but you would make more at around 13.5:1 on a hi-comp NA and also give the engine a chance at keeping its ringlands

ofcourse as lean as possible when in a cruise situation, but for power you need the extra fuel to keep temps down in the cylinder enough to prevent detonation/pre-ignition (from excess heat) thus a power robbing misfire.

Exactly, I was just making a point.

Adding fuel pressure makes mixtures richer, a bad thing for conditions across the board.

(Y) good to see we are on the same level

I was asking the other q's about forced induction, and what not, because thats a pretty serious fuel system for a NA even with bolt ons and aftermarket ecu to manage it.

Well, you dont really need a new fuel pressure regulator if you have aftermarket ECU management do you.

Unless of course you want an extra few percent out of the injectors.

4g64 + intercooled turbo + microtech and injectors are just std 450cc 4g63 turbo items .All will be revealed in good time.

sha-whing

In that case CRACKAJNR sounds like you have built yourself a useful fuel system, cant wait to hear about it all.

Well in that case, I suggest 50psi base pressure, which when idling will be around the 39-42 mark depending on your motor/cams.

450cc even with the standard turbo will max out above around 12-14psi with standard fuel pressure. if you run higher (50)psi, you will be able to run more boost before the injectors max. You should get 16-18psi boost with 50psi fuel pressure.

What turbo, 14b? They can really push some pressure but flow doesn't really increase past 16-18psi boost so you should be pretty well right for fueling with the 450cc's if thats the case.