I'm about to install some W41 cams into my LD9, and I'm using Brown Top Injectors and I have an adjustable FPR. So my question is what are your thoughts on increasing my fuel pressure before I start tuning for the larger cams? I've been reading around other forums and you seem to be able to gain a bit better atomization with a higher pressure, to a certain point anyway...
Has anyone here played around with this before? Do you think I have anything to gain from it? The injectors are already big for my application.
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My belief on this is that the higher pressure will make the car try to puch more fuel through the injector in the same pulse as what "stock" would be. In theory this might help atomization, but it would also richen you up a bit unless you change your injector pulse and make the injector "close" sooner.
i might be all wrong though.
Edited 1 time(s). Last edited Monday, June 20, 2011 3:25 PM
It definitely would make it run richer without changing the injector constant.
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Right, and just change the constant. There is a calculator in hpt that calculates how real injector size changes based on base fuel pressure.
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i get that upping the pressure would make it run rich but wouldnt the 02 sensor see that and in-turn back the fuel off from the electronic side of things?
Brad, the 02 sensor is only able to "pull" so much fuel - but do remember it only does so during partial throttle / low rpm / idle.
During WOT it goes to the tables directly and if the FP has been increased the computer won't compensate for the extra fuel. It'll run richer.
A re-tune is always necessary if you up the FP, be it changing the inj. constant or working the VE tables a bit.
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ah, well @!#$.. thats good to know. thanks a lot, chris.
so, its good to up the pressure over stock for better atomization and then just fine tune the fuel electronically thereafter?
From what I've read increasing helps atomization to a certain point, then it hits a point where the higher pressure stops helping and starts hurting the spray.
I was just hoping someone on here had tried it out and possible had some input.
I'll probably bump my pressure 10psi and go from there.
Paying someone to install parts and bragging about it being fast, is like watching someone bang your wife and being proud to raise their kids.
