Fuel Pressure Reg HELP!

[PorterzSupra]

I have read stock setting is 35-40 PSI. I just put in an aftermarket adjustable one. I have all the mods plus 550 injectors, what should I set my pressure to run at for best performance? Also, when you check are you suppose to have the vacume line connected or disconnected? Having the line connected you get lower pressure then if its pluged in. So what PSI should I run it at and when I check it do I unplug vacume line?

 

[YoNkErS87t]

Your suppose to set it with vac hose off. I would set it to about 35psi.

 

[PorterzSupra]

umm... I thought STOCK was 35-40? I thought the point was to be able to turn it up a little not set it at the lowest stock pressure possible?

 

[turbomk3]

i have mine at 35 psi too

 

[theDon]

I think stock is 23-30 with, 33-40 without vac.

 

[diy guy]

for best performance go to the dyno and play around with different settings. average price here for 3 runs is $100 on a reg day, $50 on dyno day.

I think the lex/550s setup actually runs a bit richer than stock with is way rich already so if anyhing i would lower the pressure. breathing mods wont change that as the extra air is being metered, therefore compensated for.

 

[shaeff]

my fuel/air mods:

lex afm, 550's, afpr, walbro, new lines.

my BASE fuel pressure (vacuum line detached and plugged so that the AFPR can get it's reading from the atmosphere as zero vacuum) i have my pressure set at like 28psi, and i still run rich.

every car will vary, though. (my lex screw is backed all the way out, too) dont use someone else's settings.

-shaeff

 

[YoNkErS87t]

i'm with shaeff- don't use someone else's settings.

And yes the lexus/ 550 mod does run richer than stock because at idle the injectors are pretty much just dumping gas because the computer is still using the stock injector pulse. Pretty much when upgrading injectors you don't get the full affect of the injectors until you tune them to their own pulse.

We have rising fuel pressure regulaters. Meaning when boost kicks in the fuel pressure rises depending on the pounds of boost. So you could set the fuel pressure at a lower setting just to clean up idle a little. A a/f gauge or wideband would help adjusting the fuel pressure.

I would think it would be a waste of money to pay for a dyno and tune with just a Afpr. Unless your just curious to see your HP/Tq.
But thats me:wiggle:

 

[diy guy]

We have rising fuel pressure regulaters. Meaning when boost kicks in the fuel pressure rises depending on the pounds of boost. So you could set the fuel pressure at a lower setting just to clean up idle a little. A a/f gauge or wideband would help adjusting the fuel pressure.

actually most, if not all efi motors have a 1:1 fpr. it really doesnt add more fuel. what it does is balance out the pressure difference in the manifold/fuel line. during boost there's pressure pushing up into the injector so fp is bumped to counteract this, during vacumm, its the opposite, fuel is being pulled from the injector.