Thread: Increasing fuel pressure to 4 bar. benefits?

In the near future, I'm planning on having JWT reflash an ECU for my setup, which would include the POP charger program and cam program(S4's). While I'm at it I'm thinking about having them adjust it for a 4 bar fuel pressure setup.

So the question is, are there noticable benefits to increase fuel pressure? Adreas Miko says it provides better fuel atomization, but I want more opinions. Keep in mind I am all motor. And yes, I know I need to buy a Nismo fpr.

It could provide better fuel atomization but I don't see why you need so much fuel for a NA setup. Even if you get the Nismo FPR and get JWT to tune it your car will still be running rich and you will end up losing power. I think just by sending your injectors to get cleaned, balanced and tested will increase your fuel flow and will make your car run better without dumping all that extra fuel.

http://www.sr20forum.com/turbo/199821-fuel-pressure-4bar-always-better-than-3bar.html

Here's the summary of that thread:

Yes. 4 bar will always be better than 3 bar. Get the 4 bar program.

-G

thanks gomba.

Not true. If you get the FPR and raise the FP to 4bar, and have an ECU matched to it, you will not run rich. You will not make much more power, but you will not lose any, either.

If you send off your injectors to somewhere like RC for balancing/blueprinting/etc., they'll POSSIBLY flow more, but that's no guarantee. Say they are 259's, and RC does their thing to them and they come back to him with flow test results of 300's. Now he's got 300cc injectors, but still only has fuel pressure at 3bar, and ECU tuned for 259's. NOW he would run rich, as he's pushing more fuel and the ECU isn't compensating for the increased fuel flow from the clean injectors.

Bottom line, run a 4 bar setup with the ECU tuned. You won't lose anything, and will more than likely gain a bit, and keep the same fuel economy that you had before.

Kind of sounds like it wouldn't be worth the couple hundred dollars?

It's a free mod, since you're reflashing the ECU. Do it! With the other supporting mods, you'll actually gain free power. I didn't realize that it wasn't on a stock motor. Reading > me.

The downside you are going to need to buy an FPR if you don't already have one and you go with the 4 Bar. The plus sides are the fuel will particularize or turn into mist better (atomization) burning more of the fuel faster. Also the release of the fuel from a higher pressurized state has a cooling effect on the fuel. These both can mean better power (not much but at least in theory) and better MPG. It leaves room for upgrades too I think it is worth the cost of the FPR

can the stock fuel pump handle 259cc at 4 bar? or will a walbro be needed? i honestly think it's not worth it to buy more stuff just to run 4 bar, unless you are going to go turbo later on or something.

I believe the stock fuel pump is a 190lph fuel pump, no?

If so, then the equation for determining what cc/min can be handled with a 190LPH pump, you calculate x = 190LPH x 16.67, where x is the determined cc/min.

For your question, a 190lph pump can handle 3167.3cc/min until it reaches it's maximum flow rating. This of course would lead me to believe that you would have no fuel pressure, at this rating. The reason why I think this, is that I would assume that the 190lph pump would be at cavitation, as it's at it's peak flow rating. I could be way off, but the bottom line is that you're more than fine.

I believe 259's at 4bar would probably be in the 300~310cc/min range, so you're flowing ~74lph, which is less than half of the rating of a 190lph pump.

My calculations could be way wrong here, so I'll post up a thread in the technical information area with formulas for conversions.