Fuel system question

[Stpleb]

I'm upgrading my turbos, so I want to upgrade my fuel system too that way I don't have to worry about a shortage of fuel. I was wondering if I was to go with a bigger fuel pump and injectors than what I actually new to give me room for future up grades, would it kill my gas mileage? From my understanding as long as I have a fuel pressure regulator and have it adjusted properly it shouldn't. I just want to make sure I'm correct and don't over kill my fuel setup and completely destroy my fuel economy since this is still my daily driver. Thanks in advance.

[Skym]

Depends on how rich you run engine. That varies from tuner to tuner, parts installed on engine.

Normally you'll see an increase in fuel economy (running engine leaner) if not running too high of a boost level.

[caliber676]

Upgrading turbos and fuel economy don't mix

[Bruizer]

If you want a reliable and economic gtr, leave it as is and only replace what is worn or broken with oem parts. Don't look for a daily drivable car with big power cause it'll either not last long or cost big bucks

Enjoy as is.

[Stpleb]

I say daily driver but I'm only home one week a month and most of the time we take the wife's car everywhere since it's a 4 dr and we have two kids. As of right now I have forged pistons, race rods and bearings, crankshaft collar, intake, a cat back exhaust and blitz ecu. I got a steal on a set of R34 N1 turbos. I'm about to switch to Nistune ecu (I like being able to use all my stock sensors), z32 MAF's, atleast 700cc injectors, a fpr, and I'm undecided. I found walbro 255 at a decent price but for a little more I can get a walbro 400. My goal is around 500hp. I've heard of some r34 N1 setups making this. Will the 255 fuel pump be enough if not is the 400 to big? I'm going to try and get as much hp as I reasonably can out of these turbos. If I'm not close enough to my goal them I might upgrade to bigger turbos down the road.

[Stpleb]

It's really more of my toy. Lol

[Skym]

My goal is around 500hp. I've heard of some r34 N1 setups making this.

Around 455hp at engine is common with mild boost level, ECU tune, boost up mods.

Nurburgring Falken 24hour N1 R34GTR racecar produced around 500hp at engine with N1 turbo's -

https://www.youtube.com/watch?v=xkoZ5sOnQTg

Up to 550hp would require cams (Tomei Poncams or similar), camgears, ECU tune to suit.

Will the 255 fuel pump be enough if not is the 400 to big? I'm going to try and get as much hp as I reasonably can out of these turbos. If I'm not close enough to my goal them I might upgrade to bigger turbos down the road.

Injector sizing calculator -

http://www.deatschwerks.com/resources/fuel-calculators/fuel-injector-calculator

Fuel pump size calculator -

http://www.deatschwerks.com/resources/fuel-calculators/fuel-pump-calculator

[Stpleb]

Thanks for the help. Those calculators or pretty handy.

[bobbo]

I'm making 427 whp (=~500 at the crank), get 27 mpg hwy cruising at 120, 550cc injectors, N1 turbos and stock internals. Not one other piece of my fuel system has been touched. BTW if you decide to upgrade your fuel pump. DO NOT buy a Walbro.
You can rewire your fuel pump for a better power supply. There is a write up around here somewhere but it's not crucial.
I'm a huge advocate for the KISS method of doing things.

[RixR32]

What boost level are you running for that power bobbo?
That's pretty much my exact setup, and power goal (500 crank)....was wondering if 550's were going to be big enough. (I do have Tomei fuel pump though).


Rick

** Edit - Deat's calculator showed almost exactly 550cc's for 500 crank HP at 80% duty cycle. No boost level is shown though.....I would think that makes a big difference?

[Skym]

Thanks for the help. Those calculators or pretty handy.

You're welcome. Still best to get it checked by a tuner via using formula's, as that's a rough guide and some online calculators can be wrong.

There is a write up around here somewhere but it's not crucial.

Fuel pump hardwire kit (should have wiring instructions) -

http://www.deatschwerks.com/products/accessories/fuel-pump-hardwire-installation-kit-detail

Voltage to fuelpump at factory is around 10-12 volts, sometimes 10 volts at higher rpm when light's, aircon, etc is on.

Most fuelpumps lph is rated at 13.5 volts, so 10-12 volts is not enough, especially with bigger injectors. Hardwiring gives it the 13.5+ volts.

Problem with hardwiring is it heats the fuel up (fuelpump moves more fuel to and from a hot engine bay), so a fuel cooler is a good idea (as installed on N1 GTR at factory that has the fuelpump hardwired) if using car on racetrack.

** Edit - Deat's calculator showed almost exactly 550cc's for 500 crank HP at 80% duty cycle. No boost level is shown though.....I would think that makes a big difference?

From what I understand, duty cycle = how much injector is open. More boost = more fuel required = more duty cycle.

General rule of thumb is 80% duty cycle max for reliability on racetrack, but factory run it as high as 90%+ (street use).

[bobbo]

I'm at about 16.5 psi. Timing is a critical variable to consider too. That's running Shell 91 octane.