ewuzh

iTrader: (20)

I'm trying to learn more about the fuel system. So there's two ways of increasing the amount of fuel delivered. One is to increase fuel pressure (flow velocity). The other would be to increase the injector size (volume). Following that, would this be a valid fuel system setup for supercharging?

larger injectors (ex: 370cc or 555cc)
AFPR to lower base fp
FMU for increasing fp when boosting
stock fuel pump, no additional in-line pump

The Stillen S/C kit included the in-line pump because the stocker can't provide enough flow at the higher fuel pressure needed when boosting. But if we have larger sized injectors, we don't need as high of fuel pressure because there is more fuel per injector pulse and as a result we wouldn't need an additional/supplemental fuel pump. yay or nay?

subs1000w

your right on everything except you need to replace the fuel pump no matter what, the stock pump cant provide enough volume to keep up with the bigger injectors

dont bother with an inline pump just slap a wlbro 255 intank and be done with it

slimer

iTrader: (13)

yay. PM me if you have more questions. Mike and I both have done a lot of research on this. Check the stickies for some sites with formulas.

iansw

iTrader: (7)

I've gone through 2 Walbro Fuel Pumps - both within 1 week of installing.

If it wasn't for that inline pump I would have never made it home.

I say install the inline pump but have it switched off until one day you need it.

ewuzh

iTrader: (20)

That doesn't sound good. I just got my walbro in the mail.

So the inline pump by itself can pump enough juice for running the engine, I'm guessing below 3000rpm?

SPiG

iTrader: (7)

Hard wire your walbro. I have heard that really helps its shelf life and helps it flow better since the stock puny gauge wiring can't get enough power to it.

iansw

iTrader: (7)

THe Inline pump by itself flows enough and is a high enough duty cycle that I've run without the inline pump working at all and it's been fine through my raised redline.

I30tMikeD

iTrader: (8)

I have mine hard wired.

You can by a simple kit for cheap to do it at www.DeatschWerks.com

ewuzh

iTrader: (20)

Hard wired meaning wired directly from the battery with some kind of relay in between hooked up to the ignition ON power?

I30tMikeD

iTrader: (8)

yep, that's it

Fred Allen Burge

[QUOTE=ewuzh]I'm trying to learn more about the fuel system. So there's two ways of increasing the amount of fuel delivered. One is to increase fuel pressure (flow velocity). The other would be to increase the injector size (volume). Following that, would this be a valid fuel system setup for supercharging?

larger injectors (ex: 370cc or 555cc)
AFPR to lower base fp
FMU for increasing fp when boosting
stock fuel pump, no additional in-line pump
/QUOTE]


You forgot the 3rd way of increasing fuel, increasing the injectors pulse width (making it stay open longer).

Also, what's the point of adding larger injectors if you are just going to lower the fuel pressure? Lowering the fuel pressure negates the larger CC injectors.

And, if you are going to use an FMU you will want an upgraded pump to keep up with the additional fuel pressure the FMU will create (the pump has to work a lot harder when the FMU raises the pressure to 70, 80, or more psi).

And finally, in my humble opinion if you are under 10 psi just run the FMU and upgraded fuel pump, skip the adjustable FPR and the larger injectors.

allen

I30tMikeD

iTrader: (8)

You are not going to lower base fuel pressure enough to negate larger injectors. Yes, it will cause them to flow less but it doesn't negate them. That is if your running 370's or larger. The idea of lowering base fuel pressure is for those who do not have the fuel management to control them at start up or idle. A AFPR is needed for a set up like 370's, Z32 MAF, and an FMU or SAFC

Sock injectors, an FMU, and upgraded fuel pump will work fine for lower boost levels...but pusing 8,9,10 psi is just too much for an FMU and stock injectors. A turbo VQ30 can make 350whp on 10psi. You would need to run something crazy like 130psi of fuel pressue to get enough fuel to do that. I used that set up when I was first turbo and had to run 95psi of fuel pressure to keep a decent AFR at 250whp

ewuzh

iTrader: (20)

Well I guess my question should have been:

For lower boost levels, is there a way to run only the stock fuel pump? Either with a combination of larger injectors and/or AFPR and/or ECU program.

I30tMikeD

iTrader: (8)

No, do not run the stock fuel pump. You can get a walbro new for less than $100. It is just silly not to get one.

subs1000w

maybe but i wouldnt risk it

ive never met anyone that had a bad thing to say about a walbro pump and i know alot of people running them i have a 255 in both my max and f150 and have had no problems

JdoubleOe703

iTrader: (6)

just wondering, for the 370cc injectors, which ones are they( brand, years)? I see something about 300zx and the sr20det engine ones , but still am unsure. also can i mix and match or is it preferred to all be the same( example 4 from sr20det and 2 from 300zx)? I dont know anything about injectors...

IceY2K1

iTrader: (3)

These guys are talking about 4th gen injectors...our 5th gens use different injectors.

If you're looking for a set of 380cc for your 5th gen...check my thread out: http://forums.maxima.org/showthread.php?t=444605.

JdoubleOe703

iTrader: (6)

i c... so for 5th gen's what are our options? is it only the 380cc ones?

IceY2K1

iTrader: (3)

Plug-N-Play, ie no cut-n-splice or spacers:
Power Enterprise 380cc/510cc ~$830 retail
Nismo 480cc ~$700 retail
Deatchworks rebore OEM injectors

Cut-n-Splice w/spacers:
Bosch
RC Engineering 370cc-600cc or so $550+