alternative to larger injectors

Post by **chrispy** » Mon Jan 05, 2004 2:51 am

Are there arny alternatives to getting larger injectors? I know the injectors can only stay open for a short period of time , but if you raise the pressure to the injectors it should flow more fuel through them in the same short time. Someone was telling me about a FMU , a fuel management unit, that basically does what i said above. I was ot sure if we had any other options because it seems like everyone just gets bigger injectors.

Website · Post by **quiksilvia** » Mon Jan 05, 2004 2:51 am

the safc by apexi will let u adjust the fuel curvve to maximize your power, but u will fo sho need new, larger injectors eventually.

Post by **chrispy** » Mon Jan 05, 2004 2:51 am

i have the safc , i was just was wondering if there is anything elese to use besides larger inj.

Post by **Beau** » Mon Jan 05, 2004 2:51 am

You can raise/lower the fuel pressure to trick the computer into richening/leaning out the A/F ratio. It's more of a fine tuning tool than to make injectors work when they shouldn't, though. I plan on using this method to tune my SR instead of spending a lot more money on more electronics. Keeps a bit of a sleeper look to the car.

Post by **180fan** » Mon Jan 05, 2004 2:51 am

no way around it. you want more fuel in there, you'll need to either 1. richen it up via s-afc or 2. fuel injectors.

Post by **240SXer** » Mon Jan 05, 2004 2:51 am

Beau wrote:You can raise/lower the fuel pressure to trick the computer into richening/leaning out the A/F ratio. It's more of a fine tuning tool than to make injectors work when they shouldn't, though. I plan on using this method to tune my SR instead of spending a lot more money on more electronics. Keeps a bit of a sleeper look to the car.

Is there any way to go with 550cc injectors and getting a Fuel pressure regulator and actually have it idle well and stuff? I thought Stang alone was kinda required for Larger injectors. Unless you get an ECU retune that is.

Post by **trpower7** » Mon Jan 05, 2004 2:51 am

Wow, there is again, TONS of misinformation here. Here are your various solutions to fuel problems.

1) Injectors: Injectors will only flow so much. Period. 270CC injectors can't be pushed by an increase in fuel pressure very much farther than 270CC. In general, if you stick with stock injectors, you want to use............

2) FMU: An adjustable fuel pressure regulator. By using one of these you usually put 8ish PSI of fuel pressure for every 1PSI of boost. This in effect FORCES more fuel through your injectors. This is rudimentary and not always effective. For a low boost setup, 5-7PSI, intercooled, an FMU usually works fine. If that doesn't suit your needs you will have to get..........

3) Bigger Injectors: The problem with bigger injectors is the stock computer will not drive them. Well, it will, but it will always be stupid rich because it thinks they are 270CC and will still drive them accordingly; it can't take into consideration that they are now substantially larger. If you want bigger injectors you'll need something like........

4) SAFC II: This little unit alters the MAF signal to correspond to different sized injectors, or otherwise. Since it can tune +/- 50% you can use something like 370CC injectors and have the SAFC turn down the pulse-width so you get the appropriate fuel level. This requires at least a rudimentary knowledge of tuning. The max you can go on a KA with an SAFC is 370CC injectors. 440CC maybe, but that's really really really pushing it. If this doesn't suit your needs you can get a.........

5) JWT ECU: This can drive up to 72lb injectors, or 740CC. Since it's a complete retune of the computer to your specs, you can have it run whatever you want. However, it's not tuneable. Plug, play, drive. IF you want to REALLY tune you'll have to get a..........

6) Standalone Fuel Management Unit: Haltech, MOTEC, TEC3, etc. These are fully tuneable computers in every respect and completely replace the stock computer. For hardcore users only baby, these typically run in the $2K range.

Post by **240SXer** » Mon Jan 05, 2004 2:51 am

Ya, that's why I thought with larger injectors you'd need some way for the ECU to lower the pulse rate, especially at idle. It seems like if you lowered the pressure to compensate for larger injectors it'll just make the fuel atomization worse and will have other problems because of that.

Post by **Onizuka** » Mon Jan 05, 2004 2:51 am

or, there is always the 5th injector setup. Like just putting one 550 or 720 on the plenum. I dont know how it works myself but WD runs that setup on his R32 gts.

Post by **SRdave240** » Mon Jan 05, 2004 2:51 am

Or there is this...

http://www.kingpinperformance....1#131

Website · Post by **quiksilvia** » Mon Jan 05, 2004 2:51 am

in that article he said "a reasonable Boost level of 16-18 psi" those damn sti guys hella cheat, we have sick *** cars with only 10-14 psi.

Post by **Movingviolation240** » Mon Jan 05, 2004 2:51 am

IMHO if you run an FMU you deserve to have your motor blow up in a few weeks or months. Most of the KA turbo kits out there run like 90psi of rail pressure to be safe at 7psi. At that high of a fuel pressure the injector's are allmost stalling out (they can't open or close against all that pressure). Not to mention you are pushing all the seals in the fuel system to the max.

KA-T's have a horrible reputation for safety, I think the fuel system is responsible for 90% of those problems.

If you don't want to upgrade your stock injectors you can always add 4 more and an additional injector controller. Don't make the mistake of runnind one or two injectors in front of the TB either, that dosn't work out very well either. You end up with un-even fuel distribution and a lean cylinder.... you can guess the results from there.

Basically you get what you pay for, especially in your fuel system. So if you can't afford to do it right can you afford to buy a new motor when you do it wrong?

PaulOrlando, FL

Post by **240SXer** » Mon Jan 05, 2004 2:51 am

isnt that she same problem with running a single fogger Nitrous system, the first few cyls pick up all the good stuff, the rest lean out. It does not seem like that good of a setup. Direct port fuel injection is the only way to go it seems.

I've got a walbro pump on my stock SR20det injectors, and stock FPR. Think that's an issue at all?

Post by **Movingviolation240** » Mon Jan 05, 2004 2:51 am

No your current settup is great for sub 250rwhp

Paul

Post by **strikingimage240** » Mon Jan 05, 2004 2:51 am

you can run an alcohol injection setup that will by far outdo any extra injector. We actually install the kits and they are run by haab switches that activate after a predetermined boost level. It is kind of a pain because you have to have a small fuel cell up front for the alcohol but it is cheaper than a front mount and you can boost just as much. We have plenty of fd's that use this setup.

Post by **trpower7** » Mon Jan 05, 2004 2:51 am

Alchohol isn't practical for most DDs. It's also slightly unreliable unless you get a 4-injector system that will even distribute. Same way as nitrous, you put one injector before the TB and you get uneven distribution and a blown cylinder #4. For all practicality and reason the aforementioned outline is the way to go. Not to mention the hassles of a fuel cell, wiring, activation, and getting alchohol in the first place, monitoring the levels, etc. Seems like a lot of hassle when you coudl have just gotten better fuel management in the first place.

alternative to larger injectors

alternative to larger injectors

Nissan Forums

Infiniti Forums

Datsun Forums

Technical Forums

Classifieds / Marketplace

Nissan Motorsports

General Forums