i know this has been talked about and i searched, but i just want to make sure its right for this set up. i have a wlbro intank, and i want to run about 6-7 psi of boost. i dont really want to use super high pressure with the stock injectors, so what would be best to use for this set up? its my daily driver so i want to also make sure it idles ok. i am also using only the sfmu. thanks

i just installed hrc's 255 injectors and i couldn't be happier with the way the car is running. i run around 10 psi and with those injectors it really came to life.

Accel 415 cc/min injectors, a 2.72" disk in the S-FMU, and an S-AFC will be perfect for you. This will work fine up until around 12-16 psi of boost depending on your setup.

A wideband is also a must for any car that is is siginificantly modified (like car that has a turbo on it that didn't have one from the factory) Otherwise, you're guessing at what the actual air/fuel ratio is.

if i only wanted to run a sfmu with this setup for now, would i still want these large injectors?

Yes. You will want these larger injectors so the Walbro in-tank won't be stressed by having to pump at very high pressures required for a turbo application with stock injectors.

At the very least, I'd suggest that you get a wideband. If you know how to use it, it's about a $250 insurance policy that helps prevent a $1500+ rebuild.

yea money is very tight at the moment. last question(most likly) if i got these what kind of idle pressure would i be seeing? and also would it be ok to run it with just an A/F gauge until i could get a wideband?

Originally posted by import1996rs
would it be ok to run it with just an A/F gauge until i could get a wideband?

A blinky A/F guage is completely worthless in terms of tuning...ESPECIALLY if you're running larger injectors. No one is saying you're going to blow up if you don't install a wideband RIGHT THIS INSTANT...rather we're telling you to tune with a wideband.

ok, this is what i figured, and i lied, another question. where is the best/ cheapest place to get these?

edit: will these go right on or is there anything i need to do. cant you only go like 310's on the stock ECU?

If you want your car to be well tuned, you should buy a wideband and an S-AFC to go along with big injectors and a S-FMU. To put it bluntly, you'd be dumb not to.

But, you can get away with not having either. I got away with no AFC and no wideband for about a year with no problems (then I went with the 8 injector setup) but I watched the EGT's and what my narrowband said (which gives a pretty good ballpark, but you can't actually do any real tuning with the stock oxygen sensor)

My air/fuel ratio wasn't very well tuned, but it didn't blow the engine up either. Just be CAREFUL if you decide to do this. You have to really listen to how the engine is running. If you have stock cams, pay good attention around 3000-4000 RPM's because this is where detonation is most likely to happen. It kind of sounds like popcorn or someone shaking an empty can of spray paint with that little mixer ball bouncing around. The thought of that sound sends chills down my spine.

Oh yeah... With 415's and a S-FMU you probably won't be able to pass emissions (I wasn't able to) unless you get an AFC. Otherwise, the idle pressure of 20 psi makes the injector spray patterns look like taking a leak after sex. No atmoization at all.

i'm gonna be running 450cc's with the walbro intank, on just my stage 1, however, i'm looking for a vortec sfmu as we speak! i dont know how to use a wideband though :-(

doesnt mean you cant learn.

Originally posted by Chamuko
doesnt mean you cant learn.

oh, most definitely, right now, i am in a whole new learning process about the fuel system and how to operate it. its amazing just how much people here know about all this

Originally posted by 96rs-t
i'm gonna be running 450cc's with the walbro intank, on just my stage 1, however, i'm looking for a vortec sfmu as we speak! i dont know how to use a wideband though :-(

Here's the quick and dirty method of tuning with a wideband:

1. Buy a wideband sensor and a controller
2. Install it
3. Drive around and see what your AFR is at different RPM's
4. Tune your S-AFC until you get between 11.5:1 and 12.0:1 at all RPM's and boost levels
4a. Or, raise/lower your S-FMU fuel pressure until you get the desired AFR
4b. Or, mess with the injector scalar in the 034EFI code until you get the desired AFR
4c. Or, get a Megasquirt and hook the wideband up to it and run a target AFR (closed loop at all times)

Originally posted by ner947

Originally posted by 96rs-t i'm gonna be running 450cc's with the walbro intank, on just my stage 1, however, i'm looking for a vortec sfmu as we speak! i dont know how to use a wideband though :-(

Here's the quick and dirty method of tuning with a wideband: 1. Buy a wideband sensor and a controller 2. Install it 3. Drive around and see what your AFR is at different RPM's 4. Tune your S-AFC until you get between 11.5:1 and 12.0:1 at all RPM's and boost levels 4a. Or, raise/lower your S-FMU fuel pressure until you get the desired AFR 4b. Or, mess with the injector scalar in the 034EFI code until you get the desired AFR 4c. Or, get a Megasquirt and hook the wideband up to it and run a target AFR (closed loop at all times)

just curious, how much is a wideband and a controller?

Originally posted by 96rs-t

Originally posted by ner947

Originally posted by 96rs-t i'm gonna be running 450cc's with the walbro intank, on just my stage 1, however, i'm looking for a vortec sfmu as we speak! i dont know how to use a wideband though :-(

Here's the quick and dirty method of tuning with a wideband: 1. Buy a wideband sensor and a controller 2. Install it 3. Drive around and see what your AFR is at different RPM's 4. Tune your S-AFC until you get between 11.5:1 and 12.0:1 at all RPM's and boost levels 4a. Or, raise/lower your S-FMU fuel pressure until you get the desired AFR 4b. Or, mess with the injector scalar in the 034EFI code until you get the desired AFR 4c. Or, get a Megasquirt and hook the wideband up to it and run a target AFR (closed loop at all times)

just curious, how much is a wideband and a controller?

This is the best cheap one i've found. I use it on my 350z.

Originally posted by etx

Originally posted by 96rs-t

Originally posted by ner947

Originally posted by 96rs-t i'm gonna be running 450cc's with the walbro intank, on just my stage 1, however, i'm looking for a vortec sfmu as we speak! i dont know how to use a wideband though :-(

Here's the quick and dirty method of tuning with a wideband: 1. Buy a wideband sensor and a controller 2. Install it 3. Drive around and see what your AFR is at different RPM's 4. Tune your S-AFC until you get between 11.5:1 and 12.0:1 at all RPM's and boost levels 4a. Or, raise/lower your S-FMU fuel pressure until you get the desired AFR 4b. Or, mess with the injector scalar in the 034EFI code until you get the desired AFR 4c. Or, get a Megasquirt and hook the wideband up to it and run a target AFR (closed loop at all times)

just curious, how much is a wideband and a controller?

This is the best cheap one i've found. I use it on my 350z.

were you suppose to post a link??
:shrug

i guess i should also mention that im building an 8 injector set up and was only planning on runing 255's as my primary's and 415's as my secondary. but if your not planning on running more than stage I or II, i was happy with the improvement the 255's gave. you shouldnt need an afc with that small of an injector, i'm not currently using one. but if your wanting to go past stage II and only want to buy injectors once, 415's sound about right.

so what are the biggest injectors i can run (and still pass emissions) to lower my fuel pressure with no safc or wide band. this is pretty much temporary until my funds build back up.

will the accel 30lbs/hr injectors from summit just drop into our car?