Fuel Injector + FMU + Fuel Pump last minute questions...

[MarkEmark]

Hi, I will be getting a custom turbo kit that I've been waiting for for about 2.5 months FINALLY in a couple of weeks or so.

Anyway, I was only planning on using a Vortech FMU, 10:1, with a Spearco FMIC, and of course, 93 octane gas at 7 psi with a T3...But, I've been reading around here, and have heard bad things about JUST using an FMU for 7 psi, hearing that it's not enough and that it places too much stress (pressure) on the fuel system, specifically the injectors and fuel rails which will be running at a high-duty cycle with 7 psi.

My question--is a 10:1 FMU enough for 7 psi? Or, will 7 psi with the same FMU be fine with a better Walbro fuel pump, OR, would 370 cc injectors + FMU be fine, OR, 370cc injectors + FMU + fuel pump for 7 psi be fine?

I don't want to belittle the importance of the fuel system...

I've tried searching for a lot of these answers, but I can't find specific questions that address them...Will SR20DET 370cc injectors drop right into the KA fuel rail w/o modifications? If so, I've seen numerous sets of four going for about $125, seems pretty good.

Sorry if it seems like the topic has been beaten to death, but I need some real info, as I'm actually turbocharging my KA, not just post-whoreing about... :icesangel

Thanks in advance fellas.

Marc

[ExoniX]

I know the NSport kit runs an 7:1 FMU on the stock fuel system at 7 PSI so if anything get a 7:1 FMU and you should be fine i think

[MarkEmark]

Indeed, and they also use a high performance Walbro fuel pump...Basically, what would be better, the FMU and 370cc's or the FMU and the fuel pump? (keeping in mind that the fuel pump is pretty expensive...btw, anyone know hwere to get it for cheap?!?)

[S13Ka24e]

Why wonldn't you just use the fuel pump and the injectors with no fmu? I mean 370'cc (which do drop right in, but of couse you need something to control the larger injectors) are fine for 8-9psi so you do not need the fmu.

[Structure240sx]

the fmu and fuel pump will be better. with fmu and injectors you would be running way too rich especially off boost.

[MarkEmark]

Thanks for the input thus far. What would need to be reprogrammed if I dropped in 370's? Whats the cheapest place anyone's found a Walbro fuel pump (th "255" model I always hear about). Other than Walbro, what are other good (and reasonably priced ) brands to use? I know XS uses Nippon...Thanks!

[S13Ka24e]

Well i should say there is what it cheap and what is good. The FMU + fuel pump is the cheap easy way too go. If you drop in 370cc injectors you would need either a S-AFC or something like that or try the 'hacked maf'. Which if you go with injectors + fuel pump + S-AFC (btw it will not run rich you can lean/rich it your self) you start to add alot of money. If you try the 'hacked maf' (there are numorus posts on it) you only injectors + fuel pump. If you go the fmu + fuel pump i would go with a 8:1 not 10:1

[MarkEmark]

Okay, but you all think 10:1 with no fuel pump is a bad idea?Again, anyone have any good cheap sites for the walbro?

[S13Ka24e]

Well as the pressure in the fuel rail goes up the flow of the fuel will go down, so since 10:1 is a high ratio and at 7psi you would have (43.5 + 70) 113.5 psi of fuel at boost, i would say you would have to run a fuel pump. What ever you deicde good luck!

[S13Ka24e]

$109

http://www.lightningmotorsports.com/walbro.htm

[king_johnthegreat]

Ebay has the Walbro 255lph for about $84-$89 plus like $8 for shipping. Thank you guys for asking/asnwering these questions, too. I was gonna ask the same thing real soon!John

[WDRacing]

http://www.summitracing.com http://www.jegs.com for fuel parts pieces.

[MarkEmark]

Yes, I just saw that ebay was selling a bunch of brand new pumps w/installation kits/instructions for $82...unfortunately, none of them were for the S14...Damn...

[SloS13]

Im pretty sure they are universal

[king_johnthegreat]

I have seen them for the S14, you may just need to try back every once and while.John

[SloS13]

how is the s14 pump different than another pump. The pump is just 2 wires and a hose. I bet whatever 'kit' you get, you're gonna have to splice wires anyway

[:: orion ::]

It's the sock on the end of the pump that's different...

An S13 sock sits at the wrong angle and can cause starvation on hard corners (road racing)...

S14 socks sit at a weird angle, and any aftermarket pump should retain the same general setup.

Walbro does not offer a direct fit S14 kit, but one place dug around their inventory and mix-and-matched an S14 255 pump with a sock from another car to get almost an exact fit S14 kit - I'll see if I can find the link to the shop...

Later - Brian

[TomsMR2]

10:1 is huge.. too huge.

[hannibal]

A FMU just squeezes more fuel thru your stock setup. This adds a great deal of stress to the system. I think the FMU is a less reliable than adding larger injectors and you dont wanna skimp on your fuel system.I would recommend getting the injectors. The SR injectors drop in and theyre not that expensive. But you gotta control them somehow. The hacked MAF is probably the cheapest way. I'm still learning how that setup works. Then there are piggybacks, more expensive and probably easier to tune.Either way you go (FMU or injectors), you should add a bigger fuel pump.

Jay

[SHiFT]

The magic number here is 7, 7 psi. At 7 psi a FMU is a great cheap alternative to add more fuel, as stated above. You won't lose out on gas mileage when you don't need to. FMUs only pump more fuel when you are under boost, when you're just cruising in 5th or something like that you won't be wasting gas, it'll be just like stock. About the raised pressure in the fuel rail, I forget who said it but one of those famous car guys said most stock fuel rails are capable of 1000psi before becoming a problem, so reliability shouldn't be an issue. As long as you stay around 7psi you're do great with FMU + fuel pump.

[SloS13]

i have a 12:1 for sale btw. Just got it in the mail today (used) but decided to go with safc and injectors instead, so lemme know if you're interested

[:: orion ::]

About the raised pressure in the fuel rail, I forget who said it but one of those famous car guys said most stock fuel rails are capable of 1000psi before becoming a problem...

Fuel rail, maybe (I doubt it though...). Rubber fuel lines, NO! - Some say 65psi on them for a max pressure.

And a stock S13 fuel pump will in NO WAY support the pressure/flow needed here...an S14 may, but I wouldn't risk it.

DO NOT run an FMU without a bigger pump, preferably the 255 High Pressure (or similar).

Later - Brian

[MarkEmark]

Brian,I emailed you...any luck on finding that link?!?

[:: orion ::]

Here's the link to the archived thread over on Freshalloy Forums...in the Best of 240SX section.

Basically, the guys at FTF Motorsports ar woking with Walbro to get an S14 kit made...

E-mail [email protected] for more info...

Later - Brian

[SloS13]

cant you just clean and re-use your sock filter?

[Structure240sx]

orion, how did u seal ur hacked maf? is it a "gasket" of epoxy plus all the tape? i think im gonna try this out once the rest of my kit is here in a couple weeks. sorry for kinda jackin the thread but i didnt want to start a new one for one reply

[:: orion ::]

Clear epoxy called "The Welder"...

I also taped the hell out of it b/c it was initially a blow-thru setup, and leaked ridiculously...now as a draw thru (traditional setup) I have no issues with it.

Later - Brian

[TurboKA37]

i have a question about upgrading the fuel system with a NSport stage 1 kit. lets say i get the stage 1 can i eventually upgrade to 370cc injectors and a S-AFC. I assume if i do this i will no longer require the FMU from the kit. would the 370 injectors with the S-AFC be a safer set-up? and does the S-AFC provide enough adjustability to add all the fuel i need with the turbo kit? thnx

[WDRacing]

Yes

[TurboKA37]

good.