I don't, but I'd like to know what tuners would trust 1 intank 255 walbro (return system included) to sustain 550-ish WHP. I'm talking really trust reliably with minimal attention.

Thanks

 

I'm not a "tuner" but I do. As long as it maintains consistent fuel pressure, why not???

 

I know Alberto is runnig 650 injectors and pushing 550 plus. I am sure 550 injectors will be fine.

 

No problem at all....done many many times by many tuners.

 

go with extra big injectors so that you can run a lower base fuwel pressure.

running a lower fuel pressure allows the walbro to be able to pump more fuel...*fuel pumps flow rates decrease as pressure increases.*

 

quadcam hit it on the head. just get a set of 1000cc and FCON and your concerns are solved! lower pressure means higher pump flow capacity and more HP.

 

Just to clear things up, I never said 550cc injectors. I said 550 WHP. We're using 750cc injectors. I can see how you could make that mistake though.

 

The walbro 255 GSS 342 is only rated to about 500 crank HP by walbro. I've worked with walbro pumps for years. I like them, but I don't love 'em. I've had several failures lately (not under load, actually right out of the box). They get hot after extended use.

The pressure with walbros always falls off a few psi at idle after running for a while. I've witnessed this on Nissans/Hondas/Toyotas with single and twin pump set ups. I've always like the denso pumps, but you can't easily fit them into the Z/G housing.

 

Woo! My bad speed reading again, but it looks like you got your answer.

 

With "extra large" injectors, regardless of fuel pressure, the idle will always suffer. You can only run a large injector (ex. 1000cc) at a certain low duty without it stumbling. Active A/F feedback can help, but only so much.

 

I agree, the FCON is an amazing box, but not in everyone's budget. And let's not forget...it's not user friendly and end user tuning/tweaking is not available.

 

Thanks for the input everyone.

So far, it seems everyone who posted about the single 255 in tank, trusts it. I guess I've just been soured by the 3 recent failures I've experienced...it sucks to get an entire fuel system built, turn the key and you see 0 fuel pressure. After the third failure, I now pre-test all of the walbros I use or sell. It was crazy. All the pumps turned on internally, the pump gears didn't spin.

We're using UTEC for EMS with no plans on changing out to another platform. We plan on the CJ single pump return system, just waiting on availability.

 

Not with 1000cc low impedence injectors (HKS or RC Low Impedence), driven by an FCON, Haltech, or other EMS that can fire low impedence injectors. The cars start and idle like stock at 14.7:1'ish. You are correct, in regards to high impedence injectors.

If 550whp is your goal, a 650cc injector will more than meet your needs, with an RFS, and a walbro.

 

Correction: 750cc, 40psi base fp, 580whp on a DJ with a fresh motor

 

Damn how did you get your fuel pressure to go that low? I can only go to 52ish.

 

Drill out the yellow plastic swirl jet a little bit more. 1/8 inch maximum.

 

I currently have 640rwhp in Hi boost with one walboro, and yes its something that I dont like cuz the injectors are maxing out. what I do is allways having at least 3 gallons of VP race gas in my tank tobe on the safe side and running onlow boost wich is 540rwhp. you should pm carlitos who is a friend of mine and member of this site so that he can tell you about his current solution to this problem he has 740rwhp with nos. and yes we both use RC750 injectors and UTEC.

wellcome to our neverending quest to find a solution to fuel without an FCON.

 

Yea...I've gotten so use to using saturated injectors. I just think of them as the street standard. Big peak and hold through a resistor box (ala AEM supra) still a ***** to "hand dial" for that magic stoich idle. I want to play with an FCON! Damn you PRO DEALERS !

550 wheelish is the low boost goal. but we all know how long that lasts

Thanks Sharif

 

Interesting...

 

The new Haltech 350Z PnP unit (completely different from the current one) is a promising development. User/shop tunable and about a $2500 price point with wideband. It has sequential injection control (no batch fire like AEM), and drives low impedence injectors too (unlike AEM), controls DBW, and cam phasing too.