Injectors + Rail To Use?

[adamsrotor]

hey guys, im currently building my 25/26 and am using a greddy manifold and would like to convert from sidefeed to topfeed. im aiming for around the 500rwhp and will be using a hks rail, i noticed there is a 10.5mm (std) and a 11mm (oversize). is there really much diff and which brands make what size injectors? also there is the injector sizing issue, i was thinking around 700/750cc? i guess this would be enough to cope and wouldnt have to go to 1000cc's? what brands are good stuff? every1 tells me diff stories, i hear the 4 hole nismos are really good, then i know sard make good gear but ive heard dont use sard injectors any help on this would be apprectiated. am using a bosch 044 with surge tank and turbosmart fpr 800reg. thanks.

[JimX]

I am using the Sard 700cc injectors with 2x2530 turbos and they get up to around 80% duty cycle at full throttle and 20 psi boost. I haven't dyno'd the car yet (only road tune) but it'd be well under 500rwhp. I would think that you'd need to go larger for 500rwhp, but I am also running standard AFM's which max out, and I think once that happens the ECU will start dumping in more fuel than it needs just to be safe. So maybe my 80% duty cycle is more than it should be. Also I'm running the standard fuel reg, you can squeeze more fuel out of them with your turbosmart reg but I don't know if it'd be enough.

Speak to your tuner who would have a better idea about sizes and brands and how much extra flow your reg will get you. I have an adjustable Nismo reg but haven't installed it because I don't need it yet. I really like these Sards though, they're smoother than I expected and idle very nicely even when cold (when the ECU is behaving, it stumbles 2-3 times when aircon kicks in but it did that on the factory injectors too, need to re-program the PowerFC's idle soon). I couldn't tell these aren't factory injectors, and bigger injectors are meant to be a bit rough at idle/cruising.

I'm not familiar with the HKS rail, I'm using the factory rail (RB26) for these injectors if that helps at all.

[GTRsean]

700cc sards and stock fuel rail too. It's all in the tune.

Fuel pump setup will be a decider too in how much HP.

I was running 470RWHP at 17psi with 2530's and a sard 280L pump.

Injectors still had room left for more (500+).

Edited September 7, 2008 by GTRsean

[axe s]

Im running 800 and plenty of room to move... 450RWHP only let down but the wastegate spring not being strong enough...

Edited September 7, 2008 by axe s

[adamsrotor]

ok cheers for that guys, some very helpfull info there. looks like ill get some sards as the price is pretty good on them

[axe s]

Slide are pretty good for injectors...

[adamsrotor]

yeah slide is great for everything lol

also does anyone know how much of a difference there is between using a 11mm rail and a std 10.5mm rail? cheers

[WHITER33GTS-T]

Just go big straight up then when you want more power, as you will, then you have the fuel system ready.

I have 1000cc injectors, twin entry fuel rail, 2 x 044 pumps and a GTR pump filling the surge tank. This fuel system was on my old RB25 that made 399rwkw. It still has plenty for my new setup 25/30

[adamsrotor]

hey rob, yeah i was thinkin that but i dont wanna go too big to the point the injectors lose an efficient spray pattern. i was thinkin 800's but yeah could go 1000s. hmmm decisions decisions...

[adamsrotor]

any1 else have any input? im just about to purchase the 800's but keep thinkin should i go to the 1000's to be safe lol also is there really much difference between the single and twin spray injectors? thanks again.

[R31Nismoid]

370rwkw = 800cc no problem at all.

550's are good enough for 330rwkw to give you an idea

[adamsrotor]

cheers mate, ill stick with the 800's. what about the twin spray? worth the extra $100?

[Owgasm]

Sorry to hijack.

Are aftermarket fuel rails illegal?

Will cops say anything if they open the bonnet and see the rail and braided fuel lines?

Cheers