Rb25det Injector? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

*MELLO*SOS* · 11-10-2006, 09:07 AM

Injector sizing: on 6cyl Gas motor 1cc ~= 1bhp @ 100% duty.

So at 80% duty cycle here are some rough #s...

444 @ 80% <= 350 crank hp <= 300whp @ 15% loss
550 @ 80% <= 440 crank hp <= 375whp @ 15% loss
720 @ 80% <= 560 crank hp <= 490whp @ 15% loss

So right away you can see the 444s are probably going to be too small for what you're try to do. You should get some 550s at least if not something larger (600s or 700s) so you have some room to grow. I don't know what kind of injectors the 2jz has but unless they're side feed and the right impedance you're going to have to splice in some resistors and/or a new rail in order to use them. deatschwerks.com sells drop-in rb25 injectors all day long (look on Ebay and FS area too). If you're gonna spend all that money on the Mani & HKS-2535 why not spend a little more to ensure you get correctly sized, brand new injectors? You may want to consider converting to a top feed rail, as you'll probably have better injector selection but that's up to you.

And for the leaning out problem, if you have a decent ECU to control your bigger injectors (like a PowerFC) I hear you can adjust #5 and #6 to be ever-so-slightly more rich than the others to compensate. What ECU are you planning to run? If you're just doing a ROM tune or SAFC, you could have the injectors flow tested and put the two biggest flowing injectors in the back.

11-10-2006, 09:07 AM	#2
MELLOSOS* LAID OUT Join Date: Mar 2004 Location: LAS VEGAS Age: 43 Posts: 2,015 Trader Rating: (1) Rides Gallery: MELLO*SOS Feedback Score: 1 reviews	Injector sizing: on 6cyl Gas motor 1cc ~= 1bhp @ 100% duty. So at 80% duty cycle here are some rough #s... 444 @ 80% <= 350 crank hp <= 300whp @ 15% loss 550 @ 80% <= 440 crank hp <= 375whp @ 15% loss 720 @ 80% <= 560 crank hp <= 490whp @ 15% loss So right away you can see the 444s are probably going to be too small for what you're try to do. You should get some 550s at least if not something larger (600s or 700s) so you have some room to grow. I don't know what kind of injectors the 2jz has but unless they're side feed and the right impedance you're going to have to splice in some resistors and/or a new rail in order to use them. deatschwerks.com sells drop-in rb25 injectors all day long (look on Ebay and FS area too). If you're gonna spend all that money on the Mani & HKS-2535 why not spend a little more to ensure you get correctly sized, brand new injectors? You may want to consider converting to a top feed rail, as you'll probably have better injector selection but that's up to you. And for the leaning out problem, if you have a decent ECU to control your bigger injectors (like a PowerFC) I hear you can adjust #5 and #6 to be ever-so-slightly more rich than the others to compensate. What ECU are you planning to run? If you're just doing a ROM tune or SAFC, you could have the injectors flow tested and put the two biggest flowing injectors in the back.