RB25 sidefeed injectors! - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

wowzers9930 · 04-04-2014, 07:38 AM

Okay with my goal of 500whp I decided to stick with the stock side feed rail. My fuel setup is Walbro 400 pump, Deatschwerks 740cc injectors, Nismo FPR...

Rawbrokerage recommends upgrading to top feed and going with 1000cc injectors for my goal. What do you guys think? Is 740 enough injector for pump gas 500whp?

OBEEWON · 04-04-2014, 08:41 AM

It should be but you will be running a higher duty cycle than if you did 1,000cc. I really hate to say this but higher HP RB25's are a pain in the neck to tune. Thats why I dumped mine for a 1J.

wowzers9930 · 04-04-2014, 08:51 AM

I got tuning covered, Prolly going haltech platnium pro and having Mike at Innovative Tuning tune it. I just need to know if they will be at a healthy, okay duty cycle. Id like people who have used 740s and made decent power to let me know their results.

dftsilvia · 04-04-2014, 06:44 PM

you will be at very close to maxing out 740s if your trying to make 500whp.
just do it right the first time and take the advice raw brokerage gave to you.

funny your having innovative do the tune. they are right in my hood

edit* at 80% duty cycle u will max out 740s.

cotbu · 04-04-2014, 10:44 PM

Tuners consider all injectors maxed out at 80%, not that they are or can't go to 85-90. it's like a rule of thumb.
Anyway if your tuner suggest a size, it's probably a good idea to follow it. Not all tuners, tune the same. You could have a tuner that tunes those 1000cc injectors to 80% and still not make that 500hp goal.
That being said, using a B.S.F.C. of .65....max duty 80%, 740cc's should be enough for 500hp and leave some wiggle room. I wouldn't use DW injectors for this though, preference!
So sure even a bad tuner should be able to get 500hp from an rb25 with 740cc injectors and supporting mods on pump gas, but it would be less stressful with 1000cc injectors.

*fliprayzin240sx* · 04-04-2014, 11:34 PM

Id ask the guy who's gonna be tuning your stuff...if anybody's opinion would matter the most at this point, it would be that guy. Personally, I think 740cc on an RB is enough to do 500, 850cc should be good to about 600-650.

04-04-2014, 07:38 AM	#1
wowzers9930 Leaky Injector Join Date: Nov 2012 Location: Pittsburgh PA Age: 29 Posts: 54 Trader Rating: (0) Feedback Score: 0 reviews	RB25 sidefeed injectors! Okay with my goal of 500whp I decided to stick with the stock side feed rail. My fuel setup is Walbro 400 pump, Deatschwerks 740cc injectors, Nismo FPR... Rawbrokerage recommends upgrading to top feed and going with 1000cc injectors for my goal. What do you guys think? Is 740 enough injector for pump gas 500whp?

04-04-2014, 08:41 AM	#2
OBEEWON Post Whore! Join Date: Feb 2006 Location: Hightened State of Emergency Posts: 6,051 Trader Rating: (9) Feedback Score: 9 reviews	It should be but you will be running a higher duty cycle than if you did 1,000cc. I really hate to say this but higher HP RB25's are a pain in the neck to tune. Thats why I dumped mine for a 1J. __________________

04-04-2014, 10:44 PM	#5
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 47 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	Tuners consider all injectors maxed out at 80%, not that they are or can't go to 85-90. it's like a rule of thumb. Anyway if your tuner suggest a size, it's probably a good idea to follow it. Not all tuners, tune the same. You could have a tuner that tunes those 1000cc injectors to 80% and still not make that 500hp goal. That being said, using a B.S.F.C. of .65....max duty 80%, 740cc's should be enough for 500hp and leave some wiggle room. I wouldn't use DW injectors for this though, preference! So sure even a bad tuner should be able to get 500hp from an rb25 with 740cc injectors and supporting mods on pump gas, but it would be less stressful with 1000cc injectors. __________________ LoverTechnologies "Half Broken Things!"

04-04-2014, 11:34 PM	#6
fliprayzin240sx Man w/ CTSV & a Car Seat Join Date: Aug 2002 Location: Tampa Posts: 17,998 Trader Rating: (19) Rides Gallery: fliprayzin240sx Feedback Score: 19 reviews	Id ask the guy who's gonna be tuning your stuff...if anybody's opinion would matter the most at this point, it would be that guy. Personally, I think 740cc on an RB is enough to do 500, 850cc should be good to about 600-650. __________________ If you think Zilvia has too many assholes... CLICK HERE!!!

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04-04-2014, 08:51 AM	#3
wowzers9930 Leaky Injector Join Date: Nov 2012 Location: Pittsburgh PA Age: 29 Posts: 54 Trader Rating: (0) Feedback Score: 0 reviews	I got tuning covered, Prolly going haltech platnium pro and having Mike at Innovative Tuning tune it. I just need to know if they will be at a healthy, okay duty cycle. Id like people who have used 740s and made decent power to let me know their results.

04-04-2014, 06:44 PM	#4
dftsilvia Zilvia Member Join Date: Oct 2006 Location: buffalo Posts: 248 Trader Rating: (5) Feedback Score: 5 reviews	you will be at very close to maxing out 740s if your trying to make 500whp. just do it right the first time and take the advice raw brokerage gave to you. funny your having innovative do the tune. they are right in my hood edit* at 80% duty cycle u will max out 740s.