a healthy rule of a/f - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

mystacarlo · 03-23-2008, 10:21 AM

My current setup is a healthy rb25, gt3071r turbo, stock injectors, stock maf, walbro 255lph pump and s-afc2.

At 10lbs, my a/f is around 11.6 in full boost and drops off to about 11.2 to redline. My question is, is this ratio good or am i hurting my power at such a low boost level.

And as i go up in boost, whats a general rule i should follow when it comes to the boost and a/f ratio reading?

louisdaboois · 03-23-2008, 01:50 PM

your afr's are fine, if its a dd. if youre horsepower hungry, 12.5 under boost is what you call "best lean torque". keep in mind the leaner you get it, the chance of detonation increases. throw it on the dyno, and see what youre motor likes the best is my suggestion.

johngriff · 03-23-2008, 11:06 PM

Your AF/R is fine. 11.2-11.8 on pump, no reason to go any leaner.

If it runs good @ 10psi I would upgrade the EMS before turning the boost up, there are some evil things that can happen with the ignition map (detonation) with the safc + that 3071r.

http://www.zilvia.net/f/showthread.php?t=116999

mystacarlo · 03-24-2008, 02:22 PM

i jus see that i had i wrong, i hav a 3076r on the car, but the backhousing is rediculously small bein a .48 but thats how i got the car, i plan on goin up to a .63. I went on a run last nite with my boys, and wen we pulled over to let the car cool down, my back housing and manifold was glowing red, i can see that backhousing is choking the motor.

03-23-2008, 10:21 AM	#1
mystacarlo Leaky Injector Join Date: Mar 2008 Location: Nassau, Bahamas Posts: 77 Trader Rating: (0) Feedback Score: 0 reviews	a healthy rule of a/f My current setup is a healthy rb25, gt3071r turbo, stock injectors, stock maf, walbro 255lph pump and s-afc2. At 10lbs, my a/f is around 11.6 in full boost and drops off to about 11.2 to redline. My question is, is this ratio good or am i hurting my power at such a low boost level. And as i go up in boost, whats a general rule i should follow when it comes to the boost and a/f ratio reading?

03-23-2008, 11:06 PM	#3
johngriff Post Whore! Join Date: Jun 2004 Location: Long Beach, CA Posts: 4,103 Trader Rating: (4) Rides Gallery: johngriff Feedback Score: 4 reviews	Your AF/R is fine. 11.2-11.8 on pump, no reason to go any leaner. If it runs good @ 10psi I would upgrade the EMS before turning the boost up, there are some evil things that can happen with the ignition map (detonation) with the safc + that 3071r. http://www.zilvia.net/f/showthread.php?t=116999 __________________ [email protected]

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03-23-2008, 01:50 PM	#2
louisdaboois Zilvia Addict Join Date: Dec 2006 Location: LA, CA Age: 32 Posts: 851 Trader Rating: (28) Feedback Score: 28 reviews	your afr's are fine, if its a dd. if youre horsepower hungry, 12.5 under boost is what you call "best lean torque". keep in mind the leaner you get it, the chance of detonation increases. throw it on the dyno, and see what youre motor likes the best is my suggestion.

03-24-2008, 02:22 PM	#4
mystacarlo Leaky Injector Join Date: Mar 2008 Location: Nassau, Bahamas Posts: 77 Trader Rating: (0) Feedback Score: 0 reviews	i jus see that i had i wrong, i hav a 3076r on the car, but the backhousing is rediculously small bein a .48 but thats how i got the car, i plan on goin up to a .63. I went on a run last nite with my boys, and wen we pulled over to let the car cool down, my back housing and manifold was glowing red, i can see that backhousing is choking the motor.