A/F and Timing vs Turbo Boost
Thread Starter
Joined: Nov 2001
Posts: 5,649
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From: Warr Acres, OK
A/F and Timing vs Turbo Boost Should you richen up A/F as turbo boost goes up? For instance, say you tune a 7 psi car to 11.5 A/F and now changes are made to the car so it has 12 psi. Should you continue to add more fuel as boost levels go higher? Is there a general rule as to how much more fuel to add as boost goes up? What about timing? Should timing be further reduced as boost goes up. What would be a good WOT timing and A/F to shoot for on a 12 psi car?
Teching In
Joined: Jul 2005
Posts: 41
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From: CT
For every 1 psi of boost increase, you should increase fuel by approx. 6.8%
Remember, that N/A cars work at atmospheric pressure, 14.7psi, and boosted cars work at atmospheric +.
For every 14.7psi increase in boost, or 1 atm, you need a 100% increase in fuel.
100/14.7=6.8
Now, remember, that is simply the rule, and will get you very close.
Of course, every engine tunes a little bit differently, so you need to make the proper "fit" for your car, but that formula will put you close.
Good luck.
edit- in regards to timing, I'll leave that one to you or others that know the lsx platform, I'm still learning it.
Timing is the killer, man, not enough and power suffers, too much and BOOM!!
I suggest easing into your optimum timing settings.
Remember, that N/A cars work at atmospheric pressure, 14.7psi, and boosted cars work at atmospheric +.
For every 14.7psi increase in boost, or 1 atm, you need a 100% increase in fuel.
100/14.7=6.8
Now, remember, that is simply the rule, and will get you very close.
Of course, every engine tunes a little bit differently, so you need to make the proper "fit" for your car, but that formula will put you close.
Good luck.
edit- in regards to timing, I'll leave that one to you or others that know the lsx platform, I'm still learning it.
Timing is the killer, man, not enough and power suffers, too much and BOOM!!
I suggest easing into your optimum timing settings.
you can't make infinite hp just by adjusting afr as the boost goes up at a given octane.
safe 11.5 is ok at any boost level, but for a given octane and raising boost you will want to run the timing down low (as you fight knock)
safe 11.5 is ok at any boost level, but for a given octane and raising boost you will want to run the timing down low (as you fight knock)
