Best AF Ratio
Thread Starter
Drifting
Joined: Apr 2020
Posts: 1,615
Likes: 576
Best AF Ratio
So on a mildly boosted LS3 what is the best air fuel ratio?
AI claims:
The BAP activates at 1/2 throttle or 3/4+ throttle?
AI claims:
- The recommended air-fuel ratios for a supercharged LS3 Corvette are as follows:
- 11.5:1 to 12.5:1 under full load conditions for efficient operation.
- 12.8:1 to 13.2:1 for maximum power on the dyno.
- 12.5:1 to 12.6:1 for safer performance on the street.
The BAP activates at 1/2 throttle or 3/4+ throttle?
Thread Starter
Drifting
Joined: Apr 2020
Posts: 1,615
Likes: 576
Safety Car
Joined: May 2016
Posts: 4,578
Likes: 1,786
From: Erlanger, Kentucky
Should be able to apply pressure to it but most Hobb switches activate with 3 or 4 psi which is not much. So you need a fitting that you can screw the Hobb switch into and attach to an air compressor. Turn the regulator down to 5 or 10 PSI. Attach some leads from a Volt Meter and monitor conductivity. I would think when it activates, it will be obvious on the meter.
As for AI, ignore everything it regurgitates out as all it is doing is skimming and repeating bad and completely wrong information.
I think on my Eforce GS, my AFR under power is about 11.8.
As for AI, ignore everything it regurgitates out as all it is doing is skimming and repeating bad and completely wrong information.
I think on my Eforce GS, my AFR under power is about 11.8.
Pro
Joined: Oct 2024
Posts: 660
Likes: 364
From: WI
So on a mildly boosted LS3 what is the best air fuel ratio?
AI claims:
The BAP activates at 1/2 throttle or 3/4+ throttle?
AI claims:
- The recommended air-fuel ratios for a supercharged LS3 Corvette are as follows:
- 11.5:1 to 12.5:1 under full load conditions for efficient operation.
- 12.8:1 to 13.2:1 for maximum power on the dyno.
- 12.5:1 to 12.6:1 for safer performance on the street.
The BAP activates at 1/2 throttle or 3/4+ throttle?
BAP activates at a certain boost level, completely independent of throttle position. If you have an A&A kit it turns on at about 4 psi and their instructions also provide the following instructions to test it:
Test the operation by connecting a handheld pressure pump, such as a Mighty Vac, to the pressure switch. Jump the factory fuel pump relay so the pump is running and pump pressure to the switch. You should hear the pump speed up considerably when the switch is activated.
Le Mans Master
Joined: Dec 2007
Posts: 8,353
Likes: 88
From: Somewhere in the Mid 9's TX
So on a mildly boosted LS3 what is the best air fuel ratio?
AI claims:
The BAP activates at 1/2 throttle or 3/4+ throttle?
AI claims:
- The recommended air-fuel ratios for a supercharged LS3 Corvette are as follows:
- 11.5:1 to 12.5:1 under full load conditions for efficient operation.
- 12.8:1 to 13.2:1 for maximum power on the dyno.
- 12.5:1 to 12.6:1 for safer performance on the street.
The BAP activates at 1/2 throttle or 3/4+ throttle?
Deplug yourself from AI and actually know what your car is doing. Everyone is so dumb these days. Take a night after work, or a few weeks as we did 20 years ago and know what is actually taking place with your blower, stock or aftermarket cam and valves, etc. It’s not that hard.
Thread Starter
Drifting
Joined: Apr 2020
Posts: 1,615
Likes: 576
The car is running good but I just wanted to go over things so I'll probably take it down to Cordes Performance and have them put it on a dyno to make sure the Boost A Pump and everything is operating as it should and have them go over the tune...
Le Mans Master
Joined: Jun 2015
Posts: 6,289
Likes: 1,091
From: Austin Tx
That's a good decision. They will get you sorted out.
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Thread Starter
Drifting
Joined: Apr 2020
Posts: 1,615
Likes: 576
I did a 20-80MPH pull and the wide band O2 sensor showed 11.30-11.96 during the pull. I didn't want to get too crazy, just wanted to see the AFR. I would assume the BAP activated with those #s. I'll still do the dyno tune but just wanted to see for now what it was doing.
Pro
Joined: Feb 2003
Posts: 745
Likes: 136
From: Detroit MI
Like others said, BE CARFEFUL believing AI advice. It is not vetted and just repeats whatever it sees.
Second, start getting used to Lambda instead of "AFR". Pump gas is NOT 14.7, and cheap widebands often correct back to this scale to give people a number they're used to seeing. It's still wrong and often confusing. Targeting an actual balance around 0.77-0.80 lambda is a better start.
For boosted setups, you *can* run leaner, but I usually set clients up significantly richer (with more timing) to get more knock resistance and safety margin for the occasional tank of bad gas. Remember that combustion is not necessarily a perfect process, so I like to leave some safety margin there on stock bottom end engines. It quickly becomes a game of risk tolerance for the tuner.
Second, start getting used to Lambda instead of "AFR". Pump gas is NOT 14.7, and cheap widebands often correct back to this scale to give people a number they're used to seeing. It's still wrong and often confusing. Targeting an actual balance around 0.77-0.80 lambda is a better start.
For boosted setups, you *can* run leaner, but I usually set clients up significantly richer (with more timing) to get more knock resistance and safety margin for the occasional tank of bad gas. Remember that combustion is not necessarily a perfect process, so I like to leave some safety margin there on stock bottom end engines. It quickly becomes a game of risk tolerance for the tuner.