AFR
04-04-2010, 02:08 AM
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C32AMG.335 e92 fbo.protomotive996 gt2
AFR
Hi everyone,did someone try to dyno his C32 running 185mm pulley with two different AFR ? 11.x and 13.x .wich setting is faster ??
Thanks.
Thanks.
04-04-2010, 04:09 AM
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http://www.carcraft.com/techarticles/ccrp_0402_innovate_air_fuel_ratio_meter/power.html
Air-Fuel Ratio Meter - Tune In, Turn On, And Make PowerBest
We mentioned the stoichiometric air-fuel ratio (14.7:1) that is the ideal ratio for lowest emissions, but this isn't the best ratio for power. It used to be that 12.5:1 was considered the best power ratio, but with improved combustion chambers and hotter ignition systems, the ideal now is around 12.8:1 to 13.2:1. This is roughly 13 parts of air to one part fuel. It's what combustion engineers call an excess fuel ratio and is intended to ensure that all the air is used to support the combustion process. This is because air is the oxidizer in combustion. Too many enthusiasts think that adding additional fuel beyond the ideal to create a richer mixture will make more power. This doesn't work because you can only burn the fuel when you have enough air to support combustion. That's why engines make more power when you add a supercharger or nitrous-you're shoving more air in the cylinder so that you can burn more fuel. Regardless of the amount of air in the cylinder, it still requires a given ratio of fuel to burn. Add too much extra fuel, and power will decrease.
When it comes to fuel mileage and increased fuel efficiency, this ratio changes again. All new cars run at 14.7:1 air-fuel ratio at part throttle because this is the lowest emission point. But depending upon the engine, it's possible to run an engine at leaner mixtures like 16:1 or more at part throttle to gain mileage. The difficulty with this is that driveability and throttle response suffers at these ratios. Engine response is lazy and stumbles are commonplace. Each engine will be different, but there is fuel mileage to be gained by fine-tuning your carburetor. Don't be intimidated by these lean mixtures at part throttle. You won't burn the engine up since it is making very little horsepower at part throttle cruise-often less than 30 hp.
04-04-2010, 09:14 AM
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C32AMG.335 e92 fbo.protomotive996 gt2
I'm very much a layman when it comes to AFR's, but this is an article that I found that may be a good reference:
http://www.carcraft.com/techarticles/ccrp_0402_innovate_air_fuel_ratio_meter/power.html
Air-Fuel Ratio Meter - Tune In, Turn On, And Make PowerBest
We mentioned the stoichiometric air-fuel ratio (14.7:1) that is the ideal ratio for lowest emissions, but this isn't the best ratio for power. It used to be that 12.5:1 was considered the best power ratio, but with improved combustion chambers and hotter ignition systems, the ideal now is around 12.8:1 to 13.2:1. This is roughly 13 parts of air to one part fuel. It's what combustion engineers call an excess fuel ratio and is intended to ensure that all the air is used to support the combustion process. This is because air is the oxidizer in combustion. Too many enthusiasts think that adding additional fuel beyond the ideal to create a richer mixture will make more power. This doesn't work because you can only burn the fuel when you have enough air to support combustion. That's why engines make more power when you add a supercharger or nitrous-you're shoving more air in the cylinder so that you can burn more fuel. Regardless of the amount of air in the cylinder, it still requires a given ratio of fuel to burn. Add too much extra fuel, and power will decrease.
When it comes to fuel mileage and increased fuel efficiency, this ratio changes again. All new cars run at 14.7:1 air-fuel ratio at part throttle because this is the lowest emission point. But depending upon the engine, it's possible to run an engine at leaner mixtures like 16:1 or more at part throttle to gain mileage. The difficulty with this is that driveability and throttle response suffers at these ratios. Engine response is lazy and stumbles are commonplace. Each engine will be different, but there is fuel mileage to be gained by fine-tuning your carburetor. Don't be intimidated by these lean mixtures at part throttle. You won't burn the engine up since it is making very little horsepower at part throttle cruise-often less than 30 hp.
http://www.carcraft.com/techarticles/ccrp_0402_innovate_air_fuel_ratio_meter/power.html
Air-Fuel Ratio Meter - Tune In, Turn On, And Make PowerBest
We mentioned the stoichiometric air-fuel ratio (14.7:1) that is the ideal ratio for lowest emissions, but this isn't the best ratio for power. It used to be that 12.5:1 was considered the best power ratio, but with improved combustion chambers and hotter ignition systems, the ideal now is around 12.8:1 to 13.2:1. This is roughly 13 parts of air to one part fuel. It's what combustion engineers call an excess fuel ratio and is intended to ensure that all the air is used to support the combustion process. This is because air is the oxidizer in combustion. Too many enthusiasts think that adding additional fuel beyond the ideal to create a richer mixture will make more power. This doesn't work because you can only burn the fuel when you have enough air to support combustion. That's why engines make more power when you add a supercharger or nitrous-you're shoving more air in the cylinder so that you can burn more fuel. Regardless of the amount of air in the cylinder, it still requires a given ratio of fuel to burn. Add too much extra fuel, and power will decrease.
When it comes to fuel mileage and increased fuel efficiency, this ratio changes again. All new cars run at 14.7:1 air-fuel ratio at part throttle because this is the lowest emission point. But depending upon the engine, it's possible to run an engine at leaner mixtures like 16:1 or more at part throttle to gain mileage. The difficulty with this is that driveability and throttle response suffers at these ratios. Engine response is lazy and stumbles are commonplace. Each engine will be different, but there is fuel mileage to be gained by fine-tuning your carburetor. Don't be intimidated by these lean mixtures at part throttle. You won't burn the engine up since it is making very little horsepower at part throttle cruise-often less than 30 hp.
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04-06-2010, 02:44 PM
#10
12.5 is a good afr, just make sure you're not getting any detonation. and also, AFR can be tossed out the window if you're injecting meth. never do any tuning with meth! (use race gas instead) when you're done tuning, replace the race gas with meth. When you run meth the AFR will be wrong since gas burns at 14.7:1 and meth is 6.5:1. even your lamda sensor will not read down to 6.5:1 and that would still be too lean for a meth engine. When you mix meth and gas all readings are off.
04-06-2010, 03:39 PM
#11
Ali, i think everyone here running 185 pulley has an AFR lean from 13.5 and up, this issue is still and no one has solve it till now on a C32, the car has now 8 years old and we are selling the car and the secret will die with it, maybe if you can solve it yourself!!!! waiting you.
04-06-2010, 08:38 PM
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2003 porsche 996 turbo
Ali, i think everyone here running 185 pulley has an AFR lean from 13.5 and up, this issue is still and no one has solve it till now on a C32, the car has now 8 years old and we are selling the car and the secret will die with it, maybe if you can solve it yourself!!!! waiting you.
