The air/fuel ratio of the stock SS/SC
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Joined: 04-07-06
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From: Passaic, New Jersey
Originally Posted by EndZz
Those of you who are saying you are at 14.7 and asking if it's bad take a look at this.
BTW try to keep the stock A/F ratios when modifying things and change MAP tables if you are using HPT
9.0:1 BLACK SMOKE (NO POWER)
11.5:1 RICH BEST TORQUE @ WOT
12.2:1 SAFE BEST POWER @ WOT
13.3:1 LEAN BEST TORQUE @ WOT
14.6:1 STOCHIMETRIC AFR ( CHEMICALLY CORRECT )
15.5:1 LEAN CRUISE
16.5:1 BEST FUEL ECONOMY (EXCEPT FOR HONDA MOTOR COMPANY)
18.0:1 CARBURETED LEAN LIMIT (EXCEPT FOR HONDA MOTOR COMPANY)
22.0:1 EFI LEAN LIMIT
BTW try to keep the stock A/F ratios when modifying things and change MAP tables if you are using HPT
9.0:1 BLACK SMOKE (NO POWER)
11.5:1 RICH BEST TORQUE @ WOT
12.2:1 SAFE BEST POWER @ WOT
13.3:1 LEAN BEST TORQUE @ WOT
14.6:1 STOCHIMETRIC AFR ( CHEMICALLY CORRECT )
15.5:1 LEAN CRUISE
16.5:1 BEST FUEL ECONOMY (EXCEPT FOR HONDA MOTOR COMPANY)
18.0:1 CARBURETED LEAN LIMIT (EXCEPT FOR HONDA MOTOR COMPANY)
22.0:1 EFI LEAN LIMIT
New Member
Joined: 08-29-05
Posts: 113
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From: So. Cal 605X10fwy
Actually that ratio is supposed to be about 14.7.
It means 14.7lbs of air will mix with 1lb. of fuel and combust or react and have no extra fuel/air, basically the entire "mixture" of fuel and air will react without any being wasted. This reaction isn't always perfect though, sometimes not all the air is used and it gets wasted out of the exhaust. Air is used to make power (some might argue that) but if you put more fuel in the mixture you have a better chance of burning more of the air which gets used to make more power.
So you asked is it good to run at that A/F ratio? Well it depends on what you are doing, to cruise YES you save money using less fuel, Plus it's better for the environement, un-burned fuel vapors are extremely hazordous to the environment. so you want to burn it all.
But if you want to make power then 14.7 is BAD you generally want something under 13.2 to make power, cause going fast is GOOD!!!!
It means 14.7lbs of air will mix with 1lb. of fuel and combust or react and have no extra fuel/air, basically the entire "mixture" of fuel and air will react without any being wasted. This reaction isn't always perfect though, sometimes not all the air is used and it gets wasted out of the exhaust. Air is used to make power (some might argue that) but if you put more fuel in the mixture you have a better chance of burning more of the air which gets used to make more power.
So you asked is it good to run at that A/F ratio? Well it depends on what you are doing, to cruise YES you save money using less fuel, Plus it's better for the environement, un-burned fuel vapors are extremely hazordous to the environment. so you want to burn it all.
But if you want to make power then 14.7 is BAD you generally want something under 13.2 to make power, cause going fast is GOOD!!!!
New Member
Joined: 02-26-06
Posts: 107
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From: SoCal
I need to know something.
Stock 2.2 what is the Air Fuel Ratio and the Combustion Ratio. Also how much gas is injected?
10 parts air to 1 part gas? 10:1
CR:
0.55 liters for max on one cylinder
What is it at its minimum?
Very important, experiment with gas and combustion using same dimensions, thanks.
Sorry if in wrong forum, this is probably the 2.0 tech but the damn search...
Stock 2.2 what is the Air Fuel Ratio and the Combustion Ratio. Also how much gas is injected?
10 parts air to 1 part gas? 10:1
CR:
0.55 liters for max on one cylinder
What is it at its minimum?
Very important, experiment with gas and combustion using same dimensions, thanks.
Sorry if in wrong forum, this is probably the 2.0 tech but the damn search...
Member
Joined: 06-09-06
Posts: 387
Likes: 0
From: Lyons
9:1 = Desiel overfueling. Cause everyone knows you can't go fast without leaving a layer of soot on the trakc behind you. 
Yea 14.6:1 is the best ratio for cruising cause it causes the lowest emissions. Run leaner adn you cause more Carbon Monoxide. RIcher and its' CO2 ( I think, or is it the other way around.) Either way 12:1 is ideal for a Forced induction motor. 13:1 is the temp safe limit. Get it at 12-11.8 :1 and your good.
Yea 14.6:1 is the best ratio for cruising cause it causes the lowest emissions. Run leaner adn you cause more Carbon Monoxide. RIcher and its' CO2 ( I think, or is it the other way around.) Either way 12:1 is ideal for a Forced induction motor. 13:1 is the temp safe limit. Get it at 12-11.8 :1 and your good.
Member
Joined: 03-10-06
Posts: 262
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From: central nj
Originally Posted by memphisr24
Why are you guys with 3 inch pulleys, cai's, and exhausts getting 12.5-12.8's when I'm getting 13.5-13.7 WOT!?!?!? I have the same mods.
BTW by adding a little fuel where you guys see 13.5 and it starts to go down [2600-4000rpm] you can make the power hit sooner .
Senior Member
Joined: 07-24-05
Posts: 1,321
Likes: 0
From: GTA, Ontario
I just got my AEM UEGO installed today - GMPP Stage refalsh and 42# injectors with a 2.7" pulley and the lowest AFR I got at WOT at 7K redline was 12.5. Maybe we can shut up the "it's not safe to run a 2.7" pulley with GM Stage kits" crticis once and for all
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