Drivetrain Air Fuel Ratios
#1
07-03-2019, 07:11 AM
#2
07-03-2019, 07:38 AM
The general ratio has nothing to do with the car OR the engine..!
12.8 to 13,2 is a good rule of thumb for most ALL internal combustion engines.
On med/high boost, a little richer is needed. The harder the acceleration, the richer THAT part of the system needs to be, then taper off back to a 13+/- to 1 for steady state driving.
Cruising at a stead speed, on flat ground, a little lean is fine.
The addition of said goodies will in effect...change what your engine is getting because of the original computer mapping isn't changing automatically, the new parts normally cause the system/mapping to go leaner than desired.
It's good that you are inquiring about changing the mapping to keep your engine running it's best.
The addition of an air/fuel gauge might be a good addition to your gauge package. Here's one to look at.
https://www.summitracing.com/parts/i...SABEgK_sPD_BwE
Mike
12.8 to 13,2 is a good rule of thumb for most ALL internal combustion engines.
On med/high boost, a little richer is needed. The harder the acceleration, the richer THAT part of the system needs to be, then taper off back to a 13+/- to 1 for steady state driving.
Cruising at a stead speed, on flat ground, a little lean is fine.
The addition of said goodies will in effect...change what your engine is getting because of the original computer mapping isn't changing automatically, the new parts normally cause the system/mapping to go leaner than desired.
It's good that you are inquiring about changing the mapping to keep your engine running it's best.
The addition of an air/fuel gauge might be a good addition to your gauge package. Here's one to look at.
https://www.summitracing.com/parts/i...SABEgK_sPD_BwE
Mike
#3
07-03-2019, 12:13 PM
The stock JCW tune in my 2003 Mini S ran around 14:8-15:1 at cruise......and under WOT, it was around 11.0-11.5:1..depending on RPM.
For supercharged motors....I've always heard that a "safe" AFR is around 11-11.5:1. When you start getting up into the 12.5's...you are too lean. When you are down into the 10-10.5 range...you are too rich.
For supercharged motors....I've always heard that a "safe" AFR is around 11-11.5:1. When you start getting up into the 12.5's...you are too lean. When you are down into the 10-10.5 range...you are too rich.
#4
07-03-2019, 12:14 PM
The general ratio has nothing to do with the car OR the engine..!
12.8 to 13,2 is a good rule of thumb for most ALL internal combustion engines.
On med/high boost, a little richer is needed. The harder the acceleration, the richer THAT part of the system needs to be, then taper off back to a 13+/- to 1 for steady state driving.
Cruising at a stead speed, on flat ground, a little lean is fine.
The addition of said goodies will in effect...change what your engine is getting because of the original computer mapping isn't changing automatically, the new parts normally cause the system/mapping to go leaner than desired.
It's good that you are inquiring about changing the mapping to keep your engine running it's best.
The addition of an air/fuel gauge might be a good addition to your gauge package. Here's one to look at.
https://www.summitracing.com/parts/i...SABEgK_sPD_BwE
Mike
12.8 to 13,2 is a good rule of thumb for most ALL internal combustion engines.
On med/high boost, a little richer is needed. The harder the acceleration, the richer THAT part of the system needs to be, then taper off back to a 13+/- to 1 for steady state driving.
Cruising at a stead speed, on flat ground, a little lean is fine.
The addition of said goodies will in effect...change what your engine is getting because of the original computer mapping isn't changing automatically, the new parts normally cause the system/mapping to go leaner than desired.
It's good that you are inquiring about changing the mapping to keep your engine running it's best.
The addition of an air/fuel gauge might be a good addition to your gauge package. Here's one to look at.
https://www.summitracing.com/parts/i...SABEgK_sPD_BwE
Mike
#6
07-04-2019, 06:44 AM
The stock JCW tune in my 2003 Mini S ran around 14:8-15:1 at cruise......and under WOT, it was around 11.0-11.5:1..depending on RPM.
For supercharged motors....I've always heard that a "safe" AFR is around 11-11.5:1. When you start getting up into the 12.5's...you are too lean. When you are down into the 10-10.5 range...you are too rich.
For supercharged motors....I've always heard that a "safe" AFR is around 11-11.5:1. When you start getting up into the 12.5's...you are too lean. When you are down into the 10-10.5 range...you are too rich.
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