Drivetrain Air Fuel Ratios
Thread Starter
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4th Gear
Joined: Jan 2007
Posts: 315
Likes: 1
From: UK - North West
Air Fuel Ratios
Hi guys,
Could anyone tell me what AFR Air Fuel Ratio to aim for on a 2005 R53 Cooper S?
Modified with the usual stuff, cam, pulley etc.
What typical AFR values at specific RPMs should I be aiming for?
Thanks!
Could anyone tell me what AFR Air Fuel Ratio to aim for on a 2005 R53 Cooper S?
Modified with the usual stuff, cam, pulley etc.
What typical AFR values at specific RPMs should I be aiming for?
Thanks!
5th Gear
Joined: Mar 2018
Posts: 795
Likes: 122
From: SoCal
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
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.
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
Thread Starter
|
4th Gear
Joined: Jan 2007
Posts: 315
Likes: 1
From: UK - North West
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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