AIR / FUEL ratio...issue..

[rs200]

Install Winlog and make a log of your car's boost, RPM, AFR.
Then post here

yes I will .
but first I have to find laptop which have good batery.. 3 laptops I have at home and non of them can't hold more than 15min without batery...

[prj]

thanks.. now I understand..

Install Winlog and make a log of your car's boost, RPM, AFR.
Then post here

[rs200]

thanks.. now I understand..

[prj]

Lambda is AFR divided by Stoichometric AFR.
Because stoichometric AFR is different for different types of fuels, it makes more sense to actually note lambda.

For example the Stoichometric AFR for gasoline is around 14.7. For E85 it is around 9.8.

[willg54]

Lambda is Actual AFR / Stoichiometric AFR

[rs200]

one stupid question .. I'm NEW in that..

what is 0.89, 0.90, 1.05 lambda? 14.7 is 1.00 lambda , and under it or upper is AFR in % ? or ?
thanks..

[willg54]

Exactly. This is how it is referred to most of the time when tuning...
Really, just replace your definitions of "rich" and "lean" with "too rich" and "too lean" and you'll arrive at the same point.
"Ideal" AFR does not really exist though... too many variables, but that's nitpicking.

Cheers

[prj]

so basically you're saying you refer to lean and rich around the 'ideal' AFR of the rpm/boost/throttle site?

Exactly. This is how it is referred to most of the time when tuning...
Really, just replace your definitions of "rich" and "lean" with "too rich" and "too lean" and you'll arrive at the same point.
"Ideal" AFR does not really exist though... too many variables, but that's nitpicking.

[willg54]

By your logic an engine always runs rich.
In the current context "rich" is meant as "too rich" and "lean" is meant as "too lean".
Maybe that makes sense to you.

Example:
Running 10 AFR under 1 bar boost would be referred to as running rich, running 14 under the same condition would be referred to as running lean.

Our formula student defo runs lean on a lean map >14.7. we use lambda more so tend to map for 1.05 lambda for lean. all varies through the rpm and throttle % to get the BMEP we want. rest of the time we're at 0.88-0.9

so basically you're saying you refer to lean and rich around the 'ideal' AFR of the rpm/boost/throttle site?

sorry for hi-jacking the thread

[prj]

please educate us...how is it used when mapping an engine?

By your logic an engine always runs rich.
In the current context "rich" is meant as "too rich" and "lean" is meant as "too lean".
Maybe that makes sense to you.

Example:
Running 10 AFR under 1 bar boost would be referred to as running rich, running 14 under the same condition would be referred to as running lean.

[willg54]

Yeah, that's how a narrowband sensor sees it, not how it is used when describing mapping an engine though.

please educate us...how is it used when mapping an engine?

[prj]

was just stating how to define lean and rich! realise at WOT 14.7 would destroy it!

Yeah, that's how a narrowband sensor sees it, not how it is used when describing mapping an engine though.

[willg54]

was just stating how to define lean and rich! realise at WOT 14.7 would destroy it!

[Rocco]

with WOT we need 11 to 12.3 (more or less) with normal 98 ron fuel..as a base

14.7AFR with WOT will destroy the car

[prj]

14.7 would be stoichiometric. under that would be rich, over that would be lean.