I have been doing a lot of research lately on tuning aids and have a few questions. I Know the difference between Lambda and AFR but i have never had any experience with lambda so i am kinda nervous.


First of all would a would the lambda value for maximum power with gasoline be the same as it would with methanol or any fuel for that matter(assuming that everything else is equal and correct)? Lets say you had the car tuned on a dyno and found that the highest peak torque value was made at a lambda of .87 on gasoline. Would it be safe to assume that if you changed the fuel to methanol that you should also shoot for a lambda of .87?

Second, is there a chart somewhere that gives you lambda VS AFR for a given fuel. I am so use to looking at AFRs it would be nice to compare for reference only.


Third, why is it that the most commonly used measurement is AFR? Is there some advantage that i am not seeing? Lambda seems more foolproof especially if you change from one fuel to another or if your not 100% sure that the fuel you are putting in your tank has no alcohol added.

And lastly, what would be a good lambda value to START with for Ethanol and or Methanol?

I am going to try and use lambda in the future so i need to get use to it now .

 

Well i answered at least one of my questions.

Alcohol Lambda Gas

6.4 1 14.7
6.2 0.96875 14.240625
6 0.9375 13.78125
5.8 0.90625 13.321875
5.6 0.875 12.8625
5.5 0.859375 12.6328125
5.4 0.84375 12.403125
5.2 0.8125 11.94375
5 0.78125 11.484375
4.8 0.75 11.025
4.6 0.71875 10.565625
4.5 0.703125 10.3359375
4.4 0.6875 10.10625
4.2 0.65625 9.646875
4 0.625 9.1875
3.8 0.59375 8.728125
3.6 0.5625 8.26875
3.5 0.546875 8.0390625
3.4 0.53125 7.809375
3.2 0.5 7.35

 

Im no expert on this at all but my meth motor seems to like 28 degrees i found out the hard way retarded turned the exhaust into a blow tourch! And the egt's were in the 500 hundreds. Im sure cris knows a good starting point.

 

Sorry busted, i took all that info out because it didnt have much to do with the original question. I will have to start a separate thread for that conversation .

 

Which was?

 

if your measuring with an 02 sensors than it doesn't matter if you read it in lambda or 02.

the wideband only reads lambda, it translate it into AFR. So if you use a wideband on alcohol, and the output is set to AFR you could be running stoic at say 6-1 but the wideband will display 14.7-1.

Reverse the case and run on gas with the wideband set to display afr for alcohol and it will show 6-1 at stoic when your gas motor is actually running an AFR of 14.7-1.

The 02 sensor itself doesn't know and doesn't care what kind of fuel the car is using, the only reason a WB02 sensor is programmed with a specific fuel is to adjust the display for the operator.

In other words use what you are comfortable with and what you know well.

 

The secret is knowing what actual AFR and ignition timing works for safe power on methanol. Also running with or without an intercooler is another factor!

 

So reading Lambda instead of AFR doesn't give you any more accurate results since there are no "conversions" taking place and you are only displaying the info the sensor is putting out? Are the problems with some wideband controllers ( AEM, Innovate) that their conversions are flawed? Would reading in lambda remove these errors?


Ignition timing for methanol.

In the process of searching for some info on lambda i ran across a thread that had a lot of interesting info. From timing with Methanol to how to read a spark plug. http://www.eng-tips.com/viewthread.c...=174777&page=1

I was planning to tune like you had suggested (start rich and lean till the engine clears out) with a conservative timing curve (Gaby's C16 map) but after reading that i don't know about the timing.





I agree, that would be a very good piece if information to have. Just in case you wanted to know i plan on running without an intorcooler.









Thanks for the info everyone!

 

First, the circuitry in even the cheapest wideband is capable of multiplying 14.7 (or whatever) by the lambda reading and displaying it to you accurately. If there is an issue with accuracy for a particular brand or model then its not related to this simple math.

Second if your reading it off the haltech datalog then you having the sensor convert its reading from digital to the analog 0-5v then the haltech is converting that voltage into lambda and so on.