Air/Fuel ratio calculation

[TheBac]

Taking two of the few useful posts from the TS thread:

As much as I LOVE coal!, Nathans right! Its sinking our own ship.

You know, the more and more we see fast and faster trucks coming of age, the more prevalent were seein the big numbers put down with low smoke output! A light haze seems to be the sweet spot! I remember reading a statment from Banks a while ago about ideal diesel air/fuel ratio. Diesels start to produce visible smoke @ 18:1 A/F ratio but optimum A/F is 16:1...............There ya go, light haze

Well said Nathan. I totally agree with this from a Drag racing stand point and a street stand point. I think that a low to not smoke rule for drag racing is a good thing and can be done. For pulling I am not sure it can be done. With pulling classes setup the way they are. Basicly by turbo size I see no way around it. I know what Gale Banks say about being smoke being wasted power but I call BS. To get rid of the smoke you need and AFR of over 20. That does not make the power that and AFR of 16 does. Yes it smokes but it makes more power. A lot more power. I dont have a problem with my truck smoking the way it does. But it is not a street truck. My street truck is cleaner running than it was stock. FWIW turbo gasser smoke to. My old GN would puff black on WOT shifts with an AFR of low 11s. Most max effort turbo gassers a least haze.

I had always wondered what ideal A/F for a diesel was.
Questions:
1) How does a person log/track A/F on a diesel?
2)What sensor values would you want to look at to calculate A/F?
3) Is there a PID in EFILive for it? If not, can one be added?

 

[03 D-max]

Do wide band O2 Sensors work for diesels?

as for your Q's i dont think there is anything on the lb7's to check AFR because there isnt an O2 sensor in the exhaust. not sure if the other motors have one.

If wide band O2's will work for diesels then that is what you will need

 

[JOHNBOY]

If you wanted to use EFILive than this should work. http://www.greenlightmotorsports.co...ufacturer_id=0&option=com_virtuemart&Itemid=1

I use this hand held. I do this becuase we use use it to tune my uncles drag car.
http://www.greenlightmotorsports.co...ufacturer_id=0&option=com_virtuemart&Itemid=1

Just found this one
http://www.fuelairspark.com/Products/details/meter/diesel.asp

 

[JoshH]

I have heard of people that have put wide band O2 sensors on their truck.

 

[TheBac]

So a gasser A/F meter will work on a diesel? Interesting.

If you installed an O2 sensor in the exhaust, couldnt you use the info from that, the MAF and mm3 of fuel to figure it out?

 

[JOHNBOY]

You got it.

That would work as long as your not maxing out the flow of the MAF.

 

[03 D-max]

So a gasser A/F meter will work on a diesel? Interesting.

If you installed an O2 sensor in the exhaust, couldnt you use the info from that, the MAF and mm3 of fuel to figure it out?

i am maxing out my maf so im sure you are too

 

[TheBac]

I thought we could rescale the MAF to get higher readings? I couldve sworn I read that somewhere.



(BTW, can someone please help me stop my brain from thinking up all this other stuff while my current projects sit in the shop unfinished?) :rofl:

 

[JOHNBOY]

(BTW, can someone please help me stop my brain from thinking up all this other stuff while my current projects sit in the shop unfinished?) :rofl:

Your hopelessly lost like the rest of us.
This place is a support group for addicts like us.:happy2:

 

[malibu795]

4" pipe on a stock turbo and i very easily max the stock MAF @ 66.1 lb/min

BTW what is the range of a wide band O2?

 

[JOHNBOY]

Innovate is 7.5 to 22:1 IIRC.

Edit to add link with good info.
http://www.innovatemotorsports.com/products/lm2.php

 

[sweetdiesel]

So a gasser A/F meter will work on a diesel? Interesting.

If you installed an O2 sensor in the exhaust, couldnt you use the info from that, the MAF and mm3 of fuel to figure it out?

You should be able to use a calc PID with the sensor from greenlight

Ive read before that its not the greatest to use mm3 values instead try using Act boost/rpm

Fingers would be the good to talk to about this and IIRC he has allready made some good pids.

Also ive read that our diesels are around 40-60 to 1 at idle and crusing depending on tuning can be anywhere from 14:1 to 22:1

there are a lot of great articles in SAE and all over the net

 

[sweetdiesel]

Found a old spread sheet .....Dont know if it will even help you at all

 

[2500HeavyDuty]

you can rescale the maf, you can rescale the maf to where the truck will use a certian timing table under Amount of air of boost and use another for when the truck sucks in enough air to be racing.

or you can rescale it to better use the max injected fuel quantity table to control smoke.

 

[dmaxfireman]

Your hopelessly lost like the rest of us.
This place is a support group for addicts like us.:happy2:

support group!!??? more like enablers
:rofl::rofl:

 

[Fingers]

You should be able to use a calc PID with the sensor from greenlight

Ive read before that its not the greatest to use mm3 values instead try using Act boost/rpm

Fingers would be the good to talk to about this and IIRC he has allready made some good pids.

Also ive read that our diesels are around 40-60 to 1 at idle and crusing depending on tuning can be anywhere from 14:1 to 22:1

there are a lot of great articles in SAE and all over the net

I wrote a PID that uses pressure and duration to estimate the fuel being used compared to the air ingested. The scaling factor will need to be adjusted to your truck's injectors and tune. I set it to read 1:1 just as smoke comes out of the pipe.

Right now, it is limited by your MAF sensor's range. I have another, yet untested version that uses speed-density to estimate the air flow, but it is greatly affected by the engines volumetric efficiency. The MAF is more accurate and I am trying to learn enough to have the PID switch between the two methods when the MAF maxes out.

I'll post the MAF PID if anyone is interested.

 

[TheBac]

I would be interested, Jon. It would be a good start.

 

[Fingers]

The two lines of interest out of my calc_pids.txt file are:

#Equiv
*CLC-00-005
:1               0.0              1.5      .2   "({GM.MAINBPW}+{GM.PILOTBPW})*SQRT({GM.FRPACT})/({CALC.CYLAIR}*16115)"

and

CALC.Equiv                     F601 CLC-00-005   ":1"             Performance   "A/F ratio"

You will have to adjust the 16115 up or down to match your injectors. I prefer to have the result read 1:1 when the exhaust gas just goes from haze to black. With that as a base, I figure "best" to be somewhere around 0.80

It is not perfect, and does not track as well with large injectors, but at least it is consistent.

 

[JoshH]

Cool. Thanks for sharing.

 

[[email protected]]

Do you just paste that into the calc pids.txt file?