AFR TUNING

[Sonny S.]

I've heard it said many times that 13.2:1 AFR @ WOT is the best AFR for maximum power.
IS THAT TRUE ?
If you go leaner and remove timing accordingly to eliminate pinging can you safely make more power at WOT ?
Do you have a target AFR other than 13.2 that you shoot for as a starting point for a WOT pull ?

Thanks,
Sonny

[FLTRI]

I've heard it said many times that 13.2:1 AFR @ WOT is the best AFR for maximum power.
IS THAT TRUE ? Yes, 13.2-13.5:1 for street applications is ideal.

If you go leaner and remove timing accordingly to eliminate pinging can you safely make more power at WOT? Leaning the AFR (from ideal) and retarding timing will reduce power.[/i]
Do you have a target AFR other than 13.2 that you shoot for as a starting point for a WOT pull ? No

Thanks,
Sonny

[Sonny S.]

Bob,

You must feel like the Lone Ranger. 68 people have viewed this but only you had an answer.

[Herko]

Bob,

You must feel like the Lone Ranger. 68 people have viewed this but only you had an answer.

Rest assured though, you got a good answer.
In my book, Bob's one of the guys in the Starrett category.

[PanHeadRed]

>only you had an answer<

Are you sure?

[Sonny S.]

>only you had an answer<

Are you sure?

Well Dwight,

I didn't see you adding any great words of wisdom..... got any ?
Tell us the FACTS about tuning and AFR.... not what you've read, what you've done, and the results.

[FLTRI]

 

[PanHeadRed]

Sonny, as I have stated many times I am not a tuner, and don't claim to be, I don't own or operate a Dyno, so who would possibly take me serious? Besides who would believe it unless it's posted on an internet forum any way.

I will have to admit I learn a lot from reading, I do read more then this site, and I am not ashamed of it.

As for words of wisdom?  I do have some.

1. "Experience only matters if you learn from it."
2."Not everything that counts can be counted, and not everything that can be counted counts"  -Albert Einstein


Oh, one more...."best power is 13.2"



Don't be hate'n.

[Sonny S.]

Sonny, as I have stated many times I am not a tuner, and don't claim to be, I don't own or operate a Dyno, so who would possibly take me serious? Besides who would believe it unless it's posted on an internet forum any way.

I will have to admit I learn a lot from reading, I do read more then this site, and I am not ashamed of it.

As for words of wisdom?  I do have some.

1. "Experience only matters if you learn from it."
2."Not everything that counts can be counted, and not everything that can be counted counts"  -Albert Einstein


Oh, one more...."best power is 13.2"  What happen to Einstein's quote # 2 ?



Don't be hate'n.

That was pretty smooth Dwight...you must be feeling better.
Oh, I get it, that was PHR talking.... gottcha 

3.  " A double minded man is unstable in all his ways "  - James 1:8

[PanHeadRed]

>Oh, I get it, that was PHR talking....,

Yeah, try and keep up would ya?

[mayor]

OK, let's look at this differently.  Tuners at what Air/Fuel ratio does torque typically drop (please provide lean and rich figures)?

[crazycalvin]

OK, let's look at this differently.  Tuners at what Air/Fuel ratio does torque typically drop (please provide lean and rich figures)?

Good way of putting it WannaB.  Later, Calvin.

[FLTRI]

Typically with these builds, power (HP/TQ) will be maximized between 12.8(for long term WOT to cool combustion temp)-13.5(short duration WOT street applications). Richer and leaner reduces power.

[whittlebeast]

Be very carfull comparing the AFR from one dyno to the next as the wide band AFR devices can get out of calibration from one to the next.  The wide bands are great for finding holes in the fuel map and knowing how deep the hole is but a little sketchy on the overall AFR.  They should at least be compared to a narrow band on occasion and have a free air calibration done on a regulat basis.

Most wide band readings are sketchy when exposed to large & quick changes in exhaust temp.

AW

[FLTRI]

"Be very carfull comparing the AFR from one dyno to the next as the wide band AFR devices can get out of calibration from one to the next".(you must be careful not to get cought up with wideband vs narrow band sensors as they are 2 completely different animals. A wide band sensor is by design much more accurate than a narrow band sensor for anything other than 14.7:1. This is because a narrow band sensor is nothing more than a rich/lean switch indicating richer or leaner than 14.7:1)   The wide bands are great for finding holes in the fuel map and knowing how deep the hole is but a little sketchy on the overall AFR. (Not sure where this came from but it is because of wideband sensors that we can tailor the AFR to whatever we desire. This cannot be done with a narrow band sensor.) They should at least be compared to a narrow band on occasion and have a free air calibration done on a regulat basis.

"Most wide band readings are sketchy when exposed to large & quick changes in exhaust temp." (Also, not sure where this came from as the most all racing engine builders (ie: NASCAR, IRL, etc) in racing utilyze wideband sensors to accurately measure O2 content. These engines see huge swings in exhaust temp especially in any type of motorcycle or automobile road racing.

Maybe someone else knows about these wideband sensors that will chime in on this,
Bob

[mayor]

Typically with these builds, power (HP/TQ) will be maximized between 12.8(for long term WOT to cool combustion temp)-13.5(short duration WOT street applications). Richer and leaner reduces power.

Bob, I'm not trying to paint you in a corner, but let me see if I am reading this right:
12.8 is primarily used due to the cooling affects of the richer mixture for race type long term exposure at WOT?
13.5 is good but is hot so long term constant afr's at this range is not recomended (occasional run-ups at WOT)?

[FLTRI]

Typically with these builds, power (HP/TQ) will be maximized between 12.8(for long term WOT to cool combustion temp)-13.5(short duration WOT street applications). Richer and leaner reduces power.

Bob, I'm not trying to paint you in a corner, but let me see if I am reading this right:
12.8 is primarily used due to the cooling affects of the richer mixture for race type long term exposure at WOT?
13.5 is good but is hot so long term constant afr's at this range is not recommended (occasional run-ups at WOT)?

Yes, you got it. Because racing engines spend most of their time under maximum loading as well as WOT, they will live longer and tolerate WOT for long periods because the additional fuel helps keep the combustion temps in a range where things won't start melting. Whereas a street engine hot-rodded occasionally doesn't need to have the combustion chamber additionally cooled @ WOT.
Bob

[mayor]

Bob, you are the man!

did you read that PBR- 

[whittlebeast]

See

http://www.newtiburon.com/forums/showthread.php?t=109436

The response time in changing exhaust flow and exhaust temp and the ability of the wideband heater to keep up is the issue.  I have good friends the design widbands for the OEs that first told me about the issues.  They have to program into the EFI logic, when to ignore the wideband.  Everything works fine in a racecar as the power and heat is high almost all of the time.

Narrow bands are extreamly accurate over a fairly wide temp range when at 14.7 +/- a very small range.  Either they smell o2 or they don't.

AW

[mtnmotorrider]

Let me take a swipe at this max power AFR thing as I understand it.  For maximun WOT power, a richer AFR of 12.5:1 to 13.1:1 is used primaryto provide enough fuel molecules to insure all of the oxygen molecules are attached to and burned, not the reverse as is popularly believed (D. William Denish, The V-Tuners Handbook, volume two).   In other words, you want to make sure all of your available air flow is fuel bearing, if that makes sense.  He goes on to say a peak power AFR for a normally aspirated engine will be roughly 13.1:1.  His words, not mine.  Of course this makes your gas mileage suck, so I run 13.5 for everything except 13.0 for WOT above 60% throttle and 14.5 for light throttle cruise range.