AFR

[IMINHELL]

Here is a good one for you guys. Would you say that an O2 sensor does a good job of measuring AFR? Most of us would probally answer "yes". The truth is that they do not always work as intended. I'd say 50% (at least) of the time using a WBO2 to tune a car is useless. I know, I know, that sounds really stupid, but . . . From the readings that sensor gave you what do you actually know? Answer: AFR. You don't actually know the things that will make you more power. Like the homoganity (sp?) of the mixture, tumble in the cylinder, actuall flame speed, ect. Even a "rich" mixture can damage an engine. Lets say you have a pocket of air/fuel in the chamber that is mixed so rich it won't ignite, when that pocket is expelled out the exhaust you now get a messed up AFR reading; You actually have uneven heating of the chamber and thus uneven loading on the piston/pin/bearing/rings.

There is nothing wrong with a lean burn - as long as the in-cylinder temps do not get too high (roughly 1600*F).


John

[umdivx]

Here is a good one for you guys. Would you say that an O2 sensor does a good job of measuring AFR? Most of us would probally answer "yes". The truth is that they do not always work as intended. I'd say 50% (at least) of the time using a WBO2 to tune a car is useless. I know, I know, that sounds really stupid, but . . . From the readings that sensor gave you what do you actually know? Answer: AFR. You don't actually know the things that will make you more power. Like the homoganity (sp?) of the mixture, tumble in the cylinder, actuall flame speed, ect. Even a "rich" mixture can damage an engine. Lets say you have a pocket of air/fuel in the chamber that is mixed so rich it won't ignite, when that pocket is expelled out the exhaust you now get a messed up AFR reading; You actually have uneven heating of the chamber and thus uneven loading on the piston/pin/bearing/rings.

There is nothing wrong with a lean burn - as long as the in-cylinder temps do not get too high (roughly 1600*F).


John

well depending on which WB sensor you go with will determin how acurate it is, like they say you get what you pay for. Most of the AEM WB kits I've seen are acurate, as i've seen them compaired side to side while on a dyno getting tuned.

Now the cheap AFR kits you can get that just piggy back onto your stock O2 sensor is just crap and won't tell you anything.

But I do get what your saying. Most of us here, well teh boosted ones will never have a condition where its mixed too rich, well maybe Trahma but even then I don't think I've seen a "over rich" condition like that, mostly in the big v8 beasts and such.

But in the end having a WB02 while major boosting, or hot rodding will be better than not knowing at all.

- Josh

[focinite]

ah yes but i see where inhell is coming from, the wb02 in not really telling you whats going on in the cylinder, it only gives a calculated read from whats left over after the burn. now a fuel sensor and a air sensor ( if they exsisted) in the cumbustion chamber reading before and after ignition would be ideal!!!!! but yes how would you know how acurate the 02 really is? but there is always the old sckool way of reading plugs, driving next to a wall to hear ping. plus on a dyno your AFR is not gonna be the same as on the street, a dyno is a pretty stable enviroment the street , on the other hand has a lot of veriables, like up hill , down hill, oh yeah , cool and warm pockets of air. im one that feels a AFR meter and a WBO2 are good tools to tune but not the main tools. a good laptop tune program is your best freind and a empty highway i know im babbaling but hey, if you dont know what yer talking about , bull shit it up reall good , so people think you know

[Louis Zerr]

3 words-Data logging. Know what you car is doing in more than one way. You can tell what voltages your MAF is at which correlates to air flow, you can tell what your duty cycle and voltage your injectors are which indicates how much fuel is dumping in and you know how much unburnt fuel is left via the WBO2. These are 3 great resources for tuning. (of course they are just eh beginning).

Too much fuel can cause puddling of the fuel on the top of the cylinter causing that fuel to detonate at temp which causes hot spots, pitting and ultimately piston failure.

[IMINHELL]

Well, I am pleased that this did not fall on deaf ears. The "real" tools are actually out there. It's just that shops do not want to pay for them because they do not believe the returns are worth the money.

It is actually possiable to "see" what is going on in the chamber for every cycle and tune from that point. Examples follow:

http://www.ucl.ac.uk/chemeng/research/c ... index.html

http://omni.cc.purdue.edu/~tlrobert/Spa ... tation.htm

http://www.bridgeanalyzers.com/

http://www.tfxengine.com/

(just a start of what I all have saved)


John

[sc0tty8]

The best way to make the most power is have your wastegate malfunction and your granny getter takes off like a mother fuck, then you spray the ass behind you with the oily james bond smoke screen

I seen the rain washed away my oil slick already

[focinite]

The best way to make the most power is have your wastegate malfunction and your granny getter takes off like a mother fuck, then you spray the ass behind you with the oily james bond smoke screen

I seen the rain washed away my oil slick already

man stop!! your making me cry imagen what that looked like from behind yer car