Slant Six Forum
https://slantsix.org/forum/

A/F ratio
https://slantsix.org/forum/viewtopic.php?t=19085		 Page 2 of 2
Author:  LUCKY13 [ Thu Aug 10, 2006 8:15 pm ]
Post subject: 
IMHO you should just go ahead and buy a wide band kit if you really want it to help you tune. Yea I know it $350.00 but then you will be able to tune a/f just as the dyno guys do. I think I have seen some cheaper lately. I know you could get by for $200.00 if you used a DVOM to read the wideband setup & already had the meter.

http://www.dynotunenitrous.com/store/sc ... roduct=150


http://www.dynotunenitrous.com/store/sc ... roduct=169


http://www.dynotunenitrous.com/store/sc ... roduct=149


These are some of the best prices I have found, although I found one that was $200.00 that was claimed to be a good unit but cant find it at the moment.

I know you would rather find a cheaper way but unless you build your own controller & buy the sensor & then put a gauge on it I dont think you will find any cheaper, and then it will still cost doing it that way.

But to use a narrow band and gauge is about as good as snifing the exhaust and saying "OK thats rich".


Jess
Author:  Sam Powell [ Fri Aug 11, 2006 5:11 am ]
Post subject: 
That is a great link to DynoTune. Thanks. I have it bookmarked. About a year ago, while tuning the Mega Squirt, I bought a wide band kit for about $400 from a small company called lamdaboy. It worked pretty well for about a year, and right before I took the car off the road, it has been showing lean readings off the chart upon start up. It would lock up on 25:1. I know this is wrong, and assume maybe the sensor is fouled, or something. So apparently these devices are fairly sensative to fouling, or breakdown of somekind. The problem might be in the electronics as well.

Anyway, I vote with the crowd that favors a wide band gauge, but I do think the narrow band offers alot and is much better than just sniffing the tail pipe. I have both a narrow band, and a wide band gauge and could watch both simultaneously. There is some correlation between voltage and AF ratio on a narrow band,. My understanding is that the narrow band is not as precise as a wide band, but more important, the software in engine management systems is much more rudimentary in the narrow band.

The narrow band gets out of it's usefull range under WOT conditions. For the most part we will want something richer than 14.8:1 at WOT. Not only that the narrow band sensor is handled in a very digital way by the software to maintain 14.8 under normal engine operating conditions. If the voltage is over .5, then the ecm cuts back the pulse width, and if it is under .5 then it lengthenes the pulsewidth. The result is the engine is always bouncing back and forth rapidly between rich and lean by just a small amount. The wide band software, on the other hand gets more complex information, and adjusts the pulsewidth in a more sophisiticated way, plus it lets you target a specific AF ratio off of 14.8:1 for WOT tuning. When they dyno tune, the goal is not to hit a specific WOT AF ratio. They start with a good guess, do a dyno pull, compare the numbers on the AF ratio to HP readings, and then adjust the AF ratio for mximum HP.

Since this question is concerning tuning carburetors, I think a narrow band gauge can get you the info you need for most operating conditions except WOT which is going to be off of 14.8:1 by some amount. At that point you probably really do not care what the actual AF ratio is, the narrow band gauge will give you enough info to know if the flat spot you are experiencing is rich or lean, and then you will just tune for power and drivability, just like you always have done. You just will not have to take the risk of going the wrong way first, and making it worse, and then reversing direction. Plus an AF ratio gauge in the dash really looks cool. 8)
Author:  panic [ Fri Aug 11, 2006 5:34 am ]
Post subject: 
Vizard's method for using narrow band to tune WOT:
Tune to richest reliable reading on the gauge (for example 14.8).
Multiple main jet size by 14.8 / 12.5 = 118.4% of existing size
Install jets.
You have 12.5.
Duh.
Author:  Sam Powell [ Fri Aug 11, 2006 5:40 am ]
Post subject: 
Even if that formula works, only driving the car or dyno testing it will tell you if that AF ratio, or jet is the best size for your engine. Maybe 13.5 is better. Maybe 12.8 is better. It still takes work, even with the best tuning equipment, and AF gauges.
Sam
Author:  emsvitil [ Fri Aug 11, 2006 5:55 am ]
Post subject: 
Quote:
Vizard's method for using narrow band to tune WOT:
Tune to richest reliable reading on the gauge (for example 14.8).
Multiple main jet size by 14.8 / 12.5 = 118.4% of existing size
Install jets.
You have 12.5.
Duh.

You need to use the areas of the main jets............. (or flow rate)
Author:  panic [ Fri Aug 11, 2006 7:52 am ]
Post subject: 
Of course, what was I thinking?

I say something that is:
1. true
2. helpful
3. no one else has

and immediately the children must find fault with it.

Have fun, don't hurt yourself with those crayons.
Author:  vynn3 [ Fri Aug 11, 2006 9:25 am ]
Post subject: 
Quote:
Of course, what was I thinking?

I say something that is:
1. true
2. helpful
3. no one else has

and immediately the children must find fault with it.

Have fun, don't hurt yourself with those crayons.
Please, panic, feel free to find a forum where your opinions will be properly appreciated, and post there instead.

VM
Author:  LUCKY13 [ Fri Aug 11, 2006 9:59 am ]
Post subject: 
Yes the narrow band can be used & with some common sense & practis even use in some what acurate way. But if you buy a good gauge & a new sensor you will have close to $100.00 in it. If I can find that link to the new one that just came out at $200.00 this not much more & will help alot better. I agree on the WOT tuning & if you are going to the extra to get something to tune with I would think WOT would be a big part of your goals. But money & goals do play a lot on ones choices. I will fid the other setup today & get the link.

Sam I think you sensor has just died on you. Heat & over rich fuel is what usaully kills them, or getting antyfreeze or other cemical on them. Some say that Race fuel kills them also but I have seen them last in race fuel if all other things are right.

But the better you get your A/F it will pay off with power & economy & pay for itself in the long run.

Jess
Author:  LUCKY13 [ Fri Aug 11, 2006 10:29 am ]
Post subject: 
I did find this if you are good on building stuff like this. Then you would need the sensor(I think you can get sensor for $79.99)


http://www.redline.lt/magazine/spec-fea ... icle/17/1/
Author:  emsvitil [ Fri Aug 11, 2006 12:54 pm ]
Post subject: 
Quote:
Of course, what was I thinking?

I say something that is:
1. true
2. helpful
3. no one else has

and immediately the children must find fault with it.

Have fun, don't hurt yourself with those crayons.

I didn't fault it, but clarified it a little...............
Author:  JDS [ Fri Aug 11, 2006 1:35 pm ]
Post subject: 
i have seen the do it yourself one on a Soobie Sight, total cost was like $15. but i would honestly just buy a premaid unit. i do like the fact that it is very low-key. that is what i am looking for, something that is nearly hidden..
Author:  rebel_cat68 [ Tue Aug 15, 2006 8:36 am ]
Post subject:  A/F stuff from Australia
Found this address while searching thru a Finnish ricebucket-site.
They were discussing about the subject two years ago, but the aussie-site is still working.

http://www.wbo2.com/

Might be helpful.
Author:  rebel_cat68 [ Tue Aug 15, 2006 8:41 am ]
Post subject:  A/F stuff from Australia
Found this address while searching thru a Finnish ricebucket-site.
They were discussing about the subject two years ago, but the aussie-site is still working.

http://www.wbo2.com/

Might be helpful.
Author:  tophat [ Tue Aug 15, 2006 6:00 pm ]
Post subject: 
A tip to the cheep. O2 sensor "bungs" are like 9.99 at jeg$ or $ummit. Get some big ford (yeha I know) sparkplug nonfoulers, just cut to the size you want with a hacksaw.

interesting topic
tophat
Author:  emsvitil [ Tue Aug 15, 2006 7:05 pm ]
Post subject: 
Quote:
A tip to the cheep. O2 sensor "bungs" are like 9.99 at jeg$ or $ummit. Get some big ford (yeha I know) sparkplug nonfoulers, just cut to the size you want with a hacksaw.

interesting topic
tophat

Here's a cheap way...........

http://www.slantsix.org/forum/viewtopic.php?t=17845
Page 2 of 2 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/