Why do most people's dyno sheets not show the a/f ratio? Is that something extra that you have to ask for when you go to the dyno?

 

I just looked into getting mine done and there were two different prices. $65 for 4 pulls just the torque and HP and $85 if you want the A/F ratios. I am getting the a/f ratios. Just waiting to get a scheduled time.

 

this is very true indeed ? it cost me an additional $65.00 to have my A/F checked..

 

Wow, mine only cost $55.00, but that was a single pull. But it wasn't anything extra for a/f, but that's pretty much the only reason I got one.

 

actually you got a pretty good deal.. I got 2 runs with A/F for $85.00 plus I had to pay an additional $32.50 for the use of the wideband 02 sensor and $ 34.00 to have the 02 sensor bung welded, but again for just the 2 runs with A/F alone ? was $85.00.. be glad that you don't live in the northeast lol.

 

Why would you put a modern car on a dyno just to see the HP and Torque when air - fuel - spark is the determining factor in performance.

If your stating that the a/f's are not appearing on the graph thats just a simple matter of asking the dyno dude or dudess to include it in the snap shot.

 

Sorry, I got confused by that last statement, you do mean assuming they hooked up a wideband, right? They just can't give you your A/F by doing dyno pulls to check horse power. They have to hook up extra equipment that typically costs more to do.

If that's what you were implying, nevermind!

 

well no you can also check by tailpipe, I understand it is after the catalytic converter, but I believe there are calculations to get you in the neighborhood. Most dyno's have a tailpipe sensor or you can do the wideband as well. Have you ever gotten your car checked by the state emissions etc. They use a tailpipe sensor while running on a dyno to tell if you are running rich, lean , crappy in otherwords. Also they can tell how rich your running by pointing some sort of spectromoter at the general direction of your car on highway ramps to check what you are running and if you will pass emissions. Also I imagine the 02 sensor itself is telling the computer what a/f your running, so lots of info I am sure to get you close. good luck

 

The stock 02 sensor only has two conditions, lean or rich. Doesn't relay how lean or how rich, just lean or rich.

 

Exactly.

I haven't been to the dyno before so i didn't know if measuring the a/f was an extra service. That's why I asked. Also, do they stick a sensor into the end of the tailpipe, or do they plug a wideband sensor into one of the rear o2 bungs?

 

You dont need a wide band 02 sensor when doing dyno pulls. The dyno guys use whats call sniffers. This thing has a long pipe usually 1/4" to 3/8" thats stuffed up the tall pipe to take samples. Then through some magic it is converted to A/F on the dyno graph.

Now, hard core guys with beefed up engines will run a wide band taking the sample just before the cats. This is by far the most accurate way to monitor your A/F.

The new Live Wire that SCT is coming out with next year will require the installation of a wide band if you wish to see your A/Fs all the time. This is really good information along with monitoring the timing.

Putting a car on a dyno will not tell you how the car is going to perform on the streets or track. Dyno pulls will only let you know if your in the ball park.

The correct and most accurate way to tune your car is to datalog your runs down the track and after each run make adjustments to the a/f and timing as required to produce maximum hp and torque. This has to be repeated a number of times.

 

You need to move farther North East. Our guy does 3 pulls with A/F for $75.
http://www.performance-dyno.com/

 

In the meantime ? I found a new tuner who's quite a bit closer and more reasonable than the last guy who dyno tested my Stang www.powerhouse411.com