A/F readout delay
 

On the racepak, how much delay from the RPM readout is the Air Fuel readout?

Re: A/F readout delay
 

Marty,
On my Holley system it seems to be .4 second.

Re: A/F readout delay
 

Thanks Bob! I was expecting something like that How did you determine that amount of delay?

Re: A/F readout delay
 

About .2 of a second on the racepak. I look at engine rpm and my shift point vs biggest fluctuation of O2.

Re: A/F readout delay
 

My delay is .2 second also. Each step on the graph is .5, not 1.0. I figured wrong.

Re: A/F readout delay
 

Thanks Bob Gullett and Bob Shaw! Good information!

Re: A/F readout delay
 

Marty, if your car is EFI, make a big change at like 6000 RPM, then see what RPM it shows up on your logger. I mostly look at high gear, since the A/F vs RPM error is going to be greater in lower gears due to the RPM increasing so much faster. And, I assume, if you leave off a 2 step, that your launch A/F looks much leaner due to the misfires caused by the 2step. Misfires put more oxygen in the exhaust, and our Wide Band O2 sensors calculate the air/fuel ratio by oxygen content.
I hope if you already knew all this, I didn't offend you. Maybe somebody did not know. Not trying to be a know-it-all.

Re: A/F readout delay
 

Just looked at my first run here at RT66 , my RacePak O2 is .021 behind RPM

Re: A/F readout delay
 

All good Ed, definitely not offended. I did know about the 2 step. I hadn't thought about altering fuel counts at a specific RPM to track the delay. That is a good idea. Thanks Ed!

Re: A/F readout delay
 

Thanks Tom! Quite interesting what you are seeing. Bob Shaw and Bob Gullett are seeing .2 seconds and you are seeing ,02 seconds. Do you have any logic about why you are seeing so much less delay?

Re: A/F readout delay
 

Marty , possibly because I'm reading 10" from the port as opposed to the collector.
I also have a brand new sensor installed for this race.
I looked at a few runs from last week and they were closer to .014 seconds ,so age can defiantly be a factor.



































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Re: A/F readout delay
 

Thanks Tom!

Re: A/F readout delay
 

So, Tom, your only looking at one cylinder?
You use a carburetor?

I am not sure why you would choose that, over the round part of the collector, past the transition section.

Re: A/F readout delay
 

If to close to end of collector it will give you a false reading at speed..........ask me how I know.

Re: A/F readout delay
 

At the end of the transition area being too close to the end of the collector = too short collectors. Right where the collector goes round would not be too close to the end on any headers I've ever seen. In the primary tubes only shows you that one cylinder. How darn short are your collectors? 10" or so from the end of the collectors will be OK going down the track WOT. Will show bogus Lean at idle & on the return road due to clean air being sucked back in during cam overlap cycles.

Re: A/F readout delay
 

After the diverge they are 4" , which is where the O2 is mounted.

Re: A/F readout delay
 

Ed , I run O2's in two of the primary's. I use the primary because when running on a throttle stop the reading in the collector will give a false lean reading .
When at WOT the primary and collector readings are fairly close. …..I run the collector O2 right at the leading edge of the merge.

Re: A/F readout delay
 

[QUOTE=Glenn Briglio;564343]After the diverge they are 4" , which is where the O2 is mounted.[/QUOTE

Automatic car? Might want to test some collector extensions.