I know I saw it somewhere.

I'm getting my blower done by Apten, and will want to dyno afterwards to make sure I'm not too lean.

I'm trying to determine what the (general) difference is between measuring A/F before the cats, and at the end of the tailpipe. I thought I read it is about 1/2 point leaner (on the A/F gauge) at the end of the tail pipe because the cats clean things up. Is 11.7-11.8 the number at the end of the tailpipe?

Anybody know or hear anything on this?

 

anybody?

 

Usually it is off a half point either way. The best and most exact reading is going to be directly in the o2. The tailpipe sometimes dosent get warm enough for a correct reading. However if you do both tests on the same dyno before and after it wont matter as long as it reads safe 11-12.0

JimIII

 

I didn't do a "before" test.
Are most people going on the 11.0-12.0 at the tailpipe?

 

It all depends how big your ***** are
or your tuners

I just made 501/615 with this A/F

 

When the tuners are striving for 11.7-11.8, is that a tailpipe number, or before the cats?

 

Other than the Big Boys that are dynoing over and over and now have a permanant hook up for the A/F,
I got to believe most of us (prob 80 % or more) have numbers
based on A/F taken via the tail pipe.

IT'S NOT bad or anything, it's just like EVERYTHING in life,
there's always a better "or more accurate" way of doing it