A/F different at tail pipe vs. an O2 bung?
Thread Starter
Registered User
Joined: Sep 2002
Posts: 2,193
From: High Ridge, MO
A/F different at tail pipe vs. an O2 bung?
I was reading another thread, and this question caught my eye. Now, say I use my wideband setup, in an O2 bung, to get my a/f right around 12.8:1. Will the value be approximately the same if I take the car to a dyno and use a tailpipe wideband sensor? Also, I've always heard that LT1's run best around 12.6-12.8:1 a/f. Is that with a tailpipe sensor or one in an O2 bung?
Registered User
Joined: Nov 2004
Posts: 599
From: Waterloo, Ontario
Re: A/F different at tail pipe vs. an O2 bung?
With no catalytic converters, no exhaust leaks anywhere and the probe inserted far enough the readings should be equal. Both sensors would also need to be properly calibrated which is where most see the variance.
Thread Starter
Registered User
Joined: Sep 2002
Posts: 2,193
From: High Ridge, MO
Re: A/F different at tail pipe vs. an O2 bung?
My car has no cats. I'm just wanting to get an idea so that I can get a couple of tunes together and see which one does the best on the dyno. I didn't want there to be a huge variation with the a/f when I made my pulls. Thanks for the replies.
Registered User
Joined: Nov 2000
Posts: 1,937
From: Ft. Worth, TX
Re: A/F different at tail pipe vs. an O2 bung?
If no cats, then the reading should be the same.... but
Something I noticed with my GN and the narrow band O2 ( I have not had a chance to verify this with my WB 02 and my LT1)..
on the dyno, the O2 readings from the narrow band at WOT were always very lean...around 720-740mv (perfect for this car is 780mv).
Driving it home on that tune results in the O2s being a little fatter at 800mv which would have been my target anyway for the street....
So, I'm wondering if the same effect will be on the dyno for the LT1 since the "load" on the rear wheels is not the same on the dyno as it is actually propelling the car down the road... I'll find out in a few weeks when I go back to the dyno with the LT1 and my WB in hand....also see if my WB reads the same as the dyno WB.
Something I noticed with my GN and the narrow band O2 ( I have not had a chance to verify this with my WB 02 and my LT1)..
on the dyno, the O2 readings from the narrow band at WOT were always very lean...around 720-740mv (perfect for this car is 780mv).
Driving it home on that tune results in the O2s being a little fatter at 800mv which would have been my target anyway for the street....
So, I'm wondering if the same effect will be on the dyno for the LT1 since the "load" on the rear wheels is not the same on the dyno as it is actually propelling the car down the road... I'll find out in a few weeks when I go back to the dyno with the LT1 and my WB in hand....also see if my WB reads the same as the dyno WB.
Thread Starter
Registered User
Joined: Sep 2002
Posts: 2,193
From: High Ridge, MO
Re: A/F different at tail pipe vs. an O2 bung?
Originally Posted by 2QUIK6
I'll find out in a few weeks when I go back to the dyno with the LT1 and my WB in hand....also see if my WB reads the same as the dyno WB.
Last edited by Sweetred95ta; Sep 20, 2006 at 04:49 PM.
Registered User
Joined: Nov 2004
Posts: 599
From: Waterloo, Ontario
Re: A/F different at tail pipe vs. an O2 bung?
The dyno usually runs a little richer because it doesn't weigh as much as the car and no aerodrag. Although with my cutout open it allows the engine to make a little more power and my A/F was the same on the dyno as driving on the highway.
Thread
Thread Starter
Forum
Replies
Last Post
Henson071
Parts For Sale
8
Dec 30, 2015 09:55 PM
Devinfoote87
General 1967-2002 F-Body Tech
2
Jul 30, 2015 09:54 AM