So, I finally got around to getting my car dyno'd. My original concern was that my car was running rich. This was according to the Defi-D gauge I had installed. Whenever I went WOT, the needle would be pinned at 10. Like it was trying to go even further than that. However, when I got my car dyno'd, it showed it around 11.2-11.5. Now, I now that the O2 sensor is getting it's reading from pre-cat, and I know when they dyno'd, it was after the cat. I have a Helix HFC installed. My question is, will measuring after the cat make that much of a difference, or is the gauge messed up.

BTW, the off the shelf tune yielded 260 w/ my mods. Very impressive according to Mike from Gruppe-S for the level of mods that I have.

 

Looks like pretty good power for the mods you have on that dyno to me.

You wideband is probably right, hitting around 10 or so on the street but the tailpipe showing 11.1-11.2 on the dyno. It will read a little leaner after the cat then before. shouldn't be a whole point though but dynos are a little different than the street.

What was your wideband reading on the dyno?

The one thing to know is that AFR curve is stable which is good.

My car has been on that dyno alot and what I can tell you is that my car runs richer on the street than that dyno because of airflow etc. If I run 11.2 on that dyno, my wideband shows about 10.8/10.9 on the street.

 

That's a nice graph. Everything looks real good.

 

now you need some cams!

 

One thing I do notice after looking at your graph again is that the HP dips when the AFR goes leaner from 6300 to 6800.

You might have knocked there.

 

razorlab, I'm not sure what it was hitting when they had it on the dyno. I wasn't there during the actual runs to see the gauge.

As for the part where it goes lean, I checked the 2nd and 3rd runs and they both go lean in the same spot. Any suggestions on what to do to get that fixed? Thanks for the help in advance!

 

Have Works take a look at the tune?

 

While the reading does register a little leaner, I wouldn't call it lean

 

I agree, I stated it went leaner for the record.

It does seem to make HP and trq drop at that area though... So his car might not like that AFR.

 

I apologize. In no way was I inferring that it was lean to a point of where I should be seriously concerned. In fact, I'm quite happy w/ the off the shelf tune and the power that my car put down. I was just wondering if my gauge was screwed up, or there is really that much of a change in the AF before and after the cat.

In regards to the slightly leaner part, is it something I should have looked at in the future. Is there anything I can do myself to check to make sure I'm running at optimal performance? Or is it possible to have you take a look at it? I appreciate all the help and responses!

 

We've seen differences as high as .5 (give or take a little) before/after cat. It depends on the cat and how far downstream the sensor is placed. Based on what I see on your charts, you're still well withing the margin of safety and shouldn't be anything to be concerned with.

 

Jamie, that's what I figured. Now, I'll just waiting on your WI kit...