Does a chassis dyno like a Dynojet use the A/F ratio info to determine hp/tq numbers, or is it strictly based off the power getting put to the rollers by the wheels? About a year ago I had my car dynoed and I put 278 at the wheels, but it also was severely leaning out with a 17:1 A/F. I've never had the car checked out, but it has always ran well since the dyno so I was thinking it was the shop's equipment.

 

If you have a cat and they stick the wideband in the tailpipe it could come out that lean.

 

I just recently ran on a Dynojet without the wideband O2 sensor. It measured that actual power put to the rollers.

 

dude your running dangerously lean just like me! get a maft and lt1 edit and adjust it back and regain that lost power! ishowed the same on the dyno!