Emission dyno test shows HP too high?

[SSovaiko]

New to me 2008 6.7L 3500 DRW LB QC, 220k, 3.73, one owner, appears stock except for rear airbags. Took it in for the mandatory Colorado emissions dyno test after purchase and passed, but tester said the HP was significantly higher than stock for an 08. He claimed the 08 yields a reliable 255hp at the wheels at 60mph but mine was 282; it was also well above stock at the 40 (182hp) and 50 (239) mph test points. 60mph smoke opacity was just over normal values at 9%.
Based on the HP results the inspectors did a deeper visual inspection to verify nothing was altered or added under the hood or in the exhaust - nothing found.
My guess is the PO installed some type of ECM tune, or bumped up the injectors - Injectors I could examine if I pulled them out, or performed some type of flow test, but not sure how to verify the ECM is stock. And I thought the 6.7 could not be easily tuned without some sort of permanent external tuner - but this is my first 6.7, so I could be wrong.
Any suggestions for identifying the source of this nice HP bump - or is 282 not unusable for a stock 08?

 

[AH64ID]

What rpms/gears were those tests done at?

282 hp is a 20% drivetrain loss, which isn't out of the ordinary depending on the rpms/gear.

I'm actually surprised at that much opacity. The last emissions test I did on my 05 was 5% opacity without a DPF, but it was a tune I built for the emissions test.

 

[Tuesdak]

Did it pass?

 

[bcbender]

dang that's some strict testing... I guess I wont complain about ours.. I only have to do a safety check to make sure the lights and brake work....

 

[Signal73]

dang that's some strict testing... I guess I wont complain about ours.. I only have to do a safety check to make sure the lights and brake work....

Yea that’s what I was going to say!

 

[SSovaiko]

Did it pass?

Yes, no problem there. I just wondered if this HP result hints at some type of mod.

 

[SSovaiko]

What rpms/gears were those tests done at?

282 hp is a 20% drivetrain loss, which isn't out of the ordinary depending on the rpms/gear.

I'm actually surprised at that much opacity. The last emissions test I did on my 05 was 5% opacity without a DPF, but it was a tune I built for the emissions test.

 

[BarryG]

Colorado only tests for opacity. Those tests are only required in a few counties something like all of 5 counties and portions of a few more (they are all along the front range). The additional information was probably only for fyi purposes. I have had to get emissions testing done here for the last 20 years and I have never seen them look at the equipment, or even had them ask me questions about injectors, turbos, fueling devices, etc even though my 01 was modified fairly well. While I cant remember the cutoff year older ones have to be done yearly, newer ones every other year, new ones get a 4 year pass, though new gas vehicles get a 7 year pass. Not positive but I think turbo charged diesel engines threshold is 30% opacity. They do a snap test on the dyno, I know I cringe every time I have to go in.

 

[SSovaiko]

I might be chasing the wind on this 6.7. I just looked through 10yrs of emissions results on my 03 5.9 and the HP results at this same test center vary from 195 to 235, and 60 mph opacity from 2% to 23%, with nothing other than oil and filters changed on the truck. It is nice to see the trend, though, to ID any hidden issues.

 

[SSovaiko]

Colorado only tests for opacity. Those tests are only required in a few counties something like all of 5 counties and portions of a few more (they are all along the front range). The additional information was probably only for fyi purposes. I have had to get emissions testing done here for the last 20 years and I have never seen them look at the equipment, or even had them ask me questions about injectors, turbos, fueling devices, etc even though my 01 was modified fairly well. While I cant remember the cutoff year older ones have to be done yearly, newer ones every other year, new ones get a 4 year pass, though new gas vehicles get a 7 year pass. Not positive but I think turbo charged diesel engines threshold is 30% opacity. They do a snap test on the dyno, I know I cringe every time I have to go in.

Me too, they run that engine harder than I ever dare do! Almost sounds like a tractor pull at the flag drop. And yes, the HP results are just FYI, and not reported to anyone in the state.

 

[bigceltic]

Me too, they run that engine harder than I ever dare do! Almost sounds like a tractor pull at the flag drop. And yes, the HP results are just FYI, and not reported to anyone in the state.

I just set my Smarty on Half Power and always pass with flying colors! They have never commented on the very low HP numbers generated.

 

[Jim W]

I will stay in the land of IL. no emission testing on private diesel vehicles what's so, ever. No safety inspection either for 2500 trucks. They do a simple safety inspection on non-commercial 3500 and above trucks. Such as lights work, and brakes work with no bald tires on the truck, but that's it.

Now any gas engine vehicle must pass emission testing every 2 year's I think in 9 or 10 counties only. We haven't had any gas engine vehicles since 2010 until my wife got her new 2021 Santa Fe.