Last September I had my truck on a dyno and it made around 235 hp. In October I got a DennyT stage II pin and there was definitely a noticeable difference in the way the truck ran. I haven't noticed any problems since then. Yesterday I got to make another dyno run on a different dyno. To my surprise the truck only made 200 hp. I pulled the fuel pin out today to see if anything was wrong and the only thing I found was a bunch of rusty looking crud on the fuel pin but other than that it looked like it was working right. I cleaned it up and put some grease on it and put it back in and I can't say that I can tell any difference while driving. There is a few oil changes on the air filter and the fuel filter these are the only other things I can think of that would cause a problem. Is there anything else I should check.

 

Well...

What was the torque yesterday?

What was the temp in Oct compared to yesterday?

Auto or manual?

Same gear at both pulls?

Same dyno?

Same operator?

Same boost pressure?

See, there are a LOT of variables.

I would check to make sure the pin is coming out. Pull the DennyT, stick a very small screw driver (glasses type) down the back side of the whole (toward the driver, NOT the radiator), while hold the screw driver toward the back move the throttle lever.If the pin sticks out, you can easily push it back in if the screw driver is there. If it doesn't pop out, there is your problem.

Also, do you see a wear mark or any mark on the cone where the pin is riding?

 

Pin is coming out. Not the same dyno same operator though, same manual transmission. Don't know the rest. The second dyno couldn't measure torque on old junk.

 

Please post a pic of the dyno-sheet.



You mean he didn't have a working optical pick-up to read crankshaft rpms? > Shame on him.

 

Don't have the October dyno sheet but I will post the sheet from yesterday.

 

The dyno sheet is the last photo in this album.
https://www.facebook.com/media/set/?...5&l=1eff995a58

 

The dyno is no set thing. 10 different dyno's will show 10 different numbers. Even the same dyno can be off calibration from one time to another. Also the operator can change input as well.

 

What's really disappointing with that sheet is the dyno operator doesn't have it set to show engine rpm, or mph. It shows "Time" . . . . . . ?

I agree with Richie about not putting a lot of faith in a dyno run, but I personally wouldn't bother going back to that place.

 

That seems to be the general consensus among my friends that were there running their trucks. My wife did win a Diamond Eye exhaust system. So it was a good day over all.

 

Best dyno IMO is 1/4 mile MPG vs. vehicle weight. Much closer to actual WHP than different dyno's. If its a reputable diesel shop dyno like Relentless Diesel, then I'd say the numbers will be close. But shops used to ricers and gasser rides won't know as much about dynoing a diesel truck. My dyno had a big difference from 4th gear to 5th gear runs due to engine load.