Dyno calibration

[RestoCreations]

Originally Posted by vector1

i think it would be difficult for someone selling engines, the fudge factor could be appetizing.

used to shoot trap and clubs although supposed to set all their targets to the same distance would fudge to keep the scores up, and the shooters knew where to go. some of that has probably been aleviated with the use of radar guns.

I dont know, there are a lot of people out there that are a bit clueless when it comes to engines and are desperate for a number to brag about. I was one of those people about a decade ago. I had a 327 SBC built by a local shop and they gave me a dyno sheet that said it put out 360hp at the rear wheels. This was a stock motor, with stock iron heads, 600cfm holley, stock crappy flowing aluminum intake, etc. I believed them and bragged to everyone about the motor until i was corrected by educating myself. Not to get further off topic, but my favorite dyno sessions to watch are the ones with stock sixties muscle cars. The owners tend to think that the factory flywheel hp ratings that were done 40 plus years ago with zero accessories attached and long tube headers installed are accurate. Then when their small block rated at almost 400hp from the factory puts out a 160-200 at the wheels they are scratching their heads.

[undy]

and another thing....


Most builders have optimal flowing headers, very free flowing air cleaner (or none at all) and zip point squat accessories when it's on the engine dyno. Now take that same engine, add the average Cobra side pipes, 1 7/8" tall air cleaner and the remaining accessories and your legit 600 hp engine now is 525 HP, engine builder's integrety still intact (somewhat).

The OEMs ( and a few such as Katech, etc) are really the only people who dyno an engine "as installed". This is not a zinger to the engine builders here as there's an infinate amont of installation variables that just can't be accouted for in every dyno instance. That's why a bone stock Z06 typically chassis dynos around 450 RWHP, providing a nominal 11.5% drivetrain power loos and the average "600" HP Cobra loses 20%+ on the chassis dyno.