Engine Dyno vs Chassis Dyno Power Gains Differences?

[MrSony]

Say you get 35hp from an intake swap on an engine Dyno. Before engine removal your car made say, 300 wheel hp. Would your car with the new intake make 335hp at the wheels?

Would there still be that 35hp gain? Or would it be diminished the same as flywheel to wheel hp? Like the 15% or whatever it is.

I'm sure it's a lot more complicated than that.

What say you guys?

 

[500/600]

Very legitimate question. Since drivetrain loss is typically a percentage, then 35 x 0.85. Typically that factor increases, but it’s never a free lunch. At the point that the factor has increased enough the weak link breaks. You fix the weak link with a stronger part and then the facto

if drivetrain loss were ever discussed as simply HP, then 35hp x 1.00 against the baseline. But it never is.

the harder that mechanical systems are worked, the more resistance they have to the work being given to them. Building hydraulic pressure, creating friction, and 90 degree angles are all a PITA.

don’t get bogged down in it. 35 engine hp is either worth it to you or not. If I were a salesman I would always tout engine hp gains.

Steve

 

[MrSony]

Very legitimate question. Since drivetrain loss is typically a percentage, then 35 x 0.85. Typically that factor increases, but it’s never a free lunch. At the point that the factor has increased enough the weak link breaks. You fix the weak link with a stronger part and then the facto

if drivetrain loss were ever discussed as simply HP, then 35hp x 1.00 against the baseline. But it never is.

the harder that mechanical systems are worked, the more resistance they have to the work being given to them. Building hydraulic pressure, creating friction, and 90 degree angles are all a PITA.

don’t get bogged down in it. 35 engine hp is either worth it to you or not. If I were a salesman I would always tout engine hp gains.

Steve

the 35 number was just for the sake of argument. I was brainstorming potential imaginary engine masters episodes and one I thought of was dynoing an engine in a car, then an engine dyno, swapping a part on (intake came to mind as it's easy), seeing a power gain (35, random reasonable number), and seeing if that power gain will be replicated in full back on a chassis dyno. It's quite an undertaking even to type, let alone set up and film, so I thought I'd ask here. thanks for the input 😀

 

[500/600]

those guys seem to be able to pack it into a 30 minute video🤪

Richard Holdener is the only legitimate person to listen to in my opinion. He is doing a series called ’the other guys’ on YouTube now that I highly recommend. Don’t be surprised to see him do a 350 Buick at some point (or at least a 455). He flashed a 472 Cadillac up on the screen yesterday as well as a bunch of other weird stuff. Some don’t like his personality but I do. Very interesting guy. He dispels a lot of fear based myths that plague normal conversations.

 

[airboatgreg]

I used to a car dyno back in the day for driveability issues. First thing you had to do was hook a vacuum gauge up and drive at 40 MPH on a flat road. You would then drive the car on the dyno at 40 MPH and load it until you achieved the same vacuum. That was your base point. It was a pain but was good for looking at the scope and the infra-red exhaust to set up a carburetor. Something the most people ignore is that it is easy to give the engine fuel but much more difficult to give it the air properly mixed with the fuel. Think 14 times more air then fuel.

 

[Supercharged111]

I've heard that the percentage thing isn't 100 percent, that the driveline saps more of a predetermined amount of power that will increase as power does, but not to the extent that the percentage lost remains constant. Of course I have done ZERO research to validate this, just throwing it out there.