Forgive me if this has been talked about, I couldn't find any convos on it after searching.

Do OBDII scanners read hp and torque figures at the wheel or at the crank? It seems more likely that they are at the crank but if someone has any insight it'd be greatly appreciated.

Again, I apologize for the noob question here

 

FWIW it is not "read" - they are calculated based on factors it has collected, speed, time, distance etc

Unfortunately, it will likely be more "optimistic" than what it should be. You'd need a real baseline to know what to compare too.
For instance, a first gen "210" JCW kit, would put out about 184whp (+/- 5hp). If you were seeing 215 Hp - you'd know it isn't accurate in any way.

 

That's pretty much what I was thinking.

I compared bone stock to after JB+ install and the numbers did go up roughly 20hp/30tq, regardless of whether it was accurate to what the car is actually putting down or not. At least it's consistent I suppose.

 

It is as accurate as the figures you enter. Acceleration is super easy to calculate from the GPS, and power / force is just mass x acceleration.

If you accurately weigh your car and enter that into your scanner, you will get accurate power being produced. If you guess, you will get the same. If you do guess, any changes you make to the car will be correct in terms of percentage power increased / decreased. I.E: getting 10 hp more from opening your airbox / new header / whatever on a 100hp car (just an example for ease of math), is certainly a 10% raise even if your weight is wrong and the car actually has 90hp instead of 100.

James