HP = (TQ x RPM) / 5252
TQ = (HP x 5252) / RPM
If TQ = 428 @ 4869, then HP = (428 x 4869) / 5252 = 397
TQ = (397 x 5252) / 4869 = 428
But wait, that’s what the Accessport shows?!?! That’s because that little device is calculating the numbers exactly how they should be and giving the RPMs where their calculations would be correct. Therefore, it’s all a ‘guess’ really. If you throw the car on a dyno, the numbers, specifically RPM will be drastically diffferent.
In a real world situation, both can not be peaking at the same RPM. They always cross (read: match) at 5,252 RPM.
I’d show a mock dyno chart to show you how it’d look, but since I’m working and don’t really know how to do so, it’s a bit impossible.